Matt Walker: Sleep | Lex Fridman Podcast #210
the following is a conversation with matt walker sleep scientist professor of neuroscience and psychology at berkeley author of why we sleep and the host of a new podcast called the matt walker podcast it's 10 minute episodes a couple of times a month covering sleep and other health and science topics i love it and recommend it highly it's up there with the greats like the hubermann lab podcast with andrew huberman and i think david sinclair is putting out an audio series soon too i can't wait to listen to it i'm really excited by the future of science in the podcasting world to support this podcast please check out our sponsors stamps.com squarespace athletic greens better help and on it their links are in the description as a side note let me say that to me a healthy life is one in which you fall in love with the world around you with ideas with people with small goals and big goals no matter how difficult with dreams you hold on to and chase for years life should be lived fully that to me is the priority that to me is a healthy life second to that is the understanding and the utilization of the best available science on diet exercise supplements sleep and other lifestyle choices to me science in the realm of health is a guide for we should try not the absolute truth of how to live life the goal is to learn to listen to your body and figure out what works best for you all that said a good night's sleep can be a great tool in making life awesome and productive and matt is a great advocate of the how and the why of sleep we agree on some things and disagree on others but he's a great human being a great scientist and as of recently a friend with whom i enjoy having these wide ranging conversations this is the lex friedman podcast and here is my conversation with matt walker you should try these shades on and see what you look like so they are now your shades and that's not the question it's the same thing as uh putin took the super bowl ring and it's now his ring [Laughter] yeah one wonders if he was offered it but um they are yours [Laughter] when did you first fall in love with the dream of understanding sleep like where did the fascination with sleep begin so back in the united kingdom you can sort of start doing medicine at age 18 and it's a five-year program and i was at the queen's medical center in the uk and i remember just being fascinated by states of consciousness and particularly anesthesia i was thinking isn't that within seconds i can take a perfectly conscious human being and i can remove all existence of the mentality and their awareness within seconds and that stunned me so i started to get really interested in conscious states i even started to read a lot about hypnosis and all of these things hypnosis even sleep and dreams at the time they were very esoteric it was sort of charlatan science at that stage and i think almost all of my colleagues and i are accidental sleep researchers you know no one as i recall in the classroom when you're sort of five years old and the teacher says what would you like to be when you grow up you know no one's putting their hand up and saying i would love to be a sleep researcher and so when i was doing my phd i was trying to identify different forms of dementia very early on in the course and i was using electrical brainwave recordings to do that and i was failing miserably it was a disaster just no result after no result and i used to go home to the doctor's residence with this sort of little igloo of journals that at the weekend i would sort of sit in and uh and read and which i'm now thinking do i really want to admit this because it sounds like i had no social life which i didn't i'm a social leper but and i started to realize that some parts of the brain were um sleep-related areas and some dementias were eating away those sleep-related areas other dementias would leave them untouched and i thought well i'm doing this all wrong i'm measuring my patients while they're awake instead i should be measuring them while they're asleep started doing that got some amazing results and then i wanted to ask the question is that sleep disruption that my patients are experiencing as they go into dementia maybe it's not a symptom of the dementia i wonder if it's a cause of the dementia and at that point which was kafka 20 years ago um no one could answer a very simple fundamental question why do we sleep and i at the time didn't realize that some of the most brilliant minds in scientific history had tried to answer that question and failed and at that point i just thought well i'm going to go and do a couple of years of sleep research and i'll figure out why we sleep and then i'll come back to my patients in this question of dementia and as i said that was 20 years ago and what i realized is that hard questions occur very little about who asks them they will meter out their lessons of difficulty all the same and i was schooled in the difficulty of the question why do we sleep but in truth 20 years later we've had to upend the question rather than saying why do we sleep and by the way the answer then was that we sleep to cure sleepiness which is like saying all right you know we eat to cure hunger yeah that tells you nothing about the physiological benefits of food same with sleep now we've actually have to ask the question is there any physiological system in the body or any major operation of the mind that isn't wonderfully enhanced when we get sleep or demonstrably impaired when we don't get enough and so far for the most part the answer seems to be now so far the answer seems to be no so why why does the body and the mind crave sleep then why do we sleep how you know can we begin to answer that question then so i think one of the ways that i think about this or one of the answers that came to me is the following the reason that we implode so quickly and so thoroughly with insufficient sleep is because human beings seem to be one of the few species that will deliberately deprive themselves of sleep for no apparent good reason biological and what that led me then to was the following mother nature as a consequence so no other species does what we do in that context there are a few species that do undergo sleep deprivation but for very obvious clear biological reasons one is when they're in a condition of severe starvation the second is when they're caring for their newborn so for example killer whales will often deprive themselves the female will go away from the pod give birth and then bring the calf back and during that time the mother will undergo sleep deprivation and then the the third one is during migration when birds are flying trans oceanographic to 3 000 miles but for the most part it's never seen in the animal kingdom which brings me back to the point therefore mother nature in the course of evolution has never had to face the challenge of this thing called sleep deprivation and therefore she has never created a safety net in place to circumnavigate this common influence and there's a good example where we have which is called the adipose cell the fat cell because during our evolutionary past we had famine and we had feast and mother nature came up with a very clever recipe which is how can i store caloric credit so that i can spend it when i go into debt and the fat cell was born brilliant idea where is the fat cell for sleep where is that sort of banking chip for sleeping unfortunately we don't seem to have one because she's never had to face that challenge so even if there's not some kind of physics fundamental need for sleep that uh physiologically or psychologically the the fact is most organisms are built such that they need it and then mother nature never built an extra mechanism for sleep deprivation so it's interesting that why we sleep by not have a good answer but we need to sleep to be healthy is nevertheless true yeah and we have many answers right now in some ways the question of why we sleep was the wrong question too it's you know what are the pluripotent many reasons we sleep we don't just sleep for one reason because from an evolutionary perspective it is the most idiotic thing that you could imagine yeah you know when you're sleeping you're not finding a mate you're not reproducing you're not caring for your young you're not foraging for food and worse still you're vulnerable to predation so on any one of those grounds especially as a collective sleep should have been strongly selected against in the course of evolution but in every species that we've studied carefully to date sleep is present yeah so it is important so like you're right i think i've heard arguments from an evolutionary biology perspective that sleep is actually advantageous you know maybe like some kind of predator predator-prey relationships yeah but you're saying it actually makes way more sense what you're saying is it should have been selected against like why close your eyes yeah why because and you know there was an energy conservation hypothesis for a while which is that we need to essentially go into low battery mode you know power down because it's unsustainable but in fact that actually has been blasted out the water because sleep is an incredibly active process in fact the difference between you just lying on the couch but remaining conscious versus you lying on the couch and falling asleep it's only a savings of about 140 150 calories in other words you know you just go out and club another baby seal or whatever it was and you wouldn't worry you know so it has to be much more to it than energy conservation much more to it than sharing you know ecosystem space and time much more to it than simply predator prey relationships if sleep really did and you know looking back even very old evolutionary organisms like earthworms millions of years old they have periods where they're active in periods where they're passively asleep it's called lethargics and so what that in some way suggested to me was sleep evolved with life itself on it this planet and then it has fought its way through heroically every step along the evolutionary pathway which then leads to the sort of famous um sleep statement from a researcher that if sleep doesn't serve an absolutely vital function or functions then it's the biggest mistake the evolutionary process has ever ever made and we've now realized mother nature didn't make a spectacular blender with sleep you've mentioned the idea of conscious states do you think of sleep as a fundamentally different conscious state than awake awakenness and how many conscious states are there so when you're intuit your understanding of what the mind can do do you think awake state sleep state or is there some kind of continuum there's a complicated state transition diagram like how do you think about this whole space i think about it as a state space diagram and i think it's probably more of a continuum than we have believed it to be or suggested it to be so we used to think absent of anesthesia that there were really three main main states of consciousness there was being awake being in non-rapid eye movement sleep or non-dream sleep and then being in rapid eye movement sleep or dream sleep and those were the three states within which your brain could percolate and be conscious i you know conscious during non-rem sleep is maybe a stretch to say but i still believe there is plenty of consciousness there i don't believe that though anymore and the reason is because we can have daydreams and we are in a very different wakeful state in those day dreams than we are when we are as we are now together present and extraceptively focused rather than intraceptively focused and then we also know that as you are sort of progressing into those different stages of sleep during non-rem sleep you can also still dream depends on your definition of dreaming but we seem to have some degree of dreaming in almost all stages of sleep we've also then found that when you are sleep deprived there even individual brain cells will fall asleep despite the animal being you know behaviorally from best we can tell awake individual brain cells and clusters of brain cells will go into a sleep-like state and humans do this too when we are sleep deprived we have what are called micro sleeps where the eyelid will partially close and the brain essentially falls lapses into a state of sleep but behaviorally you seem to be awake and the danger here is road traffic accidents so these are the what we call these sort of micro sleep events at the wheel now if you're traveling at 65 miles an hour in a two ton vehicle you know it takes probably around one second to drift from one lane to the next and it takes two seconds to go completely off the road so if you have one of these micro sleeps at the wheel you know it could be the last microsleep that you ever have but i don't now see it as a set of you know very binary distinct you know step function state it's not a one or a zero i see it more of a as a continuum yeah so i've for for uh five six years at mit really focused on this human side of driving question and one of the big concerns is the micro sleeps drowsiness these kinds of ideas and one of the open questions was is it possible through computer vision to detect or any kind of sensors the nice thing about computer vision is you don't have to have direct contact to the person is it possible to detect increases in uh drowsiness is it possible to detect these kind of micro sleeps or actually just sleep in general um among other things like distraction these are all words that have so many meanings and so many debates like like attention is a whole nother one just because you're looking something doesn't mean you're loading in the information just because you're looking away doesn't mean your peripheral vision can't pick up the important information there's so many complicated vision science things there um so i i wonder if you could say something to uh you know they say the eyes or the windows to the soul do you think um the eyes can reveal something about uh sleepiness uh through uh through computer vision through just looking at the video of the face and andrew huberman and i your friend have talked about this so we'd love to work on this uh together so you should do it it's a fascinating problem but drowsiness is a tricky one so there's what kind of information there's uh blinking and there's eye movement and those are the ones that can be picked uh up with computer vision do you think those are signals that could be used to say something about where we are in this continuum yeah i do and i think there are a number of other features too i think um you know aperture of i so in other words partial closures foreclosures duration of those closures duration of those partial closures of the eyelid um i think there may be some information in the pupil as well because as we're transitioning between those states change there are changes in what's called the automatic nervous system or technically it's called the autonomic nervous system part of which will control your pupillary size so i actually think that there is probably a wealth of information when you combine that probably with aspects of steering angle steering maneuver and if you can sense the pressure on the pedals as well my guess is that there is some combinatorial feature that creates a phenotype of you are starting to fall asleep and as the autonomous controls develop the it's time for them to kick in some manufacturers auto manufacturers sort of have something beta version maybe an alpha version of of this already starting to come online where they have a little camera in the wheel that i think tries to look at some features almost everybody doing this and it's very alpha so uh you know the thing that you currently have some people have that in their car there's a coffee cup or something that comes up that you might be sleepy the the primary signal that they're comfortable using is the steering wheel reversals so so basically using your interaction with the steering wheel and how much you're interacting with it as a sign of sleepiness so if you have to constantly correct the car yeah that's a sign of like you starting to drift into micro sleep i think that's a very very crude signal it's probably a powerful one there's a whole other component to this which is it seems like it's so driver and subject-dependent the how our behavior changes as we get sleepy and drowsy seems to be different in complicated fascinating ways where you can't just use one signal it's kind of like what you're saying there has to be a lot of different signals that you should then be able to combine the hope is there's uh the searches for like universal signals that are pretty damn good for like ninety percent of people but i don't think we need to take necessarily quite that approach i think what we could do in some clever fashion is using the individual so what you and i are perhaps suggesting here is that there is an array of features that we know provide information that is sensitive to whether or not you're falling asleep at the wheel some of those let's say that there are ten of them you know for me seven of them are the cardinal features for you however you know six of them and they're not all the same sort of overlapping are those for you i think what we need is algorithms that can firstly understand when you are well slept so let's say that people have sleep trackers at night and then your car integrates that information that'd be amazing understands when you are well slept yeah and then you've got the data of the individual behavior unique to that