“Why we sleep”-A review of Dr. Matthew Walker’s book

Updated: Sep 30, 2021

Why do we sleep? As we know, in the tribal/survival sense, when we’re sleeping we can’t hunt, gather, eat, reproduce, or defend ourselves. But Dr. Walker concludes that the evolutionary positive impact of sleep is far greater than these downsides. Sleep produces neurochemicals that improve our brains in various ways. In other words, sleep enhances our evolutionary fitness in ways most of us can’t see.

Sleep is an essential biological function that occurs in humans and every living animal; from armadillos who spend most of their day sleeping (about 18.5 hours every day), to giraffes who receive only two hours. Between them, there’s us humans, who are supposed to sleep seven to nine hours (even though most of us don’t). This makes sleep an inseparable function that takes one third of our lives. But, for years and years, sleep kept being a mystery: we knew we needed it but didn’t know why. In his book Why We Sleep, Dr. Matthew Walker adds light to this topic. To be honest, while reading this book I slept...a lot, but that’s just an awesome book doing its job.

Dr. Matthew, a neurobiologist, found a way of being more productive, healthier, clever and most importantly happier- a good night's sleep. As a generous person who understood the importance of sleep, he didn’t mind sharing this with all of us around the world and made a lot of lives better. The book is put together in such a way that makes you read it very quickly: it’s fun, interesting and interactive. But at the same time, it covers nearly everything about sleep; starting from sleep basics, circadian cycle, the impact of different things in sleep and the impact of sleep in life, dreams, sleeping pills and also finding solutions to these problems. There’s simply a lot of important information in these three hundred sixty-eight pages.

What I mostly love about this book is the fact that it is fun to read for a scientist or a doctor but it is also really easy to understand even for the people who are not involved in this field at all. Every book section is explained clearly and supported by experimental or epidemiological evidence, without ever becoming too deep for the non-specialist or too superficial for a scientist. It consists of four chapters: The thing called sleep, Why should you sleep, How and why we dream and From sleeping pills to society transformed. As Dr. Matthew mentioned in the beginning of the book, it can be read as a whole or readers can choose specific chapters only: still very powerful and easy to understand.

Interestingly, the book doesn’t totally answer the question of why we sleep. Maybe as William Dement said “The only solid reason we need to sleep is because we get sleepy.” But the book gives a lot of evidence of the consequences of lack of sleep on our health and life and therefore indirectly answers the big question “Why we sleep”. The number of road-traffic and workplace accidents due to tiredness is bigger than the number attributed to drinking and drugs combined together. Poor sleep is associated with coronary artery disease, especially in people over their forties who get less than six hours of sleep. Reducing sleep to 5-6 hours per night disrupts leptin and ghrelin signalling, which leads to increased food intake and is also associated with risk for diabetes. The long list of risks also include cancer, Alzheimer’s disease, a reduced immune response, infection, depression, schizophrenia, and infertility.

What can we do about it? Dr. Walker has answers for this as well. He suggests 12 tips to help improve sleep hygiene and change attitudes: 1. Stick to a sleep schedule

2. Don’t exercise too late in the day

3. Avoid caffeine & nicotine

4. Avoid alcoholic drinks before bed

5. Avoid large meals and beverages late at night

6. Avoid medicines that delay or disrupt your sleep (where possible)

7. Don’t nap after 3pm

8. Make sure to leave time to relax before bed

9. Take a hot bath before bed

10. Have a dark, cool (in temperature), gadget free bedroom

11. Get the right sunlight exposure

12. Don’t stay in bed if you (really) can’t sleep.

Completed, as it is, with a lot of information and practical advice, this book became one of my top favorites and most interesting books I have ever read. It gave me another perspective on sleep and made me think of my own unhealthy habits and try to change them. It helped me give more importance to sleep, and I can literally say it changed my life for better.

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