love this little to the spinal cord here I'm this here is the high performance and right under their he's a whole raft interesting structures not least the biological clock biological clock told us when it's good to be up when it's good to be asleep and what that structure does is interact with the whole raft of other errors within the half hour miss that from high-performance the ventrolateral preoptic nucleus with those combined and they send projections down to the brainstem here the brainstem then projects forward and bay leaves the cortex this wonderfully wrinkly over here with your transmitters the keep us awake and essentially provide us with our consciousness so sleep arises from a whole raft of different interactions within the brain and essentially sleep is turned on an officer was also for range of interactions in here okay so we have got to we've said that sleep is complicated and it takes 30 two years ago of our life we were having to explain his what sleep is about so why dubiously and it would surprise any view that of course the scientists we don't have a consensus there are dozens of different ideas about why you sleep and I gotta outline three of us the first these so that the restoration ID and its somewhat intuitive essentially all the stuff we went up during the day we restore we replace we rebuild during the night and indeed as an explanation it goes back to aristotle's so that's what two thousand three hundred years ago he's gone into fashion it's fashionable moments because what's been shown is that within the brain a whole raft of jeans have been shown to be turned on only during sleep and those genes are associated with restoration and metabolic pathways so is good evidence for the whole restoration hypothesis what about energy conservation begin perhaps intuitive um I'm you essentially sleep to save calories now when you do the sums that which doesn't really pan out if you compare individual who has slept at night all stayed awake and hasn't moved very much the energy-saving sleeping is about 110 calories tonight now that's equivalent of hot dog bun now I would say perhaps hot dog bun is kind of a meager return for such a complicated demanding behaviors sleep so I'm less convinced by the the energy conservation idea but the third idea of unquote attract to which is brain processing and memory consolidation what we know is that if North you try to learn the task and you sleep deprived individuals the ability to learn that task is smashed its it's really hugely attenuated so sleep in memory consolidation is also very important however it's not just the laying down a memory and recording it what's turned out to be really exciting is that our ability to come up with normal solutions to complex problems is hugely enhanced by night to sleep in fact it's been estimated to give us a threefold advantage sleeping at night and enhances our creativity what seems to be going on is a in the brain those new all connections the importance the Senate connections are important are linked and strengthened well those that the less important 10+2 so the fade away and be less important okay so we've had three explanations for why we might sleep and I think the important thing to realize is that the details will fare in its probably be /c for multiple different reasons but sleep is not an indulgence it's not some sort of thing that we can taken for traffic casually I'm I think sepals once like into upgrade from economy to business class you couldn't of it's not it's not even an upgrade from economy to first class the critical thing to realize is that if you don't sleep you don't fly essentially you never get there and what's extraordinary about much about society these days is that we are desperately sleep-deprived so let's now look at sleep depravation huge sectors of society a sleep-deprived and lets look at our sleep on Twitter so in the 1950s good data suggests that most of us were getting around about eight hours of sleep a night nowadays we stick 1/2 to 2 hours less every night so we're in the sort of six and a half hours every night leak for teenagers its it's worse much worse they need nine hours full bring performance and many of them on a school night only getting five hours of sleep it's simply not enough if we think about other sectors of society the aged a if you are etude then your ability to sleep in a single block is somewhat disrupted and many sleep again less than five hours a night shift work shift work is extraordinary perhaps twenty percent to the working population and the body clock does not shift to the demands it working at night it's locked onto the same light dark cycle the Restless so when the porch if work is going home to try and sleep during the day desperately tired body clock is saying wake up this is the time to be awake so the quality of sick you get is a night shift work is usually very poor again you that's a five-hour region and then of course tens of millions of people suffer from jet lag so so who here has jetlag well my goodness gracious will thank you very much indeed for not falling asleep because that's what your brain is craving one other things that the brain does is indulge in Mike receipts this infantry falling asleep you have essentially no control over it now Micah seats can be some somewhat embarrassing but they can also be deadly it's been estimated that 31 percent to drivers will fall asleep at the wheel at least once in their life and in the US the statistics a pretty good a hundred thousand accidents on the freeway have been associated with tiredness lost the vigilance and falling asleep hundred thousand two years school me at another level have terrorist we dip into the tragic accidents at chernobyl and indeed the space shuttle Challenger which were so tragically lost and investigations that followed those disasters poor judgment as a result of extended shift work and looks a vigilance and hardness was attributed to the each a big chunk of with those those disasters so when you're tired you lack sleep you have poor memory you have for creativity you have increased impulsiveness and you have overall poor judgment my friends it's so much worse than that if you are retired brain the brain is craving things to make it up so drugs stimulants caffeine represents V Stephen to have choice across much of the Western world much of the days fueled by caffeine and if you're really naughty tired brain nicotine and of course you're fueling the waking state with these stimulants and then of course get through eleven o'clock at night the braces to self were actually I need to be asleep very short be what do we do about that when