individual snowflake like when they are well slept this is the signature of well-rested driving then you can look at deviations from that and patent match it with the sleep history of that individual and then i don't need to find the sort of you know the one-size-fits-all approach for 99 of the people i can create a very bespoke tailor-like set of features the savile row suit of sleepiness features you know that would be my if you want to ask me about moonshots and crazy ideas that's where i go but to start with i think your approaches is a great one let's find something that covers 99 of the people because the worrying thing about microsleeps of course unlike you know drugs or alcohol which you know certainly is a terrible thing to be behind the wheel with those often you you react too late and that's the reason you get into an accident when you fall asleep behind the wheel you don't react at all the you know at that point there is a two-ton missile driving down the street and no one's in control that's why those accidents can often be more dangerous yeah and the fascinating thing is in the case of semi-autonomous vehicles like tesla autopilot this is where i've had disagreements with mr elon musk is uh and uh the human factors community which is this community that one of the big things they study is uh human supervision over automation so you have like pilots you know supervising an airplane that's mostly flying autonomously the question is when we're actually doing the driving how do micro sleeps or general how does drowsiness progress and how does it affect our driving that question becomes more fascinating more complicated when your task is not driving but supervising the driving so your task is to take over when stuff goes wrong and that is complicated but the basic conclusions from many decades is that humans are really crappy at supervising because they get they get drowsy and lose vigilance much much faster the really surprising thing with tesla autopilot it was surprising to me it's surprising to uh the human factors community and in fact they still argue with me about it is uh it seems that humans in tesla's with autopilot and other similar systems are not becoming less vigilant at least the with with the studies we've done so there's something about the urgency of driving i can't i'm not sure the why but there's something about the risk i think the fact that you might die is still keeping people awake the question is as tesla autopilot or similar systems get better and better and better how does that affect increasing drowsiness and that's when you need to have that's what the big disagreement was you need to have driver sensing meaning driver facing camera that tracks some kind of information about the face that can tell you uh drowsiness so you can tell the car if you're drowsy so that the car can be like you should be probably driving or pull to the side right or i need to do some of the heavy lifting here yeah um so there needs to be that dance of inter interaction of a human and machine but currently it's mostly uh steering wheel based so you know this this idea that your hands should be on the on the steering wheel that's uh a sign that you're paying attention is um isn't outdated and a very crude metric i agree yeah i think there are far more sophisticated ways that we can solve that problem uh if we invest big philosophical question before we get into fun details um on the topic of conscious states how fundamental do you think is consciousness to the human mind i ask this from almost like a robotics perspective so in your study of sleep do you think the the hard question of consciousness that it feels like something to be us is that like a nice little feature like a like a like a quark of our mind or is it somehow fundamental because sleep feels like we take we take a step out of that consciousness a little bit so from all your study of sleep do you think consciousness is like deeply part of who we are or is it just a nice trick i think it's a deeply embedded feature that i can imagine has a whole panoply of biological benefits but to your point about sleep what is interesting if you do a lot of dream research and we've done some it's very very rare at all in fact for you to end up becoming someone other than who you are in your dreams now you can have third-person perspective dreams where you can see yourself in the dream as if you're sort of you know you've risen above your your physical being but for the most part it's very rare that we lose our sense of conscious self and maybe i'm sort of doing a sleight of hand because it's really what i'm saying it's very rare that we lose our sense of who we are in dreams we never do now that's not to suggest that dreams aren't utterly bizarre and i mean you know when you slept last night which i know um may have been perhaps a little less than than me but when you went into dreaming you know you became flagrantly psychotic and there are five essentially good reasons firstly you started to see things which were not there so you were hallucinating second you believe things that couldn't possibly be true so you were delusional third you became confused about time and place and person so you're suffering from what we would call disorientation fourth you have wildly fluctuating emotions something that um psychiatrists will call being affectively labile and then how wonderful you woke up this morning and you forgot most if not all of that dream experience so you're suffering from amnesia if you had to experience any one of those five things while you're awake you would probably be seeking psychological help but what so i placed that as a backdrop against your astute question because despite all of that psychosis there is still a present self nested at the heart of it meaning that i think it's very difficult for us to abandon our conscious sense of self and if it's that hard you know the old adage in some ways that you can't outrun your shadow but here it's more of a philosophical question which is about the conscious mind and what the state of consciousness actually means in a human being so i think that that to me you can you become so dislocated from so many other rational ways of waking consciousness but one thing that won't go away that won't get perturbed or sort of you know manicled is this your sense of conscious self yeah that's a strong sign that consciousness is fundamental to the human mind um or we're just creatures of habit we've gotten used to having consciousness maybe it just takes a lot of uh either chemical substances or a lot of like mental work to escape that i mean it's like trying to launch a rocket you know the energy that has to be put in to create escape velocity from the gravitational pull of this thing called planet earth is immense yeah well the same thing is true for for us to abandon our sense of conscious self the amount of biological the amount of substances the amount of wacky stuff that you have to do to truly get escaped velocity from your conscious self what does that tell us about then the fundamental state of our conscious self yeah it also probably says that that it's quite useful to have consciousness for uh for survival and for just operation in this world and perhaps for intelligence i'm one of the on the ai side people that think that uh intelligence requires consciousness so like high levels of general intelligence requires consciousness most people in the ai field think like consciousness and intelligence are fundamentally different you can build a computer that's super intelligent it doesn't have to be conscious i think that if you define super intelligence by being good at chess yes but if you define super intelligence as being able to operate in this living world of humans and be able to perform all kinds of different tasks consciousness it seems to be somehow fundamental to uh like to to to richly integrate yourself into the human experience into society it feels like you have to be a conscious being but then we don't even know what consciousness is and we certainly don't know how to engineer it in our machines i love the fact that there are still questions that are so embryonic because you know i suspect it's the same with you answers to me are simply ways to get to more questions you know it's questions where you know questions turn me on answers less so and i love the fact that we are still embryonic in our sense of arguing about even what the definition of consciousness is but i also find it fascinating i i think it's thoroughly delightful to absorb yourself in the thought think about the brain and we can move back across the complexity of phylogeny from you know humans to mammals to sort of birds to reptiles amphibians fish and you can bacteria whatever you want and you can go through this and say okay where is the hard line of you know what we would define as consciousness and and i'm sure it's got something to do with the complexity of the neural system of that i'm fairly certain but to me it's always been fascinating so what is it then you know is it that i just keep adding neurons to a petri dish and i just keep adding them and adding them and adding them at some point when i hit a critical mass of interconnected neurons that is the mass of the you know the interconnected human brain then bingo all of a sudden it kicks into gear and we have consciousness like a phase shift phase transition of some kind correct yeah but there is something about the complexity of the nervous system that i think is fundamental to consciousness and the reason i bring that up is because when we're trying to then think about creating it in an artificial way does that inform us as to the complexity that we should be looking at in terms of development i also think that it's a missed opportunity in the sort of digital space for us to try to recreate human consciousness we've already got human consciousness what if we were to think about creating some other form of why do we have to think that the ultimate in the creation of you know an artificial intelligence is the replication you know of a human state of consciousness can we not think outside of our own consciousness and believe that there is something even more incredible or more complementary more orthogonal [Music] so i'm sometimes perplexed that people are trying to mimic human consciousness rather than think about creating something that's different yeah i think of human consciousness or consciousness in general is this magic um superpower that allows us to deeply experience the world and just as you're saying i don't think that superpower has to take the exact flavor as humans have that's my love for robots i would love to add the ability to robots that can experience the world and other humans uh deeply i'm humbled by the fact that that idea does not necessarily need to look anything like how humans experience the world but there's a dance of um human to robot connection the same way human to dog a human to cat connection that there's a there's a there's a magic there to that interaction and i'm not sure how to create that magic but it's a worthy effort i also love just exactly as you said on the question of consciousness or engineering consciousness the fun thing about this problem is it seems obvious to me that a hundred years from now no matter what we do today uh people if we're still here will laugh at how silly our notions were so like it's almost impossible for me to imagine that we will truly solve this problem fully in my lifetime and and more than that everything we'll do will be silly 100 years from now but it's still a war that makes it fun to me because it's like you have the full freedom to not even be right just to try just to try as freedom and uh and i that's how i see that t-shirt please i love that so i and you know the human robot interaction is fascinating because it's like it's like watching dancing i've been uh dancing tango recently and just it's like there is no goal the goal is to create something magical and uh whether consciousness or emotion or elegance of movement all of those things uh aid in the creation of the magic and it's a free it's an art form to explore how how to make that um how to create that in a way that's compelling yeah i love that the line in sense of a woman with al pacino where he's speaking about the tango and he said really it's just freedom that if you get tangled up you just keep tangoing on i still to this day i think uh well first the second time i talked to joe rogan on his podcast i said we got into this heated argument about whether a sensible woman is a better movie than john wick because it's one of my favorite movies for many reasons one is for sensible women some scent of a woman uh partially know that by the way it's just you just yeah i don't know if you would actually know of awesome awesome yeah yeah i said i love the tango scene i love al pacino's performance it's a wonderful movie then joe joe was saying john wick is better so we to this day argue about this i think it depends in on what conscious state you're in yes that you would be ready and receptive to but um sense of woman i think it has one of the best monologues at the end of the movie that has ever been written or at least performed when al pacino defends the the younger yeah i uh i often think about that there's been times in my life i don't know about you where i wish i had an al pacino in my life where um integrity is really important in this life it is and sometimes you find yourself in places where there's pressure to sacrifice that integrity and you want uh what is it lieutenant colonel or whatever he was coming yeah come in uh on your side and scream at everyone and say what the hell are we doing here being you know unfortunately british and sort of having that slightly um awkward sort of huge grand gene it's it's very very at the opposite end of the spectrum of the remarkable feat of uh al pacino at the end of that scene but um and yeah integrity is um it's a challenging thing and i value it much and i think um it can take 20 years to build a reputation in two minutes to lose it and there is nothing more that i value than but integrity and you know if i'm ever wrong about anything i truly don't want to be wrong for any longer than i have to be um you know that's what being in some ways a scientist is you're you're just driven by truth and the irony relative to something like mathematics is that in science you never find truth what all you do in science is you discount the things that are likely to be untrue leaving only the possibility of what could be true yeah but in math you know when you create you know a proof it's a proof for you know from that point forward there is truth in mathematics and there's i think there's a beauty in that but i kind of like the messiness of of science because again to me it's less about the truth of the answer and it is more about the pursuit of questions but their integrity becomes more and more important and it becomes more difficult there's a lot of pressures just like in the rest of the world but there's a lot of pressures on a scientist one is like funding sources yeah i've noticed this that um you know money affects everyone's mind i think i've been always somebody that i believe money can't you can't buy my opinion uh i don't care how much money billions or trillions the but that pressure is there and you have to be very cognizant of it and make sure that your opinion is not defined by the funding sources and then the other is just your own success of uh you know for a couple of decades publishing an idea um and then realizing at some point that that idea was wrong all along right and that that's a tough thing for people to do but that's also integrity is to walk away is to say that you were wrong um that doesn't have to be in some big dramatic way it could be in a bunch of tiny ways along the way right like uh reconfigure your intuition about a particular uh problem that's and all of that is integrity when everybody in the room uh you know believes a certain thing everybody in the community believes a certain thing to uh to be able to still be open-minded in the face of that yeah and i think it comes down in some ways to the issue of ego that you bond your you know correctness or your rightness your scientific theory with your sense of ego you know i've never found it that difficult to let go of theories in the face of counter evidence in part because i have such low self-esteem well i i kind of like that i always like that combination i have the same i'm like very self-critical imposter syndrome all those things uh putting yourself below the podium but at the same time having the ego that drives the ambition to work your ass off like some kind of weird drive maybe like to drive to be better like thinking yourself is not that great and always driving to be better and at the same time because that's that can be paralyzing and exhausting and so on at the same time just being grateful to be alive but in the sciences in the actual effort never be satisfied never think of yourself highly that seems to be a nice combination i very much hope that that is part of who i am and i remain very quietly motivated and driven and i like you love the idea of perfection and i know i will never achieve it but i will never stop trying to so similar to you which sounds weird because there's all these videos of uh of me on the internet so i think i think i just naturally lean into the things i'm afraid of and i'm uncomfortable doing yeah like i'm very afraid of talking to people and you know just even before talking to you today just a lot of anxiety