In the latter half of 2019, it seemed like every month I was coming across references to Matthew Walker’s book, Why We Sleep: The New Science of Sleep and Dreams. Whether it was from podcasts, YouTube videos, or on a tour of a biotech company, the book was everywhere. It has exploded in popularity in the last year, receiving positive reviews from multiple news outlets and Bill Gates’ personal blog, and Walker’s subsequent TED talk has over 12 million views between YouTube and the TED website:
So I picked up a copy and started reading it as my first of 25 books this year. Ironically, I read much of the first half while trying to fall asleep at night or upon waking up at 4am, too energetic to fall back asleep. Those may not be the best times to be reading about the apparent legion of harm that a lack of sleep can bring. Walker divides the book into four sections:
- What sleep is, how it differs (or is the same) among species and age groups, and what defines the different stages
- The multitude of benefits sleep brings and the perils of not getting enough sleep
- Why we dream and how it influences creativity and processing traumatic events
- How modern society has disrupted sleep and a few visions for the future to improve it
While the book has many interesting anecdotes (sleep homicide, anyone?), much of it can read a little like a very long review article that can get repetitive after reading about the seemingly hundredth medical condition that is aggravated by not getting enough sleep. These include, and are not limited to: learning and other forms of memory, attractiveness, food cravings and weight gain, cancer, Alzheimer’s disease, colds and the flu, heart attack, stroke, diabetes, depression, anxiety, auto accidents, PTSD, and medical malpractice. After a while, many of the effects seem to blend together (which is another side effect of not getting enough sleep).
However, since it reads somewhat like an academic review article, and Walker describes it as intending to serve as “a scientifically accurate intervention”, I found myself wanting there to be more citations. Some of the studies have references in the footnotes, but by rough estimate that is probably less than 10% of the number of studies alluded to. It is possible that the publishers didn’t want to increase the 360 pages [for my paperback copy] further, but they could have always made a “Supplementary References” section on the book’s website and added a page with a link at the end of the print copy.
In regards to those studies cited, this lengthy blog post, as well as numerous associated commentaries, have looked through the scientific claims and produced a list of inaccuracies that would make most Reviewer Number 3s seem kind. Interestingly, in addressing the commentary of the book being that of pop-science and may not need to stand up to the same level of academic rigor, the blog notes that the book has already been cited by over 100 academic papers, several of which have cited some of its false claims. From a scientific standpoint, this level of noted inaccuracies is worrisome to say the least.
Overall though, I think the book is worth the read to learn about many of the possible conditions and skills that sleep can improve. As someone who used to pride themselves on the ‘I’ll sleep when I’m dead’ mentality in undergrad, I’ve since changed to fully embrace it and get as much as I can. I know that my performance is woefully impaired when I have less sleep and for many people who are chronically sleep deprived, this book could be the little extra nudge they need to start forming some better habits. I’m particularly interested in how alcohol at night affects REM sleep and Walker’s proposed future ideas of using the Internet of Things to link household light brightness, color temperature, and thermostat controls to wearable sleep trackers to improve sleep. However, for anyone with hypochondriac tendencies, I would highly recommend caution and a high degree of skepticism when looking at the specifics of the presented data claims, particularly around fatal conditions like cancer. We could probably all use more, and better quality, sleep, but I don’t think the scientific evidence is strong enough to definitely backup many of Walker’s claims.