Impacts of lack of sleep
I've struggled with sleep for as long as I can remember. I have improved it considerably in the past year (still not perfect). Out of the dozens upon dozens of things I've tried, here's what I think made the most difference, in order of importance.1. Very consistent bedtime and wake up time. +/- 30 minutes, but ideally less. Obviously if you struggle with sleep you can't count on falling asleep at the same time, but work at it.2. Expose yourself to bright, outdoor light every morning.3. Keep the lights as dim as you can tolerate for ~2 hours before bed. Blue light is technically worse than red, but total light is way more important.4. Anything you do for ~1 hour before bed should be very passive. For me, reading is good, very particular kinds of TV is okay (can't be too stimulating), or something along those lines. Anything that requires decision making, social interaction, things that get you excited and so on are completely out.5. Breathe through your nose. It can be hard at first but it gets easier over time. If your nose is constricted you can exhale all your air, hold your breath until you feel the urge to breathe, and then draw in a big breath through your nose. It will open up your nasal passages. Do it a couple times if you need to. If you have sleep apnea that you can't fix that way get a CPAP.6. Meditation. And it's not really that doing 10 minutes of meditation during the day means you'll magically sleep better; it's more that you learn how to divert the noisy thoughts and focus on something very simple to help you relax at night.Also, sleep is a temporal problem. If you do everything perfectly for one day your probability of sleeping better at night will go up by some relatively small percentage. Which is discouraging. But if you really work at it for a month it will get significantly better. And by the same token, if you're in a good state, one or two days of disrupted sleep don't cause all that much damage.EDIT: 7. Forgot to mention this one: keep the room very cold. Matthew Walker (the guy who wrote Why We Sleep, which is a great book) recommends 65F.