Book Review: Why We Sleep by Matthew Walker

Quote of the book

“It is time for us to reclaim our right to a full night of sleep, without embarrassment or the damaging stigma of laziness”

5 key points

  • In the Northern Hemisphere, when the clocks go forward by one hour, there is an increase in the number of heart attacks the next day. The opposite happens in October when the clocks go back – one hour of sleep makes a difference!
  • Sleeping is more powerful than doing an all-nighter before an exam, as it helps to form long term memories and make people more creative.
  • There are more car accidents caused by drowsiness from sleep deprivation than caused by both alcohol and drugs.
  • Dreams reflect what the individual is emotionally bothered by and not whatever activity or events occurred during the day.
  • Muscle activity is eliminated whilst you dream – you are essentially paralysed during REM sleep. This is so that you can dream safely without acting out your dreams.


Are you a morning lark or night owl? Do you prefer sleeping later and waking up later or sleeping earlier at night and waking up earlier? One of the topics that Matthew Walker touches upon in this book is how the synchronisation of work and school hours is disadvantaged against those who prefer the former; even if the night owls are physically awake at the start of a standard working day, their brains are still in a sleep-like state for the morning. This is socially misconstrued as laziness, when really it is just a different internal rhythm of wakefulness.

This book was very accessible, despite being a science book. Walker’s writing is engaging and at times light-hearted. It is not necessary to have scientific knowledge to follow along as Walker provides clear explanations of terms used. It would be of particular interest to those interested in science, society, the human mind, neuroscience, psychology, or medicine – though anyone with an interest in how sleep affects their wellbeing will benefit from it.

The book is full of interesting facts about human sleep, such as that performance falls once people have been awake for 15 hours (say, from 07:00 to 22:00). Additionally, if someone sleeps for 7 hours a night for 10 days in a row, this has the same negative effect on brain functionality as not sleeping for 24 hours. Moreover, caffeine has a half life of 5-7 hours, which means that 50% of the caffeine consumed at, say, 13:00, is still active in the body at 18:00-20:00. The reader will certainly learn a lot from reading even only a section of the book.

Walker demonstrates, with a series of experiments and scientific evidence, that there is nothing in human biology that doesn’t benefit from good sleep. It can be considered like a form of medicine that reduces the risk of many ailments such as cancer, Alzheimer’s, psychiatric illnesses, and diabetes, to name only a few. As Walker points out, even the World Health Organisation has called nighttime shift work a “probable carcinogen” because of its impact on the body.

This book is not a ‘How to Sleep’ guide, though Walker does include some tips at the end of the book on how the reader can improve their sleep. Instead, this is a science and evidence backed book about why humans sleep in the first place even though sleeping is such a strange concept, but equally why it is so important to human survival and longevity. It can be approached from many angles, such as science, public policy, healthcare and sociology.

It was particularly interesting how Walker explains the impact of modern life on sleeping patterns. For example, excessive light before sleeping, the wrong temperature of bedrooms, caffeine, alcohol, and alarm clocks are all factors which destroy natural sleeping patterns. This is in addition to unhealthy societal attitudes towards getting a full night’s rest which result in sleep neglect. Walker makes some suggestions for how society, public policy, organisations and individuals can make changes to improve sleep, including flexible working hours and a core collaboration window in the workplace. This was interesting to read in the era of covid-19, when many workplaces have adopted flexible working patterns and witnessed the results.

With compelling evidence and examples of experiments, Walker encourages the reader to feel empowered to protect their sleep. I found this to be the most powerful feature of the book – it is relatable and persuasive to encourage people to prioritise their health and wellbeing. This book is a must-read.

Overall rating: ⭐⭐⭐⭐⭐

Get the book | Official website | Goodreads

Published by sharemylibrary

Non-fiction book reviews, summaries, and recommendations

3 thoughts on “Book Review: Why We Sleep by Matthew Walker

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: