Why We Sleep

Why We Sleep by Matthew Walker

I read this hoping for some evidence-based motivation to prioritise sleep… Here’s what I took from it.

Sleeping well for about eight hours a night promotes good health and is a sign of good health. Learning and memory are particularly affected by sleep in a positive way. Sleep is when the brain does maintenance and so if you want a very healthy brain, you should prioritise sleep.

Some stuff in our normal environment messes with good patterns of sleep and we can take simple steps to correct most of this. Teenagers need to go to bed later and wake up later than everyone else. A normal pattern of sleep begins with deep sleep and shifts towards REM sleep later in the night. Sleep is cyclical and the cycles last about an hour and a half. Therefore getting five cycles in is optimal.

Things that help with a good sleep cycle include: daylight exposure on the skin and eyes early in the day, avoiding stimulants like caffeine and alcohol, allowing the darkness in the evening and avoiding blue light in particular, winding down before bed, keeping the bedroom for sleep and sex only not other activities, not eating too late, consistent timing. A warm shower before bed can encourage blood vessels near the surface of the skin to open up, helping the body to cool to induce sleep.

Two independent mechanisms govern sleep: the circadian rhythm and sleep pressure through melatonin. Even a short nap can significantly reduce the sleep pressure from melatonin accumulation.