Why We Sleep: Unlocking the Power of Sleep and Dreams

"I was once fond of saying, 'Sleep is the third pillar of good health, alongside diet and exercise.' I have changed my tune. Sleep is more than a pillar; it is the foundation on which the other two health bastions sit. Take away the bedrock of sleep, or weaken it just a little, and careful eating or physical exercise become less than effective, as we shall see."― from “Why We Sleep: Unlocking the Power of Sleep and Dreams”Matthew Walker's "Why We Sleep" is one of the two most important books I have read in my life1. Having done a little stock trading along with having survived several tech industry "death marches," things which are quite antithetical to good sleep, I had little idea just how destructive to your health lack of sleep is. A few years back, however, I began to hear that lack of sleep was correlated with diseases such as Alzheimer's, but this did not strike me as convincing since correlation is not causation. Indeed, a little later, I heard about this book at work but was somewhat ambivalent. It's just going to tell me that doctors think sleep is essential but are vague as to why were my thoughts.Luckily I noticed an episode of Sam Harris's podcast "Making Sense" in which he interviewed Walker. Since Sam Harris is a figure whose judgment I highly respect, and I know he is very discerning about whom he invites on as guests, I decided there was probably more of value to say about sleep than I initially thought.Correlation and CausationWalker's book makes a compelling case that sleep is the bedrock of good health. He convincingly demonstrates that lack of good sleep can lead to downward spirals in health with the development of health conditions that make it hard to sleep, leading to more serious health conditions due to lack of sleep, making it even harder to sleep… and so on into a vicious cycle. Walker is careful to lay out in detail when the causal mechanisms are well understood, as in the case of Alzheimer's and cancer, and when lack of sleep is currently a suspect, although the exact causal mechanism has yet to be established. By the end of the book, I realized, however, that sleep is so foundational that even a mere correlation to some bad health condition is enough to make lack of good sleep a prime suspect worth considering as a cause.Organization and StyleAccording to Walker, "Why We Sleep" is organized so that later chapters can be read without a strict need to read earlier ones first. Thus, if you use sleeping pills and want to know why you should not, he says it is okay to and, indeed, encourages you to jump to that section right away. That being said, I found the writing style so engaging (with a few minor instances of excessive detail) and the content so important that I read it straight through. Having read it this way, my sense was that the book frontloads its most important content: It explains in detail, with specifics such as the chemicals involved, why you feel more tired at certain parts of the day than others. To give you the motivation to get good sleep, the deleterious effects of lack of sleep also come near the beginning of the book.The Enormous and Far-Ranging Effects of Poor SleepThe effects of lack of sleep go beyond just affecting your physical health, however, and Walker shows just how destructive lack of sleep will be on your ability to learn new things. One of the most remarkable findings is that you need to get good sleep after learning new information. You cannot even get a single night of suboptimal sleep the first night, or some information will be lost permanently.Conversely, if you get that first night of good sleep after learning something new, sleep on subsequent nights will continue to solidify what you have learned: all while you sleep! This is just one case where Walker details how, unfortunately, missed sleep cannot be well compensated for by more sleep later: Permanent losses are involved.DreamsSome of the most fascinating information in the book is on the role of dreams. Here we learn of their therapeutic qualities, including some of the underlying biochemistry involved. Discoveries here have led to a better understanding of PTSD, including better treatment methods. Walker also describes how dreams foster creativity by establishing connections between distantly related pieces of information stored in the brain. Here Walker includes a particularly fascinating anecdote of how Edison enhanced his creativity by waking himself from naps and immediately recording his thoughts.Empathy For Different Circadian RhythmsThroughout the book, Walker emphasizes how what we have learned about sleep has implications for how we should view people who may not have what seem like "normal" sleep patterns more empathetically. In particular, he emphasizes that teenagers want to get up and go to bed later, not due to laziness but because they run on a different circadian rhythm. It is something that is biologically hardwired into them. A consequence is that forcing school start times incompatible with this has devastating effects on how well they learn compared to well they could. Similar facts are true of people who are naturally "night owls" and run on different circadian rhythms than the rest of us.Minor FlawsWalker's book has only a few minor flaws:1. Although he provides an excellent explanation of why most sleeping pills should be avoided, he does not mention whether this includes melatonin.2. His discussion of the nationwide dollar impacts of poor sleep could be better presented. The unfortunate truth is that given the numbers we have heard spent on wars and, especially, financial bailouts and stimulus, rattling off numbers that are “merely” in the hundreds of millions or even low billions hits us in a place we are now numb.3. Although Walker's discussion of creativity in the dream state and the state when just waking from dreams is a fascinating part of the book, I would have liked to see some discussion of how objectively accurate intuitions are during these moments. Anecdotally, I used to joke that my best ideas came to me during this time or not at all. Sometimes, however, the thoughts just turned out to be overconfident upon more profound reflection. Is that true for just me, or is it true for people, generally speaking?ConclusionOverall, Walker's "Why We Sleep" is a must-read for anyone who sleeps: in other words, everyone. This book will not only absolve you of any guilt associated with prioritizing sleep, but it will also arm you with the knowledge to make the best choices for your physical and mental health. Walker guides you through the critical benefits of sleep, from its integral role in memory and creativity to its power to process and put to rest the day's experiences: especially the more troubling ones.While the damaging effects of lack of sleep seem exponential, Walker argues that some of the most significant benefits come in the final two hours. Thus getting eight full hours of sleep is crucial. After reading this book, you will not want to miss a full night's sleep again.To help you achieve a full night's sleep regularly, Walker provides 12 concrete steps in an appendix. Some of these suggestions are initially counterintuitive. For example, Walker maintains that a cooler room temperature of around 65F is best for optimal sleep. Already, I've been putting this and his other advice to the test, and the results seem promising.

