Book Review: Why We Sleep by Matthew Walker

Why We Sleep: Unlocking the Power of Sleep and Dreams: Walker PhD ...
Picture taken from Amazon.

Author: Matthew Walker
Published: 2017

Goodreads: 4.4/5
Amazon: 4.7/5
(Aug 2020)

This is the first time I read an entire book about sleep. I came across Why We Sleep when searching for some highly-rated books to read during my free time. This book caught my eyes with a praising comment from Bill Gates on (here). Then I do a little bit of researching other sleep-related books and find that: while this one was rated by more than 60k people, the rest has only hundreds or at most several thousand each. That is a big gap. Thus, I decided to read it, not only to acquire new knowledge about sleep but also to answer for myself if this book’s popularity comes from Bill Gates’ comment or really from its exceptional quality.

At first, that was a bit overwhelmed. Although what we are talking about is sleep, a mundane activity that (almost) everyone does every day, it is actually quite complicated with the involvement of neurons and other complex components of the brain. There were a few dozen pages the author talks about the structure and operations of the brain that is connected to our sleep, in which part there are a handful of technical terms that I feel hard to understand. A bit frustrated, however, I’m glad I overcame this frustration and continued reading, as the following sections are really terrific.

Matthew Walker takes time to explain, one-by-one, how a good night’s sleep helps improve our brain development, memory, immune system, creativity, productivity, emotion, problem-solving skills, life-span, reproductive system, and reduce our chance of getting cancer, Alzheimer, depression, hypertension, cardiovascular diseases, diabetes, obesity, even bad genes, and DNAs. In short, the benefits of sleep are shown in nearly every aspect of life. Some of these gains are from REM (Rapid Eye Moment) while the others are from NREM (Non-rapid Eye Movement) sleep, these 2 are equally important. The interesting fact is: the distribution of REM and NREM sleep is different, while NREM sleep is dominant in the first hours of our bed-time, REM sleep mostly comes by a little later. Thus, if you sleep 6 hours instead of the recommended 8 hours for adults, you lose about half of your REM sleep time instead of just 25%. This lop-sided loss, as of its nature, results in a much worse consequence than in case both 2 types of sleep are reduced equally.

How about sleep lesser on weekdays and sleep-over during weekends? Not good. It is true that if we lack sleep tonight, our brain and body will seek for compensation the nights after. However, the brain never comes close to getting back all the sleep it has lost. That means if we lose sleep, we can never take it back fully.

Is it that only frequent practice of bad sleep that is bad, but one or two nights every now and then would not matter? No. Lacking sleep even for one night damages our bodies, and as stated above, this damage can never be fully healed.

May a nap at noon make up for a short sleep at night? Taking a short nap before 3 p.m is recommended, however, unfortunately, it cannot redeem for your bad night. Also, you should avoid day napping if you are having difficulty sleeping at night.

Is it true that we need less sleep at higher ages? Older adults still need a full night of sleep, just like young adults, but they, in general, failed to do so.

What are some actual numbers that describe the bad effects of not-enough sleep?

  • After 10 days of just 6-hour sleep per day, our concentration becomes equal to someone who has lost all of his sleep the night before, that is, an increase of 400% of microsleep compared to in the normal state. (“A microsleep is a temporary episode of sleep or drowsiness which may last for a fraction of a second or up to 30 seconds where an individual fails to respond to some arbitrary sensory input and becomes unconscious.” – quoted from Wiki). Microsleep is extremely dangerous in some cases like car-driving, and greatly reduces our concentration ability in general.
  • An extensive study of 7000 drivers in the US even reveals that compared to 8-hour sleep, those who sleep less than 4 hours the last night is 11.5 times more likely to be involved in a car accident.
  • More on traffic accidents: 1.2 million accidents are caused by sleepiness each year in the United States.

Some other facts around sleep:

  • People might have different circadian rhythm (circa means “around”, dian means “day”). Some might fit a bedtime from 9 pm (and then wake up at 5 am), some others might be more suitable for sleeping from 2 until 10 am. This difference is most easily observed through people of various ages, with the elders tend to go to sleep earlier than the youngsters. However, the circadian rhythm is not dependent only on age, gender, or preference, but it is mainly determined by genes. In other words, there is no way to tell one’s circadian rhythm by just looking at her.
  • The sleep of a pregnant mother can also affect the unborn child. Research has shown that the amount of lacked REM sleep for the mother has a correlation with autism of the child.
  • people who derived sleep consistently underestimated their degree of performance disability.
  • The sleep that alcohol and sleeping pills bring is not natural sleep, it does not produce the full benefits that a natural sleep does.
  • If you are sleep deprived, describe your symptoms to a psychiatrist without informing them of the lack of sleep, and the clinician will give clear diagnoses of depression, anxiety disorders, and schizophrenia.

Normally, I don’t give much attention to the appendix of a book, however, this one is different. This book has only 1 appendix, and it is very succinct and informative: the 12 tips for healthy sleep, those are:

  • Stick to a sleep schedule. (This is the most important one.)
  • Exercise is great, but not too late in the day.
  • 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.
  • Take a hot bath before bed.
  • Dark bedroom, cool bedroom, gadget-free bedroom.
  • Have the right sunlight exposure.
  • Don’t lie in bed awake.

My final thoughts

Why We Sleep is definitely an exceptional read. While for other types of self-help books, like books about habits, books about behaviors, you have multiple great choices to choose from, in term of books about sleep, I see Why We Sleep is out-standing. (Yes, I haven’t read any other book about sleep, but I feel somehow confident to give this bold assessment given this one’s popularity and quality.)

In the modern world, people are spending less and less time for sleep, which is an alerting phenomenon. For that reason, I would recommend everyone to read this book, or at least beware of the insights it offers, so that all of us will achieve more of health, successes, and happiness we deserve.

The book: Why We Sleep: Unlocking the Power of Sleep and Dreams by Matthew Walker

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