anxiety and all those kinds of things about talking to me yeah yeah oh nervousness uh fear in some cases uh self-doubt and all those kinds of things but i do it anyway so the reason i bring that up is um you've uh launched a podcast i have allow me to say i think you're a great science communicator so this challenge of being afraid or cautious of being in the public eye and yet having a longing to communicate some of the things you're excited about in the space of sleep and beyond what's your vision with this project i think firstly to your to that question like you i am always more afraid of not trying than trying yeah that to me frightens me more but with the podcast i think really i have two very simple goals i want to try and democratize the science of sleep and in doing so my goal would be to try and reunite humanity with the sleep that it is so desperately bereft of and if i can do that through a number of different means um the podcast is a little bit different than this format it's are going to be short form monologues from yours truly uh that will last usually less than just 10 minutes and i see it as simply a little slice of sleep goodness that can accompany your waking day it's hard to know what is the right way to do science communication like uh your friend mine andrew huberman is does he he's an incredible human being okay so he does like two hours of i wonder how many takes he does i don't know but it looks like he doesn't do anything he's that magnificent of a human being when i talk to him in like in person he always generates intelligent words well cited non-stop for hours so i don't he's a gatling gun of information and it's pristine and passion and all those kinds of things so that's an interesting medium i i wouldn't have um it's funny because i wouldn't have done it the way he's doing it i wouldn't advise him to do it the way he's doing it because i thought there's no way you could do what you're doing because it's a lot of work uh but he is like doing an incredible job of it i just think it's the same with like dan carlin in hardcore history i thought i thought that the way andrew's doing it would crush him the way he crushes dan carlin so dan has so much pressure on him to do a good job that he ends up publishing like two episodes a year so that pressure can be paralyzing the pressure of like putting out like strong scientific statements that that can be overwhelming now andrew seems to be just plowing through anyway if there's mistakes he'll he'll say there's corrections and so on yeah i just i wonder i actually haven't talked to him too much about it like psychologically how difficult is it to put yourself out there for an hour two a week of just non-stop dropping knowledge any one sentence of which could be totally wrong it could be a mistake and there will be yeah mistakes you know and i you know in the first edition of my book there were errors that you know we corrected in the second edition too but there will be probabilistically you know if you've got you know 10 facts per page of a book and you've got 350 pages odds are it's probably not going to be utter perfection out the gate and it will be the same way for andrew too but having the the reverence of um a humble mind and simply accepting the things that are wrong and correcting them and doing the right thing i know that that's his mentality i do want to say that i'm just kind of honored to be it's like it's a cool group of like scientific people that uh i'm fortunate enough to not be interacting with this is you and andrew and um david sinclair has been thinking about throwing his hat in the ring oh i hope so david is another one of those very special people in the world so it's cool because podcasts are it's cool it's a it's such a powerful medium of communication it's much freer than more constrained like publications and so on or it's much more accessible and inspiring than like i don't know conference presentations or lectures and it's it's a really exciting medium to me and it's cool that there's this like group of people that uh are becoming friends and putting stuff out there and supporting each other so it's fun to also watch how that's going to evolve in your case because it wonder it'd be too much is the answer to that like well i mean some of it is persistence through the challenges that we've been talking about which is like i think i've got a lot to learn yeah but i will persist look can i ask you some detailed stuff you mentioned that goodness go anywhere you wish with sleep uh so i'm a big fan of coffee and caffeine and i've been especially the last few days consuming a very large amount and i'm cognizant of the fact that my body is affected by caffeine different than the anecdotal information that other people tell me i seem to be not at all affected by it it's almost um it feels like more like a ritual then it is a chemical boost to my performance like i can drink several cups of coffee right before bed and just knock out anyway i'm not sure if it's a biological chemical or it has to do with just the fact that i'm just consuming huge amounts of caffeine all that to say uh what do you think is the relationship between coffee and sleep caffeine and sleep if there's an interesting distinction there there is a distinction so i think the first thing to say which is going to sound strange coming from me is drink coffee um the health benefits associated with drinking coffee are really quite well established now um but i think that the counterpoint to that well firstly the dose and the timing make the poison and i'll perhaps come back to that in just a second but for coffee it's actually not the caffeine so you know a lot of people have asked me about this rightful paradox between the fact that sleep provides all of these incredible health benefits and then coffee which can have a deleterious impact on your sleep has a whole collection of health benefits many of them venn diagram overlapping with those that sleep provides how on earth can you reconcile those two and the answer is that well the answer is very simple it's called antioxidants but it turns out that for most people in western civilization because of diet not being quite what it should be the major source through which they obtain antioxidants is the coffee bean so the the humble coffee bean has now been asked to carry the astronomical weight of serving up the large majority of people's antioxidant needs and you can see this if for example you look at the health benefits of decaffeinated coffee it has a whole constellation of really great health benefits too so it's not like caffeine and that's why i liked what you said this sort of separation of church and state between coffee and caffeine it's not the caffeine it's the coffee bean itself that provides those health benefits but coming back to how it impacts sleep it impacts sleep in probably at least three different ways the first is that for most people caffeine can make it obviously a little harder to fall asleep caffeine can make it harder to stay asleep but let's say that you are one of those individuals and i think you are and you can say look i can have three or four espressos with dinner and i fall asleep just fine and i stay asleep soundly across the light so there's no problem the downside there is that even if that is true the amount of deep sleep that you get will not be as deep and so you will actually lose somewhere between 10 to 30 percent of your deep sleep if you drink caffeine in the evening so to give you some context to to drop your deep sleep by let's say 20 i'd probably have to age you by 15 years or you could do it every night with a cup of coffee i think the fourth component that is perhaps less well understood about coffee is its timing and that's why i was saying the timing and the dose make the poison the dose by the way once you get past about three cups of coffee a day the health benefits actually start to turn down in the opposite direction so there is a u-shape function it's sort of you know the goldilocks syndrome not too little not too much just the right amount the second component is the timing though caffeine has a half-life of about five to six hours meaning that after five to six hours fifty percent of that on average for the average adult is still in the system which means that it has a quarter life of 10 to 12 hours so in other words if you have a coffee at noon a quarter of that caffeine is still circulating in your brain at midnight so having a cup of coffee at noon one could argue is the equivalent of tucking yourself into bed at midnight and before you turn the light out you swig a quarter of a cup of coffee but that doesn't still answer your question as to why are you so immune so i'm someone who is actually unfortunately very sensitive to caffeine and if i have you know even two cups of coffee in the morning i i don't sleep as well that night and i find it miserable because i love the smell of coffee i love the routine i love the ritual i think i would love to be invested in it it's just terrible for my sleep so i switched to decaf there is a difference from one individual to the next and it's controlled by a set of liver enzymes called cytochrome p450 enzymes and there is a particular gene that if you have a different sort of version of this gene it's called cyp 1 a 2 that gene will determine the speed of the clearance of caffeine from your system some people will have a version of that gene that is very effective and efficient at clearing that caffeine and so their half-life could be as short as two hours rather than five to six hours other people hands up matt walker um have a version of that gene that is not very effective at clearing out the uh the caffeine and therefore the half-life sort of sensitivity could be somewhere between you know eight to nine hours so we understand that there are individual differences but overall i guess the top line here is drink coffee um and understand that it's not the caffeine it's the coffee that's the benefit and the dose makes the poison is there some aspect to it that's it's like a muscle in terms of the all the combination of letters and numbers that you just said is there some aspect that if um i can improve the quarter life the half-life can decrease that number if i just practice like i drink a lot of coffee so like habit alters how your body is able to get rid of the caffeine not how the body is able to get rid of the caffeine but it does alter how sensitive the body is to the caffeine and it's not at the level of the enzyme degrading the caffeine it's at the level of the receptors that caffeine will act upon now it turns out that those are called adenosine receptors and maybe we can speak about what adenosine is and sleep pressure and all of that good stuff but as you start to drink more and more coffee the body tries to fight back and it happens with many different drugs by the way and it's called tolerance and so one of the ways that your body becomes tolerant to a drug is that the receptors that the drug is binding to these sort of welcome sites these sort of you know picture myths as it were that receive the drug those start to get taken away from the surface of the cell and it's what we call receptor internalization so the cell starts to think gee where's you know this there's a lot of stimulation going on this is too much so i'm just going to when normally i would you know coat my cell with let's just say five of these receptors for argument's sake things are going a little bit too ballistic right now i'm going to take away at least two of those receptors and downscale it to just having three of those and now you need two cups of coffee to get the same effect that one cup of coffee got you before and that's why then when you go cold turkey on coffee all of a sudden the system has equilibriated itself to expecting x amount of stimulation and now all of that stimulation is gone so it's now got too few receptors and you have a caffeine withdrawal syndrome and that's why for example with you know drugs of abuse things like heroin when people go into abstinence you know as they're sort of moving into their addiction they will build up a progressive tolerance to that drug so they need to take more of it to get the same high but then if they go cold turkey for some period of time the system goes back to being more sensitive again it starts to repopulate the surface of the cell with these receptors but now when they reuse and they fall off the wagon if they go back to the same dose that they were using before you know 10 weeks ago or three months ago that dose can kill them they can have an overdose even though they were using the same amount at those two different times the difference is that it's not the dose of the drug it's the sensitivity of the system and that's the same thing that we see with caffeine in terms of training the muscle as it were is the system becomes less sensitive can calibrate is there a time the number of hours before bed that's a safe bet to most people to recommend you shouldn't drink caffeine this many hours like is there an average half-life that you should be aiming at yeah or is this advice kind of impossible because there's so much variability there is a huge variability and i think everyone themselves you know to a degree knows it although i'll put a caveat on that too because it's slightly dangerous point so the recommendation for the average adult and who where is the average adult in society there is no such thing but for the average adult it would be probably cutting yourself off maybe 10 hours you know before so assuming a normative bedtime in society i would say try to stop drinking caffeine you know before 2 pm and just keep an eye out you know and if you're struggling with sleep dial down the caffeine and see if it makes a difference can i ask you about sleep and learning so how does sleep affect learning sleep before learning sleep after learning which are both fascinating kind of dynamics of the mind's interaction with this extra conscious state yeah sleep is profoundly and very intimately related to your memory systems and your informational systems the first as you just mentioned is that sleep before learning will essentially prepare your brain almost like a dry sponge ready to sort of initially soak up new information in other words you need sleep before learning to effectively imprint information into the brain to lay down fresh memory traces and without sleep the memory circuits of the brain and we know we've studied these memory circuits it will you know essentially become waterlogged as it were for the sponge analogy and you can't absorb the information as effectively so you need sleep before learning but you also need sleep unfortunately after learning too to then take those freshly minted memories and effectively hit the save button on them but it's nowhere near as quick as a digital system it takes hours because it's a physical biological change that happens at the level of brain cells but sleep after learning will cement and solidify that new memory into the neural architecture of the brain therefore making it less likely to be forgotten so you know i often think of sleep in that way as it's almost sort of future proofing information in in what way well it means that it gives it a higher degree of assurance to be remembered in the future rather than go through the sort of degradation that we think of as forgetting so the brain has in some ways by default you know there is forget and actually i would love to i was going to say sleep is relevant for memory in three different ways but i'm going to amend that and say this four different ways which is learning maintaining memorizing abstraction assimilation association and then forgetting which the last one sounds oxymoronic based on the form of three but i'll see if i can explain so sleep after learning then sort of you know sets the that information like amber in you know in solidification the third benefit however is that sleep we've learned more recently is much more intelligent than we ever gave it credit for sleep doesn't simply just take individual memories and strengthen them sleep will then intelligently integrate and cross link and associate that information together and it's almost like informational alchemy so that you wake up the next morning with a revised mind wide web of associations and that's probably the reason that you know you've never been told to stay awake on a problem you know and in every language that i've been quiet about that phrase or very something very similar seems to exist which means to me that this creative associative benefit of sleep transcends cultural boundaries it is a common experience across humanity now i should note that i think the french translation of that is much closer to you um i think you sleep with a problem whereas the british you sleep on a problem the french you sleep with a problem i think it says so much about the romantic difference between the british and the french but let's let's not go there um that's brilliant so such a subtle but such a fundamental difference yeah yeah goodness me sleep with the problem yes exactly right um so and we can sort of double click on any one of these and go in into detail but the fourth i became really enchanted by about eight years ago in our research which was this idea of forgetting and i started to think that forgetting may be the price that we pay for remembering and in that sense there is an enormous benefit to letting go you may be thinking that sounds ridiculous i don't want to forget in fact my biggest problem is i keep forgetting things but the brain it has a fight well we believe has a finite storage capacity we can't prove it yet but my suspicion is that that's probably true it doesn't have an infinite storage capacity it has constraints if that's the case we can't simply go through life being you know constantly informational aggregators unless you know we are programmed to say we've got a hard drive space of about 85 to 90 years and we're good and we can do that maybe that's true i don't think that's true i think forgetting is an incredibly good and useful thing so for example you know it's not beneficial from an evolutionary perspective for me to remember where i parked my car three years ago so it's important that i can remember today's parking spot but i don't want to have the junk kind of dna from a memory perspective of you know where my i parked my car you know two years ago um now i actually have a in some ways a problem with forgetting i'm and again i'm not trying to sort of be laudatory but you know i i tend not to forget too many things and i don't think that that's a good thing and um the there's a wonderful neurologist laurea who wrote a book called the mind of the mnemonicist and it was a brilliant book both because it was written exquisitely but he was studying these sort of memory savants who basically could remember everything that he gave them and he tried to find a in their armor and the first half of the book is essentially about him seeing how far he can push them before they fail and he never found that place he could never find a place where they stopped remembering and then in his brilliance he turned the question on its head he said not what is the benefit of constantly remembering but instead what is the detriment to never forgetting and when you start to realize his descriptions of those individuals it's probably a life that you would not want but it's fascinating both from a human perspective but also ai perspective there's a there's a big challenge in the machine learning community of how to build systems that are able to remember for prolonged periods of time lifelong continuous learning so where you build up information over time so memory is one of the biggest open problems in uh in ai and machine learning but at the same time the right way to formulate memory is actually forgetting because you have to be exceptionally selective at which kind of stuff you remember and that's where the step of a simulation integration that you're referring to is really important i mean we forget most of the things and and the question is exactly the cost of forgetting at the very edge of stuff that could be important or could not be how do we remember not those things like for example i've uh you know doing a podcast i've become cognizant of one feature of my forgetting that's been problematic which is i forget names and titles of books and so on so when i read i remember ideas i remember quotes i remember statements and like that's the space in which i'm thinking but when you communicate to others you have to say this person in this book said that it's the same thing with uh with like andrew huberman is masterful with this this is important academia remembering the authors of a paper and the title of the paper as part of remembering the idea and i've been feeling the cost of not not being able to naturally remember those things and so that that's something i need to sort of work on but that's an exact with faces yes very good at faces but not good with names so i am exactly like you and there is you know an understanding of that in the brain too we understand that there is partitioning of those in terms of the territory of the brain that takes care of faces and facts and places and they can be separate so i will never forget a face but you know and as i said i usually forget very little but for some reason names are a struggle i think in some ways because i'm probably just a slightly anxious person so when you first meet someone which is usually the time when a name is introduced you know you were saying you were sort of anxious maybe about sort of sitting down with me um but i find that a little bit you know activating and so it's not as though there's anything wrong with my memory it's just the emotional state i'm in when i'm first meeting someone yeah you know it's a little bit perturbing but i will never forget the face but um i completely relate to that because i almost don't hear uh people's names when they tell me because i'm so anxious yeah yeah but i i think there's certain quirks of social interaction that uh show that you care about the person that you remember that person that they mattered to you they had an impact on you and one of the ways to show that is you remember their name and but that's a quirk to me because there's a lot of people i meet have a deep impact on me but they i can't communicate that unless i know their name unless i know some of the um details that that we humans seem to use to communicate that will remember each other what i i remember well is the feeling we shared is the experience we shared what i don't remember well is the detailed labels of of those experiences and i need to certainly work on that i i don't know i think it's you know just allowing yourself to be innate and who you are is also a beautiful thing too i'm not suggesting it's not important to try and better oneself and but i also sometimes worry about the misery that that puts us in but like you i will i do struggle with him but i know for the first time when we met in the lobby um i know exactly what you look like i know that you were wearing headphones i know the shape and the size of those headphones you didn't have your black jacket on i know exactly what the weave of your shirt looked like and you know what your shoes look like and i knew exactly the height of your the end of your pants from the top of your shoes yeah and so those things i don't forget you know and i can that's fascinating remember when people i met people you know two years ago and i'll say oh yes we met there and um i remember you had those fantastic you know boots on i thought they were pretty great pair of boots you know and they're like how do you i didn't even remember what i was wearing that day yeah it's fascinating yeah i'm the exact the same way but you can't until we have neurolink or something like that we can't communicate that you remember all those things i know that's what i wanted so you have to be able to use uh tricks of human communication for that but so that i mean that's the it ultimately is a trick of like which to remember which to forget right and the forgetting is so it's so fascinating to say this i mean it seems to be deeply connected to that assimilation process so forgetting you try to fit all the new stuff into this big web of the old stuff and the things that don't fit you throw out i think the assimilation the way i've been thinking about it with sleep and it's particularly sort of dream sleep that we think can help with this assimilation is that during wake we have one version of associative processing what i mean by that is we see the most obvious connections so i think of wakefulness as a google search gone right whereas i see dream sleep as doing something very different i think dream sleep is a little bit like group therapy for memories that everyone gets a name badge and sleep gathers in all of the individual pieces of the day and it sort of starts to get you to forces you in fact to speak to the people not at the front of the room that you think you've got the most obvious connection with but to speak with the people all the way at the back of the room that at first you think i've got no obvious connection with them at all but once you get chatting with them you learn that you do have a very distant non-obvious connection but it's still a connection not the same and it's almost as though you're doing a google search where you know i input you know lex friedman and it doesn't take me to the first page of your home site page 20. it takes me to page 20 which is about some like field hockey game in utah yeah exactly it turns out that there actually is a link if i look at it it's a distant non-obvious one and to me i find that exciting because when you fuse things together that shouldn't normally go together but when they do they cause marked advances in evolutionary fitness it sounds like the biological basis of creativity and that's exactly what i think dream sleep and the algorithm of dream sleep is designed to do you know it's not a boolean like system where you have you know the sort of assumptions of true and false you know maybe it's more fuzzy logic system and i think rem sleep is a perfect environment within which we do you know it's almost like memory pinball you know you get the information that you've learned during the day and then you pull the lever back and you shoot it up into the attic of your brain you know this cortex filled with all of your past historical knowledge and you start to bounce it around and see where one of those things lights up and you build a new connection there and you build another one there too you're developing schemas and so in that way i think you could argue you know we dream therefore we are yeah so in terms of this line between learning and thinking through a new thing that seems to be deeply connected there's this legendary engineer named jim keller who keeps yelling at me about this he says it's very effective he likes to for difficult problems before bed think about that difficult problem we're not talking about like drama at work or all that kind of stuff no like a scientific for him engineering problem he likes to like intensely think about it and to prime his mind yes before sleep and then go to sleep and then uh he finds that uh the next day he's he's able to think much clearer and there's new ideas that come but also just i guess it's more well integrated and sometimes during the process of like he's able to like wake up and like see new insights that's right if he's deeply sort of aggressively thinking through a problem there's many scientific you know demonstrations of this you know the mendeleev with a periodic table of elements you know he was trying for months to understand i mean talk about an ecumenical problem of epic proportions here's your question today you have to understand how all of the known elements in the universe fit together in a logical way good luck take it was non-trivial at the time and he would try and try he was so obsessed with it he created playing cards with all of the different elements on and then he would go on these long train journeys around europe and he would just sort of deal these cards in front of them and he would shuffle them shuffling and shuffling and he would just try to see if he could find what the answer was and then so the story goes you know he fell asleep and he had a dream and in that dream you know all of these elements started to dance and play around and they snapped into a logical grid you know atomic weights etc etc and it wasn't his waking brain that solved the problem it was his sleeping brain that solved the impenetrable problem that his waking brain could not and there's been count you know even in the arts and in music some wonderful dreams you know frankenstein mary shelley's epic gothic novel came to her in a dream at lord byron's home and then we've got you know paul mccartney yesterday the song came to him in a dream he was uh filming um gosh what was the movie um i don't recall it i should be shocked because i'm from liverpool myself um and but he was on wimpole street in london um and filming and they he came up with that song the melody um in his sleep not to be outdone by the beatles and by the way let it be um also came from a dream that mccartney had people usually give it you know religious overtones you know mother mary comes to me speaking words of wisdom let it be if you've ever asked who mother mary is it's not the you know the biblical content it's his his mother it's it's it's mary mccartney yeah and she came to him in a dream and gifted him the song but the best story i've heard is um not to be outdone by the beatles the stones um keith richards uh who i think once was suggested that who was it was a comedian who was saying that in an interview with rolling stone keith richards suggested or inferred that young kids should not do drugs and they said well look young kids can't do drugs because you've done all of that but keith richards described he would always go to bed with his um guitar and a tape recorder um and then probably who would have a whole set of other things in the bed with him and who knows how many other people but anyway uh and then he said in his autobiography and i'm paraphrasing here but one morning i woke up and i realized that the tape had recorded all the way to the end so i rewound the tape and i hit play and there in some kind of ghostly form were the opening chords to satisfaction the most famous successful rolling stone song of all of all time yeah followed by then 43 minutes of snoring that riff came to him one of the most famous riffs in all of rock and roll came to him by way of a dream inspired insight so i think you know there is too many of those anecdotes and we've now got the site you know i don't rely on anecdotes a science we've now done the studies in the laboratory and we can reliably demonstrate that sleep inspires creativity inspires problem-solving capacity well the interesting thing is is it possible to some of the ideas that you talk about to turn them into a protocol that could be practiced rigorously so what jim keller espouses is saying not just the fact that sleep helps you increase the creativity but turn it into a process like literally like don't do it accidentally you know like uh like an athlete does certain things to optimize their performance they have a training routine they have a regimen of uh of like cycling and and uh sprints and long distance stuff in the same way thinking about your job as an idea generator in engineering space it's like this is good for my performance so like for an hour before bed think through a problem like every night and then use sleep to uh work through that problem i mean that he's the first person that i heard like of the people i really respect that do like what i do which is like programming engineering type work like using sleep not accidentally but with a purpose like using sleep you know that's just basically the difference between as you said a passive approach to it versus you know an an active deterministic or hope for a deterministic approach to it in other words that you are actually trying to harness the power of of sleep in a deliberate way rather than an unthoughtful way i still think that you know mother nature through it you know 3.6 million years of evolution has probably got it mostly figured out in terms of what information should be uploaded at night and worked through i think her algorithm is probably pretty good at this stage it's not to suggest though that you know we can't try to tweak it and nudge it you know it's a very light hand on the tiller is is what he's doing i i don't think there's anything wrong with that you know just like for example for me fasting has improved my ability to focus deeply and productivity significantly and in that same way you know it's possible that playing with these ideas of thinking before bed or some hours before better some playing with different protocols will have a significant leap over what mother nature naturally does so if you let your body do what it naturally does you may not achieve the same level of performance because mother nature has not designed us to think deeply about uh chip design for uh programming artificial intelligence systems so well she's gifted us the architecture and the capacity to do that what we do with that is you know is what life's experience dictates she gives us the blueprint to do many you know well if i were to sort of introspect and self analyze what mother nature wants me to do i think given my current lifestyle that i have food in the fridge and a bed to sleep on i think what mother nature wants me to do is to be lazy and so i think i'm actually resisting mother nature uh in because so many of my knees are satisfied and so i i'm i have to resist some of the natural forces of the body and the mind when i do some of the things i do so there's that dance um you know like i've been thinking about doing a startup and that's obviously going against everything that my body and mind are telling me to do because it's going to be basically suffering but the only reason i want as you know it will be over yes i but nevertheless there's some kind of inner drive that wants me to do it and then you start to ask a question well how do you optimize the things you can't optimize like sleep like diet like the people that you surround yourself with in order to maximize happiness and performance and all those kinds of things without also over optimizing and that's such an interesting idea from from a engineer so as you may know you don't often get that those kinds of ideas from engineers engineers usually just don't read books about sleeping they're usually like the the they're not they they're not the healthiest of people um i think that's changing over time especially silicon valley especially the tech sector people are starting to understand what's a healthy lifestyle but usually they're kind of on the insane side especially programmers but it's nice to hear uh somebody like that use sleep and use some of the things you talk about strategically yeah on purpose you know to that idea of not just trying to use what mother nature gave but seeing if you can do something more or different in a conservative mindset i would then pose the question at what cost because when you do something perhaps that deviates from the typical pre-programmed you know mother nature's program i suspect it usually comes at the cost of something else so maybe he is you know able to direct and focus his sleeping cognition on those particular topics that will gain him better problematic resolution the next day when he wakes up the question is though at what cost of the other things that didn't make it onto the menu of the finger buffet of sleep that night and is it that you don't process the emotional difficulties or events and therefore you are less emotionally resolved the next day but you are more problem resolved the following day and so i always try to think and i truly don't want to sound puritanical either about sleep and i think i've come off that way many a time especially when i started out in the public the tone of the book in some ways you know i look back and think could i have been a little softer and the reason was i i was that way back in when i started writing the book which was probably something like 2014 or 15. sleep was the neglected stepsister in the health conversation of the day and i was just so sad to see the amount of suffering and disease and sickness that was caused by insufficient sleep and for years before i've been you know doing public speaking and i'd tell people about the great things that happen when you get sleep people would say that's fascinating and then they would go back and keep doing the same thing about not sleeping enough and then i realized you can't really speak about the good things that happen it's like the news what bleeds leads and if you speak about the alarmingly bad things that happen people tend to have a behavioral change and so the book as a consequence i think probably came out a little bit on the strong side of you know trying to convince you know people you're trying to help a lot of people and that's a powerful way to help a lot of people i would i was genuinely trying to help people but you know certainly for some people who for whom sleep is not does not come easy then it was probably you know a tricky book to read too and i think i i feel more sensitive to those people now and empathetically connected to them um so i think the again the point was simply that i don't mean to sound too puritanical in in all of this and the same way with you know caffeine and coffee i am just a scientist and i am not here to tell anyone how to live their life that is not my job at all and life is to be lived to a degree and life is to be lived if you want to do a startup all i want to do is empower people with the understanding of the science of sleep and then you can make an informed choice as to how you want to live your life and i often no judgement on how anyone wishes to live their life i just want to try and see if the information that i have about sleep would alternatively change how you would think about your life decisions and if it doesn't no problem and if it does i hope it's been of use well maybe this is me trying to justify my lifestyle to you but dr seuss said you know you're in love when you can't fall asleep because reality is finally better than your dreams i love that quote too okay my sleeping uh schedule is uh complicated and it has to do primarily with the fact that i love basically everything that i do and that love takes a form that may not appear to be love from the external observer perspective because it often includes struggle it often includes something that looks like stress even though it's not stress it's like this excitement it's this turmoil and chaos of passion of struggling with the problem of being sad and down to the point even depressed of how difficult the problem is the disappointment that the last few weeks and months have been a failure and self-doubt all that mix but i i love it and a part of that is sometimes staying up all night working on a thing i'm really passionate about and that means sleep schedules that are just like you know sometimes sleeping during the day sometimes very often sleeping very little but taking naps that are like an hour or two hours or so on that kind of weird chaos and yeah now i'll also try to get give myself back up i was trying to like research yesterday is anybody else productive wild like this and there's of course a lot of anecdotal evidence and some of it could be just narratives that people have told to the public when in reality they sleep way more but there's a bunch of people that you know have not are famous for not sleeping much so uh on the topic of naps uh this i read this a long time ago and i checked this churchill was big on big naps and is actually just reading more about winston churchill's sleep schedule is very much like mine so i basically want to give myself the opportunity to at night to stay up all night if i want to and a good nap is a big part of that in the late evening like how often does this destroy social life completely but i i'll often take a nap in the late afternoon or the evening and that sets me if i want to stay up all night yeah and things like that like uh the i've read that nikola tesla slept only two hours a night edison the same three hours but he actually did uh the polyphasic sleep like where's just a bunch of naps what can you say about this madness of love and passion of loving everything you do and uh the chaos of sleep that might result in i love the seuss quote um and i've had that experience too like you i adore what i do you know if if someone you know gave you you know enough money to to live the rest of your life you know i've got a roof above my head rice and beans on the table um and they said you don't have to work anymore i would do nothing different i i would do exactly you know this sounds a little crass and i hope it doesn't sound this way but being a scientist is not what i do it's who i am when that's the case sleep working out showering and eating are the things that i do in between my love of fur with sleep yeah i fell for sleep like a blind roofer and and it was a love affair that started 20 years ago and i remain utterly besotted today it's the most beguiling thing in the world to me and i could easily and i have you know it's kept me up at night when my mind is fizzing with experimental ideas or i think i've got a new hypothesis or theory i will struggle with sleep i really will it it doesn't come easy to me because my mind is just so on fire with those ideas so i understand the the struggle but you know i couldn't advocate from a scientific perspective the schedule because the science just doesn't you know i would feel as though i'm doing you a disservice to say it's okay you know that that won't come with some blast radius some you know health consequences you know you can add margaret thatcher and ronald reagan to that list too both of them were very you know proud chess beaters of how little sleep that they get thatcher said four hours reagan something similar you know and i knowing the links that we now know between sleep and alzheimer's disease i've often wondered whether it was coincidental then that both of them died of the terrible disease of alzheimer's meaning you know maybe it doesn't get you by way of you know being popped out of the gene pool in a car accident because you had a microsleep at the wheel at age 32 or it doesn't get you at 42 with you know heart attack or even 52 with cancer or a stroke maybe it gets you in your 70s yeah i think the elastic band of sleep deprivation can stretch only so far before it snaps and it ultimately seems to snap you know nicole tesla uh i think he um goes to see he i think died of a coronary thrombosis i believe and there was a wonderful study done out of harvard where they took a group of people who had no signs of cardiovascular disease and what they found is that when they tracked them for years afterwards they were completely healthy to begin with those people who are getting less than six hours of sleep ended up having a 300 increased risk of developing calcification of the coronary artery which is the major sort of corridor of life for your heart when someone says you know he died of a massive coronary it's because of a blockade of the coronary artery you know and and tesla you know passed away from a coronary thrombosis we also know that insufficient sleep is linked to numerous mental health issues we know that churchill had a wicked battle with depression gosh my goodness he used to call it black dog that would come and visit him and i think many of his paintings he was exquisite painter but some of them would depict his darkness with depression as well you know edison is interesting people have argued that he would short sleep and he didn't put much value in sleep whether or not that's true we don't know but he was a habitual nappy you're right during the day i've got some great pictures of him on his inventor's bench taking a nap in fact i believe he set up nap cops around his house yeah so he could nap but what we also know a study again coming out of harvard just a couple of months ago demonstrated very clearly that polyphasic sleep is associated with worse physical outcomes worth cognitive outcomes and especially worse mood outcomes so from that sense you know sleeping like a baby is not perfect for adults there's a fascinating dance here of uh the mean and the extreme like the the average and the high performers so i um this this gets to like the meaning of life kind of discussion but let's go then so well and also happiness so when studying sleep and we're studying anything like diet and exercise i think you have to really get a lot more data about individuals to make a conclusive statement that's when people talk about like is meat red meat good for your bad for you right it's just so often correlated with other life decisions when you choose to eat meat or not my my sense is that whatever life decisions you make if they reduce stress and lead to happiness that's also going to be a big boost that needs to be integrated into the plots in the science right so the i'll give you an example of somebody who is unarguably seen as unhealthy my friend mr david goggins so he's clearly obviously almost on purpose destroying his body like and to say that he's doing the wrong thing or the unhealthy thing feels feels like feels wrong yeah and but i'm not sure exactly in which way he feels wrong one of the things i'm bothered by and again i apologize for the therapy sessions uh a framework of this but i'm bothered by the fact that a lot of people tell me or david that they're doing things wrong a lot of people in my life when they see me not sleep they'll tell me to sleep more now they're correct but one fundamental aspect that i'd like to complain about is not enough people almost nobody especially people that care for me will come to me and say you have a dream work harder like it's like the healthy thing should be a component of a life well lived right but not um not everything and i don't know what to do with that because uh you certainly don't want to espouse and just like you said when you were working in your book there is uh a belief you know sleep was a secondary citizen in in the full spectrum of what's a healthy life but at the same time i'm bothered by in silicon valley and all these kinds of uh work environments that i get to work with with engineers is there's to me too much focus on work-life balance what that usually starts meaning is like yeah yeah of course it's good to have a social life it's good to have a family it's good to it's good to eat well and sleep well but we should also discover our passion we should also give our chance to uh give give ourself a chance to work our ass off towards a dream and make mistakes and take big risks that in the short term seem to sacrifice health and i think you know you to come back to how you started about david goggins who i've never met but who i admire incredibly and have an immense reverence for the man um you said two things is it is it wrong to do those things to yourself and is it unhealthy to do those things to yourself i disagree with the former and i agree with the latter so from a health biological medicine perspective sleeping in the way that you know you've described or that other people may be sleeping in terms of insufficient amounts you know science now to your point too about inter-individual differences usually when i see a bar graph and a mean i usually say show me your variance yeah i want to see your variants in other words show me the distribution of that effect how many people were below the mean how many is it all tightly clustered around this one thing so it's a very robust effect or was this huge fan of effect where for some people there was no effect at all on other people there was a whopping effect and everything in between so i don't discount into individual variability but and i will come back to those two points about is it wrong and is it unhealthy in just a second when it comes to sleep we have found huge amounts of inter-individual differences in your response to a lack of sleep but one of the fascinating things so let's say that i take you and we're going to measure your attention your emotion your mood your blood pressure your blood sugar glucose regulation your autonomic nervous system and your different gene expression let's say i'm just going to measure a whole you know kaleidoscope of different outcomes brain and body and i find that on our measure of cognition on your attentional ability to focus you are very resilient you just don't show any impairment at all even after being awake for 36 hours straight does that mean that you are resilient in all of those other domains as well the answer is no you're not so you can be resilient in one but very vulnerable in another and we've we've not found anyone who isn't at least vulnerable in one of those domains meaning that it's somewhat safe to say that not getting sufficient sleep will lead to some kind of impairment in any one given individual it may not be the same impermanent but it's likely to be an impairment but to come back to the question i think it's wrong to tell anyone that it's wrong to do what they're doing even if they are compromising their sleep even if they're compromising their mental health you know as long as they're not hurting anyone else then i think the answer is that's that person's choice yeah but that's that person i'd like to push back further so you see the way you kind of said it yes you're absolutely right but i would like to say a stronger statement which is you should let go of that judgment of somebody is wrong and allow yourself to be inspired by the great heights they have reached so take yourself out of the seat of being a judger of what is healthy and not and appreciate the greatness of a particular human you you watch the olympics the kind of things that some athletes do to reach the very heights the olympics are taking years off their life they they suffer depression after the olympics often there it's the physiology disastrous yeah everything their personal life there's their psychology their physiology um everything it's a giant mess so the question is about life you know healthy now means you know longevity quality of life over a prolonged period of time you know optimal performance over a prolonged period of time but to me beauty is reaching great heights and there's a dance there that sometimes reaching great heights requires sacrifice of health and not like a calculation where you sat down on a sheet of paper and say i'm going to take seven years off my life for an olympic gold medal right no it requires more chaotic journey that that doesn't do that kind of calculus and i just want to kind of speak to the in the culture that struggles of what is healthy and not we want to be able to uh speak to what is healthy and at the same time be inspired by the great heights that humans reach no matter how healthy or unhealthy they uh they live yeah i agree with that i think if that's a flag you're hoisting i will definitely salute it because it really depends you know what are you trying to optimize for in your life and if you are i think the only danger potentially with that mindset is that if you look at many of the studies of old age and end of life most people say i never look back on my life and wish i worked harder i wish instead i'd spent more time with family friends and engaged in that aspect now i'm not saying though coming back to your point that that is the standard rubric for everyone i don't believe it is too and there are many things that you and i are both benefiting from today even in the field of medicine where people have sacrificed their own longevity for the quest of solving a particular medical problem and they died quicker because of their commitment because they wished to try and solve that problem in their pursuit of greatness scientifically and i now benefit am i grateful that they did that incredibly grateful you know it's a simpler demonstration of is this if tonight at 4 am in the morning i have a ruptured appendix i have an appendicitis i am incredibly grateful that there is an emergency team that will take me to the hospital at 4am in the morning they are awake they're not sleeping and they save my life and that is the that's part of what their life's mission and quest is and they saved another's life by in some ways shaving a little of their own off so i don't take i have no umbrage uh with that mentality at all