Clear and accessible writing supported by extensive research, with a sprinkling of tongue in cheek humor, this book needs to be read, attended to, and the information disseminated and applied throughout all areas of our cultures. Flexible and overlapping work hours, yes! Later school start times, yes! Better sleep for better health and life, yes! Learning to appreciate the myriad effects of sleep, yes! 💤

The science presented in this book is very real and very relevant, sometimes esoteric but mostly boiled down to practical, applicable advice and insight about sleep. Many of the scientific findings cited in the book have links or bibliographic information back to white papers that you can look up, and I appreciated this level of diligence and legitimacy.Sometimes, the message -- that we as a society treat sleep too lightly -- reads as a call-to-action, and I appreciated the urgency. It also sometimes felt bombastic, histrionic, with language such as "platinum-grade nocturnal service" and "brain feasting on this emotional recalibration" when referring to sleep's functions. As such, the book wasn't easy to read, and I didn't breeze through it since the diction was often too high and rich with exaggeration.But the meat of the book -- descriptions of scientific studies and their relevance to sleep -- translates well to advice we can apply to sleep, including treatment plans for insomnia like CBT-I (cognitive behavioral therapy for insomnia), ways of educating those around us, ideas for sleep technology, and in-depth studies of why the brain regulates mood/memory/pain better with consistent sleep. I believed in sleep heading into the book, but I still learned a lot about the various parts of the brain, and the reasons each part benefits from specific portions of sleep, deep REM (Rapid Eye Movement) sleep or NREM sleep. The author explained terminology and backed up his claims with tests and citations, some on humans, some on rats.I could do without all the societal hand-wringing and public policy reform, but I do feel like the book elevates my valuation of how important sleep is, and how we can achieve better sleep through practical methods like temperature regulation, analog reading, and encouraging mind games. Dr. Walker addresses sleep debt, short vs. long-term memory, caffeine, adenosine, and melatonin early in the book, setting the stage for more advice-focused chapters later on. He never properly defines a "sleep spindle," but whatever it is, the book provides a good argument and evidence for improving the quality and number of our sleep spindles through time, consistency, and the proper respect & environment for quality sleep.