Book Review: Why We Sleep?

A review of Why We Sleep by Mathew Walker.

Brief Summary 

A huge range of evidence demonstrates sleep deprivation is correlated with a huge range of physical and mental health problems: cancer, heart disease, car accident risk, obesity, anxiety and depression. Getting a better nights sleep is a universal panacea for many of these problems,

Better sleep also makes us more capable learners, more efficient workers, more able to deal with emotional strain and it even makes us more creative.

It follows that improving sleep should be a global health priority, since a better-slept population has enormous social benefits too – in terms of health, education and productivity outcomes.

However, despite the overwhelming evidence that we need more sleep, modern society is structured in a such a way that makes this difficult: our 24 hour, ever on culture, our education system which demands students start earlier than ever and work longer hours, and our anti-sleep macho-work ethic.

This book, based on over 20 years of research experience does a very convincing job of showing that our culture has it all  wrong where sleep is concerned – it seems that the easiest way to improve the quality of life for masses of people is simply for everyone to get another hour or so’s sleep every night!

Structure/ general readability 

The book is divided into four sections:

  1. This thing called sleep, which covers the definition of sleep, ‘what’ exactly sleep is, the stages of sleep, and how sleep varies across the life cycle.
  2. Why should you sleep: which outlines the wealth of evidence that sleep deprivation is bad for our physical and mental health.
  3. How and why we dream: basically it’s therapeutic and helps us be more creative.
  4. From sleeping pills to society transformed: outlines the social factors behind poor-sleep in modern society; rails against sleeping pills as a solution to sleep problems; and provides a new ‘vision for sleep in the 21st century’.

The book finishes with an appendix: 12 tips for health sleep.

The book is very readable – you can start at any section (I started with section four, and have only skimmed section three) and it will make sense. There are lots of very interesting case studies, and even the write ups of the experiments and the more technical stuff on sleep cycles and REMS is very accessible.

Most Interesting Bits (for me as a sociologist)

The most interesting sections for me were sections two and four: the research evidence on just how harmful sleep deprivation is, and just how anti-sleep our culture is. I’ll almost certainly be doing more in-depth summaries and commentaries on aspects of these sections of the book in the future!

Just some of the most interesting things I remember* include:

  • There really are ‘evening’ and ‘morning’ people – research suggests this is genetic. Walker theorizes that this is evolutionary – if half the tribe are ‘hard wired’ to sleep from 21.00 to 17.00 and the other half from 1.00 – 9.00 then that halves the overall sleep time of the tribe as a whole.
  • Sleep varies throughout the life-cycle – teenagers really do have a biological drive to stay awake into the early hours of the morning and get up later. Walker theorizes that this is adaptive – it gives teenagers a natural period away from their parents so they can ease into independence.
  • Thousands of studies over several decades suggest a link between sleep deprivation and a whole host of mental and physical health disorders.
  • A good night’s sleep is crucial to retaining information – it helps us retain information and ‘clears’ out our memory cache so that we can take in more fresh the next day. Thus, when revising, a good night’s sleep really is crucial!
  • Just 60 minutes sleep deprivation a night reduces our attention to the same level as having a had a few units of alcohol.
  • Drinking just a few units of alcohol in the evening is enough to prevent you going into REM sleep (NB you need all the sleep cycles to get a decent night’s sleep!)
  • There are more traffic accidents when the clocks go forwards and we all lose an hours sleep. This pattern reverses when they go back and we gain an hours a sleep.
  • Our education system really is messed up – expecting teenagers to come into school earlier and earlier is not realistic when they are hardwired to stay up later!
  • Poor sleep is probably the main reason behind the increase in mental health disorders.

*NB – A rough outline, from memory!

Research base:

This book has an outstanding research base. The author cites over a hundred research studies throughout the book, and is obviously familiar with thousands, as well as having over 20 years of experiencing researching the relationship between sleep and various variables.

The research base consists of mainly laboratory experiments on sleep trials (comparing an experimental group with a control group); but also some examples of large scale statistical comparisons (like the clocks going back and care accidents relationship), and case studies too.

Overall: 10/10


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