i think you just have to be very clear about what you're optimizing for and my worry is that most people fall into the rat race and they never actually ask the question why am i doing this if you're just working nine to five or uh and you allow that nine to five to stretch into much longer but it's nevertheless a job that's kind of like wears you down that's one thing another thing is when it is a like you're it's a it's a dream it's a life mission accomplish and and for that i think as long as you know what it is that you could be doing to yourself and you are comfortable and a-okay with that i this i have no problem with that at all again as i said as a scientist i cannot should not and will not tell anyone what they should do with their life all i want you to be able to do is say okay now i understand more about the previously these were the you know known unknowns and these were the unknown unknowns and now i am slightly more cognizant i have more knowns than than i had before regarding my sleep and my health knowing that information do i still choose to make this decision and if that's what i offered then i think i've done my job that's all i want to offer is just added information into the decision algorithm and what you end up choosing as an output of that algorithm has nothing to do with me it's not my business and i will never judge anyone for it and as i said i'm immensely grateful for people who have sacrificed much in their lives to give me what i have so you're saying as long as the sacrifice sort of grounded in knowledge of you know what the sacrifice is that that sleep is important and that you're comfortable with it that is it is your conscious choice rather than feeling as though you're trapped or that you are just you haven't thought about it and you know you start that job at age 32 and then you wake up the next morning and you're 65 and you think where did my life go what was i doing that to me i would feel i would want to hug you and i would say i'm so i'm just so and i'm not sending i don't want to sound belittling here at all i would just not wish that for you i would wish that you could have you know thought about what it was that you're doing and not have that regret yeah so i guess i'm uh this is for you the listener i'm coming out of the closet here a little bit the fact that i enjoy the madness i live in so please do not criticize me embrace me i i understand the sacrifices i'm making i enjoy sleeping on the floor when i'm passionately programming all night and just pass out on on on the carpet i i love this life okay so it's it's uh it but it's definitely something i think about that there's a balance of strike uh where i just want you to have as much of it though of life see quality of life is important i should have said i want you to have as much high quality life and if high quality of life means i spend five decades on this planet but yet in that time i am thrilled every day i'm turned on every day by what i do and i reveled in this thing called my life's work i think that that is a 50-year journey of absolute delight and fulfillment that you should take i i think about my death all the time i meditate on death i'm okay to die today so to me longevity is not um it's not it's not a significant goal i'm so happy to be alive i don't even think it would suck to die uh today i i'm i'm as afraid of it today as i will be in 50 years i don't want to die as much today as i will in 50 years there's uh there's of course all these experiences i would like to have but i'm everything's already amazing it's like the lego movie so i i don't know so i to me i just want to keep doing this and um there's there's of course things that could affect you know like you mentioned dementia and these uh deterioration of the the mind or the body that can significantly affect the uh the quality of life right and so you want to uh as you're aware of that and you know that's the price you pay for the entry of into this magical you know kingdom that you are experiencing which is a lovely thing you know i i feel privileged too to i can't believe the life that i live it's incredible and just like you i don't i do i do i think about mortality a great deal i think a lot about death but i don't worry about death i i probably with the exception of the potential pain that comes before it that some people many people can't suffer that maybe concerns me but i actually think about mortality as a tool as i use it as a lens through which i can then retrospect and by placing myself at the point of future mortality i can then use it as a retrospective lens to focus and ask the following question is that anything i feel i would regret and therefore change in the life that i currently have now i that's the way i meditate and use mortality as a question is to try and course correct and focus my life i worry not about dying yeah but i like to think about death as a way to prioritize my life if that makes sense i don't know if that makes sense no it makes total sense to decide how do you want to live today so that in the future you do not regret the way you live today right and to place yourself in the future at your point of mortality is one way to i think as an exercise to retrospectively look back and not lose out on informed choices that you could otherwise lose out lose out on if you weren't thinking about mortality yeah it cl it clarifies your thinking uh is there um so i mentioned i sleep on the floor take naps and power naps and it's just kind of madness is there uh weirdness as to your own sleep schedule as a scientist that does incredible work has a lot of things going on has has to lead research has to write research has to be a science communicator also have a social life all those kinds of things is there certain patterns to your own sleep that you regret or you um or you participate in uh that you you find you enjoy um like is is there some like personal stuff uh quirks or things you're proud of that you do in terms of your sleep schedule the funny thing about being a sleep researcher is that it doesn't make you immune right to the ravages of a difficult night of sleep and i have battled my own periods of insomnia in my life too and i think i've been fortunate in ways because i know how sleep works and i know how to combat insomnia i know how to get it under control because insomnia in many ways is a condition where all of a sudden your sleep controls you rather than you control your sleep well yeah that's a beautiful way to put it yeah and i know when i'm starting to lose control and it's starting to take control and i understand how to regain but i've it doesn't happen now overnight it takes a long time so you've struggled with insomnia in your life i have not not all of my life i would say i've probably had three or four really severe bouts and all of them usually triggered by you know emotional circumstances by stress um stress that's connected to actual events in life or stress that's unexplainable will externally triggered yeah it's sort of what we would call reactive stress um and so that that's sort of point number one about the idiosyncrasies the point number two is that when you are having a difficult night of sleep as a sleep researcher you basically have become the woody allen neurotic of the sleep world because at that moment you know i'm trying to fall asleep and i'm not and i'm starting to think okay my dorsilateral prefrontal cortex is not shutting down my noradrenaline is not ramping down my sympathetic nervous system is not giving way to my parasite at that point you are dead in the water for the next two hours and nothing is bringing you back so uh there is some irony in that too i would say for myself though i if there's something i'm not proud of it has been at times railing against my chronotype so your chronotype is essentially are you a morning type evening type or somewhere in between yeah and there were times because society is desperately biased towards the morning types you know this notion of the early bird catches the worm maybe that's true but i'll also tell you that the second mouse gets the cheese yeah so i think one of my issues around you know is firstly people don't really understand cronotype because i'll have some people when i'm sort of out in the public they'll say look i struggle with terrible insomnia and i'll ask them is it problems falling asleep or staying asleep and they'll say falling asleep and then i'll say look if you are on a desert island with nothing to wake up for no responsibilities what time would you normally go to bed and what time would you wake up and they would say i'd probably like to go to bed about midnight and wake up maybe eight in the morning then i'd say so what time do you now go to bed and they'd say well i've got to be up for work early so i get into bed at 10. i say well you don't have insomnia you have a mismatch between your biological chronotype and your current sleep schedule and when you align those two and i was fighting that for some time too i'm probably mostly right in the middle i am desperately vanilla unfortunately in many aspects of life but this included i'm neither a strong morning type nor a strong evening type so ideally i'd probably like to go to bed around you know 11 10 30 11 probably somewhere between 10 13 11 and wake up you know i naturally wake up usually most days before my alarm at um 704 um and it's 704 because why not be idiosyncratic in terms of sitting i love it um and so i that's kind of awesome i've never heard about that that's that's amazing i'm going to start doing that now setting alarms like a little bit off the like yeah i know i'm never quite sure why we're the celebration of uniqueness yeah and i am quite the the odd snowflake in that sense too um so i would usually then try to force myself because i had that same mentality that if i wasn't up at you know 6 13 in the gym by seven that there was something wrong with me and i quickly abandoned that but if i look back if there was a shameful act that i have around my sleep i think it would be that for some years until i really started to get more detailed into sleep and now i have no shame in telling people that you know i will probably usually wake up around 6 45 naturally sometimes seven um when people are looking at me thinking you're a sloth you're lazy um and you know i don't finish my daily workout until you know i'm not working until probably nine o'clock in the morning i'm thinking what are you doing now i will work late into the day you know if i could i would work 16 hours that's my passion just like yours um so i don't feel shame around that but i have changed my mentality around that um it's complicated because i um i'm probably happiest going to bed at if i'm being honest like at 5 00 a.m that's fine you're just an extreme evening time but the problem is it's not that i'm ashamed for it it's uh i actually kind of enjoy it because i get to sleep through all the nonsense of like the morning and isn't that a beautiful thing like people are busy with their emails and and i just am a happy as a cow yeah and i wake up after all the drama has been resolved yeah and cows are happy and the drama has been resolved exactly so i but you know in society you do especially i mean this is what i think about is um you know when you work on a larger team especially with companies you are you know everybody's awake at the same time so that that's definitely that's definitely been a struggle to try to figure out just like you said um how to balance that how to fit into society and yet be optimal for your chronotype yup you have to sleep in synchrony with it and harmony um because normally what we know is that if you fight biology you'll normally lose and the way you know you've lost is through disease and sickness you said you suffered through several bouts of insomnia is there aside from embracing your chronotype is there um advice you can give how to overcome insomnia from your own experience right now the best method that we have is something called cognitive behavioral therapy for insomnia or cbti for short and you work with for people who don't know what it is you work with a therapist for maybe six weeks and you can do it online by the way i recommend probably jumping online it's just easiest and it will change your beliefs your habits your behaviors and your general stress around this thing called sleep and it is just as effective as sleeping pills in the short term but what's great is that unlike sleeping pills when you stop working with your therapist those benefits last for years later whereas when you stop your sleeping pills you typically have what's called rebound insomnia where your sleep not only goes back to being as bad as it was before it's usually even worse for me i think i found a number of things effective the first is that i had to really address what was stressful and try to come up with some degree of meaningful rationality around it because i think one of the things that happens there's something very talking about conscious states to come all the way back to um gosh i don't know i feel like we've only been chatting for like 20 minutes but you're going to tell me it's been a while it's been a while okay and desperately i'm i feel like terribly sorry okay but let's come back to consciousness where we started yeah um there is something very strange about the night that thoughts and anxieties are not the same as they are in the waking day they are worse they are bigger and i at least find that i am far more likely to catastrophize and ruminate at night about things that when i wake up the next day in the broad light of day i think it's nowhere near that bad man what were you doing it's not that bad at all so to gain firstly some rational understanding of my emotional state that's causing that insomnia was very helpful the second thing was to keep regularity just going to bed at the same time waking up and here's an unconventional piece of sleep advice after a bad night of sleep do nothing don't wake up any later don't go to bed any earlier don't nap during the day and don't drink any more coffee than you would otherwise because if you end up sleeping later into the the morning you're then not going to be tired at your normal time at night so then you're going to get into bed thinking well i had a terrible night of sleep last night and yes i slept in this morning to try and compensate but i'm still going to get to bed at my normal time but now you get into bed and you haven't been awake for as long as you normally would so you're not asleepy as you normally would be and so now you sit there lying in bed and it's another bad night and the same thing is you know if you go to bed any earlier so don't wake up any later wake up at the same time don't go to bed any earlier because then you're just probably your chronotype your biological rhythm doesn't want you to be asleep and you think well a terrible night i'm going to get into bed at 9 00 pm rather than my standard 10 you're just going to be lying in bed awake for that hour naps will take our double-edged sword they can have wonderful benefits we've done lots of studies on naps for both the brain and the body but they are a double-edged sword in the sense that napping will just take the edge off your sleepiness it's a little bit like a valve on a pressure cooker when you nap during the day you can take some of that healthy sleepiness that you've been building up during the day and for some people not all people but for some people that can then make it harder for them to fall asleep at night and then stay asleep soundly across the night so the advice would be if you're struggling with sleep at night don't nap during the day but if you are not struggling with sleep and you can nap regularly naps are just fine and we can play around with optimal durations depending on what you want just try not to nap too late into the day because napping late into the day is like snacking before your main meal yeah it just takes the edge off your sleep hunger as it were but that would be um so that's my unconventional second piece of advice regarding insomnia the third is meditation i found meditation to be incredibly powerful i started reading about meditation as i was researching that aspect of the book um many years ago and as a hard-nosed scientist i thought this sounds very woo-woo um this is sort of we all hold hands and sing come by and everything's going to be fine with sleep i read the data and it was compelling i couldn't ignore it and i started meditating and that was six years ago and i haven't stopped and i find meditation before bed incredibly powerful the meditation app companies were perplexed at this at first they want people to meditate during the day but when they looked at their usage statistics they found that they would have people in the morning meditating and then there's a huge number of people using the meditation app in the evening what they were doing was self-medicating this their insomnia and they finally rather than railing against it they started to see it as a cash cow rightly so yeah so i found meditation to be helpful having a wind down routine is the other thing that's critical for me i can't just go from because when my mind is switched on and i think you may be like this too if i get into bed that roller decks of thoughts and information and excitement and anxiety and worry is just whirling away and it's not going to be a good night for me so i have to find a wind down routine and that makes sense when you realize what sleep is like sleep is not like a light switch sleep is much more like trying to land a plane you know it takes time to descend down onto the terra firma that we call sound sleep at night and we have this for kids you know i don't have children but you know a lot of parents will say you know we have to have the bedroom sorry the bedtime routine you know you bathe the kids you put them in bed you read them a story you have to go through this routine this wind down routine for them and then they fall asleep wonderfully why do we abandon that as adults we need that same wind down routine so that's been the other thing that's been very helpful to me so um don't do anything different if you have a bad night of sleep keep doing the same thing manage your anxiety understand it rationalize it then meditation and then finally having some kind of disengagement wind down routine those are the four things that have been very helpful to me that's brilliant so the the regularities really do a lot of a lot of work against insomnia is there um is it possible to have a healthy sleep life without the regularities i say that because i'm all over the place yeah and i've gotten good in being all over the place so i'll often like what happens i'll go stretches of time there'll be sometimes a month where i my days are like this is embarrassing to admit but they're like just you and i here just you and i it's like 28 hours or 30 hour days yeah like i'll just go all the way around comfortably and happily i love it and now there'll be a nap i mean if you like add up the hours when i'm just like sleeping as much as i want it'll probably be like six hour average per 24 hours like that kind of yeah so it works out nicely maybe even seven hours i don't know but that it's obviously irregular and there's chaos in the whole thing right like sometimes it's shorter sleeve sometimes it's longer is that is that totally not a good thing do you think the best evidence that we have to speak to this question is people who are doing rotating shifts and unfortunately the news is not good um they usually have a higher incidence of many diseases such as depression diabetes cardiovascular disease obesity um stroke and [Music] and again i'm that's just me communicating the data that we we have and i'm not telling you that you should do anything different the other thing is that there's nothing in your biology that suggests that that's how your body was designed to sleep um it is a system that loves habit you know if if your circadian clock in your brain it's called the suprachiasmatic nucleus um sits in the middle of your brain had a personality trait it would be a creature of habit it loves habit that's how your biology is designed to work is through very archetypal prototypical expected cycles and when we when we do something different to that then you start to see some of the pressure stress fractures in the system but again to your point if that's something that you don't mind you know adopting and understanding and um then i think you should keep doing what you're doing it's complicated you of course have to be a student of your own body and explore it one of the reasons i want to have kids is kids in forces a stricter schedule i i think i definitely i've had i i definitely feel that i'm um not living the sort of data wise scientifically speaking the optimal life and me just living the way i want to live day to day is perhaps not the optimal way and there's certain things that i've seen very successful people that i know in my life when they get when they have kids they actually their productivity goes up they get their together there's a lot of aspects that everything yeah yeah the regularity i mean that creature is a habit that's the thing that that that's power and then you start to optimally use the hours you have in the day let me ask you about actually i just have one quick point on that too you know we often think about sleep as a cost but instead i think of sleep as an investment and the reason is because your effectiveness and your efficiency when you're well slept typically exceeds that when you're not and to me it's the idea of if i'm going to boil a pot of water why would i boil it on medium when i could boil it in half the time on high yeah and i sometimes worry that when i speak to fortune 500 companies and you know they're of this mentality of you know longer hours getting people to rise and grind the first point is that after about 20 hours of being awake a human being is as cognitively as impaired as they would be if they were legally drunk and the reason i bring that point up is because i don't know any company or ceo who would say i've got this great team they're drunk all the time but we often lord the airport warrior who's flown through three different time zones in the past two days is on email at 2am and then is you know in the office at six and i think there is some aspect not in all people but there is sort of some aspect of that slight sleep machismo and and that's not what you are very different you know you are driven by a purity of passion and a very authentic incredibly genuine goal of wanting to do something remarkable with your life that's not the issue i think i'm i'm speaking about it's just simply that i think the this notion of wanting to be awake for longer to try and get more done right can sometimes be at odds with the fact that you can actually get so much more done if you're well slept and it's this trade-off i actually admire people that take the big risk and work hard whether that means staying up late at night all those kinds of things but it cannot be in the in the framework in the context like what edison said which is sleep feels like a waste of time so like if you're not sleeping because you think sleep is stupid that's totally wrong but if you're not sleeping because you're deeply passionate about something that to me it's a it's a gray area of course but that to me is much more admirable and it's everything you're espousing is saying like whatever the hell you're doing you better be aware that sleep long term and short term is really good for you so if you're not sleeping you're sacrificing just make sure you're sacrificing for the right thing i i see vodka and getting drunk the same way i know it's not good for me i know i'm not gonna feel good days after i know it's gonna decrease my performance and there's nothing positive about it except it introduces chaos in my life that introduces beautiful experiences that i would not otherwise have it uh creates like this uh turmoil of social interaction that ultimately makes me happy that i've experienced them in the moment and later at the stories you get to meet new people it's like alcohol in this society is is a an incredible facilitator of that so like that's a good example of like not sleeping and drinking way too much vodka again it's this notion of you know life is to be lived to a degree but you know if you do have children um i think one of the other things that then maybe comes into the picture is the fact that now there are other people that you have to live for than yourself yeah but come on like once they're old enough like if you can't if you can't defend for yourself you're you're too weak get stronger it's going to be that kind of fatherhood yeah i got it i i'm understanding so much more about lex friedman than uh that's why you have to have your uh for for me that'd be my wife would be probably softer it's good cop bad cop because i think but of course actually because i don't have kids i've seen some tough dudes when they have kids become this the the like the softest the softies they become like they they do everything for their kids it becomes like it totally transforms their life i mean joe rogan is an example of that i just seen so many tough guys completely become changed by having kids which is fascinating to watch because it just shows you how meaningful having kids is for a lot of people although i would say having you know um chatted with joe for for some time um i think he is a delightful sweetheart independent of children i think don't get me wrong i don't want to be in a ring with him he would face me five ways till tuesday but um i think he's a desperately sweet man and a very very smart individual yeah i mean but he talks about the compassion he's gained from realizing just watching kids grow up that we were all kids at some point you you get a new new perspective i think just like me i still get this uh with him he's super competitive and like there's a certain way to approach life like you're striving to do great things and you're competitive against others and that intensity or that aggression um that can lack compassion sometimes in empathy and when you have children you get a sense like oh everybody was a child at some point everybody was as a kid and you see that whole development process it can definitely enrich um expand your your ability to be empathetic let me ask you about diet so what's the connection between diet and sleep so i do intermittent fasting sometimes only one meal a day sometimes no meals a day is there a good science on the interaction between fasting and sleep we have some data i would prefer more but we have data both on time restricted eating and then we have some data on fasting to a on time restricted eating i think that it has some benefits although the human replication studies have actually not borne out quite the same health benefit extent that the animal studies have been some disappointing studies one here close to where we are right now at ucsf recently so i think time restricted eating can be a good thing and there are many benefits of time restricted eating is sleep one of them no it doesn't seem to be because there are probably at the time that we're recording this three pretty decent studies that i'm aware of um two out of the three were in obese individuals one out of the three were in healthy weight individuals and what they found was that time restricted eating in all three of those studies didn't have any advantageous benefit to sleep it didn't necessarily harm sleep but it didn't seem to improve it when it comes to fasting though which is a different state we don't have too many studies experimental studies with long-term fasting the best data that we have is probably from religious practices and probably the most data we have is during ramadan where people will fast for 29 to 30 days from sunrise to sunset and under those conditions there are probably are probably five distinct changes that we've seen none of them seem to be particularly good for sleep the first is that the amount of melatonin that you release a melatonin is a hormone it's often called the hormone of darkness or the vampire hormone not because it makes you look longingly at people's necklines but it's just because it comes out at night yeah melatonin signals to your brain that and your body that it's dark it's nighttime and it's time to sleep those individuals when they were undergoing that regiment of fasting they the amount of melatonin that was released and when it was released the amount of melatonin decreased and when it was released came later that was the first thing the second thing was that they ended up finding it harder to fall asleep as quickly as they normally would otherwise the third thing was that the total amount of sleep that they were getting decreased the fourth fascinating thing was that a wake promoting chemical called erectin increased and this is why a lot of people will say when i'm fasting it feels like i can stay awake for longer and i can i'm more alert i'm more active and i'll come back to from an evolutionary perspective why we understand that to be the case and then the fourth factor is that fasting didn't decrease the amount of deep sleep that seemed to be unaffected it did however decrease the amount of rem sleep or dream sleep and we know that rem sleep dreaming is essential for emotional first aid mental health it's critical for memory creativity it's also critical for several hormone functions it's when you know if you there's direct correlations between testosterone you know testosterone release peaks just before you go into rem sleep and during rem sleep too so rem sleep is critical but so those are the five changes that we've seen none of them seem to be that advantageous for sleep but the fourth point that i mentioned which was orexin which is this wake promoting chemical and a good demonstration or a very sad demonstration of its power is when it becomes very deficient in the brain and it leads to a condition called narcolepsy where you know you you're just unpredictable with your sleep and you um so um so erection when it's in high concentrations keeps you awake when you lose it it can you know it can put you very much into a state of narcolepsy where you're sleeping a lot of the time in unpredictable sleep why on earth when you are fasting with the brain release awake promoting chemical and our answer is right now is the following the one of the few times that i mentioned before that we see animals undergoing insufficient sleep or prolonged sleep deprivation is under conditions of starvation and that is an extreme evolutionary pressure and at that point the brain will forego some it won't forego all but it will forego some of its sleep and the reason is so that it can stay awake for longer because the sign of starvation is saying to the brain you can't find food in your normal foraging perimeter you need to stay awake for longer so you can travel outside of your perimeter for a fur further distance and maybe you will find food and save the organism so in other words when we fast it's giving our brain this evolutionary signal that you are under conditions of starvation so the brain responds by saying oh my goodness i need to release the chemical that helps the organism stay awake for longer which is a raxiom so that they can forage for more food now of course your brain from an evolutionary perspective doesn't know about this thing called safeway that you could easily go to and break the fast but that's how we understand fasting and i think you know my dear friend peter tier has um has done a lot of work in this area too i think fasting and david sinclair is brilliant work goodness me what an individual too the work is pretty clear there that you know time restricted eating and fasting have wonderful health benefits time you know fasting is creates this thing called hermesis just like exercise and low level stress and sauna heat shock um and hormesis is a biological process i think as david sinclair has once said in simple layman's terms is what what doesn't kill you makes you stronger and i think the there is certainly good data that fasting and time-restricted eating has many benefits is sleep one of them it doesn't seem to be it doesn't seem to enhance sleep but it's interesting to to understand its effects on sleep i've um like i've fasted it's a study of nf2 i've once fasted 72 hours and another time 48 hours and i found that i got much less sleep and was very restful though i hesitate to say this but this is how i felt which is i needed less sleep i wonder if my brain is deceiving me because it feels like i'm getting a whole extra amount of focus for free and i wonder if there's long-term impacts of that because if i fast 24 hours get the same amount of calories one meal a day there's a little bit of discomfort like just uh maybe your body gets a little bit colder maybe there's just i mean hunger but the amount of focus is crazy yeah and so i wonder it's like i'm a little suspicious of that i feel like i'm getting something for free it's i'm the same way with sweetener like uh splenda or something it's like it's got to be really bad for you right because why is it so tasty right and i think yeah as we said for with biology you know if there's freeze again there's yeah there's often a cost too so but we at least understand the biological basis of what you're describing it's not that you you actually don't need less sleep it's that this chemical is present that forces you more awake and so subjectively you feel as though i don't need as much sleep because i'm wide awake and those two things are quite different it's not as though you your sleep need has decreased it's that your brain has hit the overdrive switch the overboost switch to say we need to keep you awake because food is in short supply so you mentioned uh during sleep there's assimilation all those kinds of things for learning purposes but there's also these uh you mentioned the five ways in which we become psychotic in dreams what do you think what do you think dreams are about what why do you think we dream what place do we go to when we dream and why are they useful not just um not just the assimilation aspect but just like all the crazy visuals that we get with dreams is there something uh you can speak to that's actually useful like why we have such fun experiences in that dream world so one of the camps in the sleep field is that dreams are meaningless that they are an epi phenomenal byproduct of this thing called rem sleep from which dreams come from as a physiological state so the analogy would be let's think of a light bulb that the reason that you create the apparatus of a light bulb is to produce this thing called light in the same way that we we've evolved to this thing called rem sleep to serve whatever functions rem sleep but it turns out that when you create light in that way you also produce something called heat it was never the reason that you designed the light bulb it's just what happens when you create light in that way and the belief so too was that dreaming was essentially the heat of the light bulb that rem sleep is