This book gives a comprehensive scientific overview of sleep. Although there are still many unanswered questions, there’s been a lot of research lately and this book sums it up.
Sleep is a very necessary function of life. Every living organism requires it, although in different amounts, and total lack of sleep very quickly leads to death. However it’s still unclear exactly why sleep is so important.
There are two types of sleep: REM (rapid eye movement) and NREM sleep. REM sleep is a much lighter form of sleep where you’re closer to the awake state, and is also when you dream; NREM is a much deeper sleep. You can distinguish the type of sleep easily by measuring brain waves.
Sleep deprivation is really bad. You don’t even need total deprivation, even six hours of sleep a day for a few nights is as bad as pulling an all-nighter. When you’re sleep deprived, you’re a lot worse at learning things, controlling your emotions, and you’re also more likely to get sick and more susceptible to cancer.
Dreams aren’t that well understood, but they seem to consolidate memories, including moving them from short term to long term storage. REM sleep especially lets your brain find connections between different ideas, and you’re better at problem solving immediately after.
Insomnia is a really common problem in our society, in part due to it being structured to encourage sleeping less. Sleeping pills are ineffective at best (prescription ones like Ambien and Benzodiazepines are actually really harmful), the recommended treatment is behavioral, like sleeping in a regular schedule, avoiding caffeine and nicotine and alcohol, don’t take naps, avoid light in the bedroom.
My parents always told me it’s bad to stay up so late, but science doesn’t really support this. Different people have different chronotypes, which are determined by genetics (and somewhat changes by age). It’s okay to sleep really late, as long as you maintain a consistent sleep schedule.
Overall I learned a lot from this book but it’s a fairly dense read, with lots of information about different topics, and it took me over a month to finish it.