Why We Sleep – Matthew Walker
- We need 8-9h of ‘sleep opportunity time’ a night, consistently
- A repeated message from the book was that you can’t make up for
lost sleep later. You can’t repay a sleep debt. Rather, the best
way is not to go into debt in the first place
- Not enough sleep is linked with many health conditions. Cardiac
stress, increased heart attack rates, Alzheimer’s disease
and ~50% increased cancer and tumour growth rates.
- Without enough sleep, your body is rekt. There’s all the diseases
above (and more I skimmed through!) Then theres the impaired
cognitive performance the next day.
- Ten days of seven hours a night gives same result as 1 day no sleep
- Being sleepy is equivalent of being drunk, especially when driving.
- If drunk driving and sleepy driving are 4-5x risk of accident,
sleepy drunk driving is 30x as likely – the factors multiply
- Teenagers have delayed sleep cycle (it’s more into the night),
while older people have sleep cycle moved forward.
- Blue-light LEDs delay melatonin release by 2-3 hours …don’t watch
late night TV!
- Two cycles in the body coincide – there’s your melatonin cycle
(goes up and down) and then the other one that gets you up in the
- Sleeping pills are evil and you should never never use them
- NREM sleep is in the first part of the night, REM in the second. If
you get up early consistently, you cut REM sleep. If you go to bed
late consistently, you cut NREM.
- Sleep transfers memories from short term to long term storage. A bad
sleep after learning something will affect retention of
knowledge to a serious degree. That’s just one reason to get more
sleep – you’ll actually remember what you learn.
- Sleep boosts your immune system pretty hard. You’re much less
likely to get sick if you sleep a lot.
- Drinking alcohol even 3 days after you learn something will torpedo
your sleep for that night and really damage the retention of that
knowledge. If you have to drink, lunchtime is the time for it.
- There’s devices available that can optimise your sleep. There’s
stuff that measures your sleeping brainwaves and tries to enhance
it. There was a suit that keeps your thermally controlled. There was
LED lights that adjust depending on time of day.
- Get an eyemask when sleeping
- Light 1% strength of daylight can have up to 50% melatonin
- Emotional control is shot when you don’t sleep enough. The
equivalent of tired kids having tantrums continues as you get older,
into tired people snapping at each other
- Adenosine is the ‘sleep pressure’ chemical
- Use a cold room for sleeping (~18 degrees Celsius optimal)
- No caffeine after 9:30am. It takes a surprisingly long time to wear