Finished 22/11/2021

Why We Sleep: Unlocking the Power of Sleep and Dreams

Matthew Walker

⭐⭐⭐

I have to say it really sharpened my focus on sleep hygiene; I did not realize how important it is to sleep 8 hours a night for the brain. In particular I learned about the importance of the REM and NREM phases (the first “fortifies” memory connections, the second is more of an on-the-fly storage), sleeping 7-8 hours, the circadian rhythm, and the dangers of lack of sleep.

Key takeaway: regularize your sleep; set a time to go to bed and a time to wake up, and stick to them.

I also stumbled upon this debunking study: https://guzey.com/books/why-we-sleep/ so take this book with a grain of salt.

Notes

The less you sleep, the shorter you live.
Caffeine, alcohol, jet lag, and stress disrupt your regular sleep rhythm. Avoid them, especially coffee in the afternoon.
The circadian rhythm follows a pattern during the day and lines up with the level of adenosine, which rises in the evening. They are two separate factors with different curves.
You cannot catch up on lost sleep. The effects of several short nights cause distraction and fatigue even if you rest on the weekend.
Sleep changes across ages: in particular, teenagers have a circadian rhythm shifted later, and early school start times harm them. Older adults tend to sleep less, sleep more poorly, and wake up earlier due to changes in their rhythms.
Sleep helps you work better, lifts your mood, and above all: microsleep at the wheel is extremely dangerous, those couple of seconds when you nod off.
Lack of sleep causes a host of problems, from heart attacks to weight gain, premature death, depression, and so on. Not recommended.
The nighttime “dance” between REM and NREM is very interesting. We alternate storing thoughts with cleaning and reordering during REM.
A cool, quiet, LED-free environment helps you sleep. Melatonin is not very effective because it works only if you are already sleepy, but it can help. Prescription sleep pills are problematic; they block receptors but do not generate natural sleep architecture, and they may cause health problems.

Sleep hygiene tips

Stick to a sleep schedule
Exercise is great, but not too late in the day. Try to exercise at least thirty minutes on most days but not later than two to three hours before your bedtime.
Avoid caffeine and nicotine.
Avoid alcoholic drinks before bed.
Avoid large meals and beverages late at night.
If possible, avoid medicines that delay or disrupt your sleep.
Don’t take naps after 3 p.m.
Relax before bed. Don’t overschedule your day so that no time is left for unwinding. A relaxing activity, such as reading or listening to music, should be part of your bedtime ritual.
Take a hot bath before bed.
Dark bedroom, cool bedroom, gadget-free bedroom.
Have the right sunlight exposure. Daylight is key to regulating daily sleep patterns. Try to get outside in natural sunlight for at least thirty minutes each day. If possible, wake up with the sun or use very bright lights in the morning.
Don’t lie in bed awake.