critical but when you have rem sleep with a complex brain like ours you also produce this conscious epi phenomenon called dreaming i don't believe that for a second uh i and from a simple perspective is that i suspect that dreaming is more metabolically costly as a conscious experience than not dreaming so you could still have rem sleep but absent the conscious experience of dreaming was probably less metabolically costly and whenever mother nature burns the energy unit called atp which is the most valuable thing there's usually a reason for it so if what if it's more energetically demanding then i suspect that there is a function to it and we've now since discovered that dreams have a function the first as we mentioned creativity the second is that dreams provide a form of overnight therapy dreaming is a form of emotional first aid and it's during dream sleep at night that we take these difficult painful experiences that we've had during the day sometimes traumatic and dream sleep acts almost like a nocturnal soothing balm and it sort of just takes the sharp edges off those difficult painful experiences so that you come back the next day and you feel better about them and so i think in that sense dreaming it's not time that heals all wounds it's time during dream sleep that provides emotional convalescence so dreaming is almost a form of you know emotional windscreen wipers and i think and by the way it's not just that you dream it's what you dream about that also matters so for example scientists have done studies with learning and memory where they have people learn a virtual maze and what they discovered was that those people who then dreamed but dreamed of the maze were the only ones who when they woke up ended up being better at navigating the maze whereas those people who dreamed but didn't dream about the maze itself they were no better at navigating the maze so it's not just that you it's not it's sort of necessary but not sufficient it's necessary that you dream but it's not sufficient to produce the benefit you have to be dreaming about certain things itself and the same is true for mental health what we've discovered is that people who are going through a very difficult experience a trauma for example a very painful divorce those people who are dreaming but dreaming of that difficult event itself they go on to gain resolution to their clinical depression one year later whereas people who were dreaming just as much but not dreaming about the trauma itself did not go on to gain as much clinical resolution to their depression so it i think to me those are the lines of evidence that tell me dreaming is not epi phenomenal and it's not just about the act of dreaming it's about the content of the dreams not just the fact of a dream itself it's first of all it's fascinating it makes a lot of sense but then immediately takes my mind to from an engineering perspective how that could be useful in for example ai systems of uh if you think about dreaming as a important part about learning and cognition and filtering previous memories of what's important integrating them you know maybe you can correct me but i see dreaming is a kind of simulation of worlds that are not constrained by physics so like you you get a chance to take some of your memories some of your thoughts on your anxieties and play with them like construct virtual worlds and see how it evolves like to to play with those worlds in a safe environment of your mind safe in quotes because you can probably get into a lot of trouble with what the places your mind will go but in um this this this definitely is applied in much cruder ways in artificial intelligence so one context in which this is applied is uh the process called uh self-play which is uh reinforcement learning where uh agents play against it's itself or versions of itself and it's all simulated of trying different versions of themselves and playing against each other to see what ends up being a good the ultimate goal is to learn um a function that represents what is good and what is not good in terms of how you should act right you create a set of decision weights based on experience and you constantly update those weights based on ongoing learning but the the experience is artificially created versus actual real data so that's it's a crude approximation what dreams are which is you're hallucinating a lot of things to see which things are actually no i think it's and it's been a theory that's been put forward which is that dreaming is a virtual reality test space that is largely consequence-free what an incredible gift to give a conscious mind each and every night now the the conscious mind the human mind is very good at constructing dreams that are nevertheless useful for you like they're they're wild and crazy but they're such that they are still grounded in reality to a degree where anything you learn in dreams might be useful in reality this is a very difficult thing to do because it requires a lot of intelligence that requires consciousness uh this has been effectively recently been used in uh self-supervised learning for uh computer vision with the with the process of what's called data augmentation is that's a very crude version of dreams which is you take data and you mess with it and learn you start to learn how a picture of a cat truly represents a cat by messing with it in different ways now the crude methods currently are cropping rotating distorting all that kind of stuff but you can imagine much more complicated generative processes that start hallucinating different cats in order for you to understand deeply of what it means for something to look like a cat right what is the prototype of the archetype of the cat the archetype i mean that's a very difficult process for computer vision to you know to go from what are the pixels that are usually associated with the cat to like what is a cat in the visual space in the three-dimensional visual space that is projected on an image on a two-dimensional image what is a cat those are like fundamentally philosophical questions that we humans don't know the answer to like linguistically but when we look at a picture of a cat and a dog we can usually tell pretty damn well what's the difference right and i don't know what what that is because you can't reduce that to pointy ears or non-pointy ears furry or not furries yeah about the eyes it's been a long-standing issue in cognitive science cognitive neuroscience too it's how how does the brain create an archetype how does it create schemas that are have general applicability um but yet still obtain specificity that's a very difficult challenge we can do it we do it it's yeah rather bloody amazing it seems like part of the toolbox is this controlled hallucination which is dreams well it's a relaxing of the rigid constraints you know i often think of dreaming as you know it's from an information processing standpoint you know the prison guards are away and the prisoners are running a mark in a delightful way and part of the reason is because when you go into dream sleep the rational part of your brain called the prefrontal cortex which is the part it's like the ceo of the brain it's very good at making high-level rational top-down decisions and controlled actions that part of the brain is shut down during rem sleep but then emotional centers memory centers visual centers motoric centers all of those centers actually become more active in fact some of them are more active than when we're awake in the dream state that's fascinating so your brain from a neural architecture perspective is radically different its network feature is not the same as wakefulness and i think this is an immensely beneficial thing that we have at least two different rational and irrational conscious states that we do information processing in the rational the veritical the page one of the google search is wakefulness the more irrational illogical hyperassociative google page 20 is the rem sleep both i think are critical both are necessary that's fascinating and again fascinating to see how that could be integrated in the machines to to help them learn better and to uh to reason better and in some ways we also know it from a chemical perspective too when you go into dream sleep it is a neurochemical cocktail like no other that we see in the at the rest of the 24-hour state there is a chemical called noradrenaline or norepinephrine in the brain and you know of its cystic chemical in the body called adrenaline but upstairs in the brain noradrenaline is very good at creating a very hyper-focused attentive narrow it's sort of very convergent way of thinking to a point sharp focus that's the only thing the spotlight of consciousness is very narrow that's noradrenaline when you remove noradrenaline then you go from a high snr a high signal to noise ratio where it's just you and i in this moment i don't even know what's going on elsewhere i am with you nor adrenaline is present but when you go into rem sleep it is the only time during the 24-hour period where your brain is devoid of any noradrenaline it is completely shut off and so the signal-to-noise ratio is very different it's almost as though we're injecting a greater amount of noise into the neural architecture of the brain during dream sleep as if it's chemically brute forced into this relaxed associative memory processing state and then from an anatomical perspective just as i described the prefrontal cortex goes down and other regions light up so it is a state that seems to be very i mean if you were to show me a brain scan of rem sleep and and tell me that it's not rem sleep just say look based on the pattern of this brain activity what would you say is going on in this person's mind i would say well they're probably not rational they're probably not having logical thought because their prefrontal cortex is down they're probably feeling very emotional because their amygdala is is active which is an emotional center of the brain they're definitely going to be thinking visually because the back of the brain is lit up the visual cortex it's probably going to be filled with past experience and autobiographical memories because their their memory centers are lighting up and there's probably going to be movement because their motor cortex is very active that to me sounds very much like a dream and it that's exactly what we see in brain scanners when we put people inside of them one of the things i notice sleep effects is uh my ability to see the beauty in the world yeah so um what do you think is the connection between sleep in your emotional life your ability to love other human beings and love life yeah i think it's it's very powerful and strong so we've done a lot of work in the field of sleep and emotion and sleeping moods and you can separate your emotions into two main buckets um you know positive and negative and what's interesting is that when you are sleep deprived and the more hours that you go into being awake and the few hours that you've had to sleep your your negative mood starts to increase and and we we know which individual types of emotions are changing i've got a wonderful um postdoc in my lab called etti ben simon who's doing some incredible work on trying to understand the emotional individual emotional tapestry of affective meltdown when you're not getting sufficient sleep but let's just keep with two dimensions positive and negative yes the negative most people would think well it's the negative that takes the biggest hit when i'm sleep deprived it's not by probably in a log order magnitude larger is a hit on your positive emotions in other words you stop gaining pleasure from normally pleasurable things and it's a state that we call anhedonia and anhedonia is the state that we often call depression so depression to most people's surprise isn't necessarily that you're always feeling negative emotions it's often more about the fact that you lose the pleasure in the good things in life that's what we call anhedonia that's what we see in sleep and insufficient sleep and it happens quite quickly yeah it's kind of fascinating i um i think i do it's not depression but like it's uh it's a stroll into that direction which is when i'm sleep deprived i stopped being able to see the meaning in life the things that gave me meanings starts to lose meaning like stupid i it makes me realize how enjoyable everything is in my life because when i start to lose it when i'm severely sleep deprived you start to see how much life sucks when you lose it but that said when i'm just cognizant enough that like sleep fixes all that so i use those states for what they're worth in fact i personally like to pay attention to the things that uh bother me in during that time because they also reveal important information to me yeah i mean there's so i i find this when i fast combined with sleep deprivation i am clear to see with people clear and identifying the things that are not going right in my life or um people that i'm working with are not doing as good of a job as they could be doing um like people that are negative uh in my life i'm more able to identify them so i don't act on that it's a very bad time to act on those decisions but you get quite well made recording recording that information because i usually when i'm well rested and happy i see the beauty in everybody which can get you into trouble so yeah you have to balance those two things but yes it's fascinating there's an irony there too which is the fact that you know when you're well rested and well slept just as you said you see the the beauty in life and it sort of enlivens you and sort of gives you a quality of of life that's emotionally very different yet then we are contrasting that against the need for not getting enough sleep because of the beautiful things that you want to accomplish in life and i don't actually see them as you know sort of completely counter-intuitive or paradoxical because i still think that you can strive for all of the brilliant things that you are striving for to have the monumental goals the herculean challenges that you wish to take on and solve they can still enthrall you and excite you and stimulate you but because of the insufficient sleep that they can or that goal can produce it will shave off the beauty of life that you experience in between and again this is just about the trade-off i will say though that and this is not um applicable to your circumstance um we do know that insufficient sleep is very strongly linked to suicide ideation suicide attempts and tragically suicide completion as well and in fact in 20 years of studying sleep we have not been able to discover a single psychiatric condition in which sleep is normal and i think that that is a profound state i think it tells us so much about the role of sleep as a potential causal agent in psychiatric conditions i also think it's a potential sign that we should be using sleep as a tool yeah for the prevention of grave mental illness yeah it's both a cause and and a solution so yeah i i mean me personally i've gone through a few dark periods up quite recently and it was almost always sleep is not the cause but sleep is the catalyst from going to a bad time to a very bad time yeah and so it's it's definitely true and it's funny how sleep can just cure all of that there's actually a beautiful quote by an american entrepreneur called e joseph kosman who once said that the best bridge between despair and hope is a good night's sleep and i spill so much ink and hundreds of pages inelegantly trying to say the same thing in my book and he said it in one line and it's beautiful what do you think is uh we've been talking about how to extend this life how to make it a good life i've been talking about uh love what do you think is the meaning of this whole ride of life of life why do we want to make it a good one do you think there's a meaning do you think there's a answer to the why for me personally i think the meaning of life is is to eat is to sleep is to fall in love is to cry and then to die oh and probably race cars in between race cars well there's a whole topic of uh sex we didn't talk about so that's probably in there so should we do that we'll maybe if you'll have me back yeah that's the following i will give around next time we will do another three hours on sex alone has it been yeah it has been uh it's been over three hours gosh okay matt i i'm a big fan of your work i think you're doing really important work even despite all the things i've been saying about the madness of my own sleep schedule i think you're helping millions of people so it's an honor that you spend your valuable time with me and i can't wait until uh your podcast comes out i'm a huge fan of podcast i'm a huge fan of you and it's just an honor to know you and to get a chance hopefully in the future to work together with you you're a brilliant man and you're doing amazing things and i feel immensely honored to have met you to now know you and um to start calling you a friend thank you for what you do for the world and um for me included thank you matt take care thanks for listening to this conversation with matt walker and thank you to stamps.com squarespace athletic greens betterhelp and on it check them out in the description to support this podcast and now let me leave you with some words from nikola tesla who we discussed in this podcast as sleeping very few hours a night all that was great in the past was ridiculed condemned combatted and suppressed only to emerge all the more powerfully all the more triumphantly from the struggle thank you for listening and hope to see you next time you