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 Causation Walker'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 Style According 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 Sleep The 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. Dreams Some 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 Rhythms Throughout 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 Flaws Walker'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? Conclusion Overall, 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.

I became interested in this book because I wanted to learn how to sleep better. Did it answer my questions? Most of them, I would say. The book is divided into four parts. Readers can choose to read each part independently and not in a specific order. That’s exactly how I read it—out of order and focusing on topics that interested me most—such as jetlag, sleeping pills, dreams, and healthy sleep. Part 1: This Thing Called Sleep What I liked most about this book is how it dispels myths about sleep. Let's start with sleeping pills. Most of the sleep aids on the market are based on Melatonin. Essentially, melatonin helps regulate when sleep occurs, but it doesn’t put you to sleep. Using melatonin for jet lag may not guarantee sleep, but it significantly improves the chances by providing the right timing signal. Another common misconception is that drinking alcohol before bed helps us sleep better. It actually has the opposite effect. Part 2: Why Should You Sleep I used to hear stories about great people who only slept a few hours a night and got more done than most folks. However, even people like Bill Gates now say that getting eight hours of sleep is important. Sleep deprivation can lead to serious problems. People who don’t get enough sleep tend to lose productivity, and their health can suffer as their immune system weakens. A more dangerous situation is when sleep deprivation affects our ability to drive safely. Part 3: How and Why We Dream I always try to interpret my dreams, especially scary ones, to understand what they mean. The author examined dreams from a scientific perspective. It's almost like fortune telling when we try to decode a dream. However, with scientific data, they showed that people become more creative and better at solving difficult problems during dreams. He shared examples from well-known individuals like Thomas Edison and Paul McCartney—very interesting findings. I think I need to dream more so I can boost my creativity! Part 4: From Sleeping Pills to Society-Transformed This part was my favorite because it answered many of my questions. With modern society, we face increasing distractions every day. Aside from computers at work and home, we have numerous electronic devices like iPads, cell phones, and smartwatches. Spending too much time on these devices before bed isn’t healthy. It was eye-opening to learn that factors such as the blue light from LED screens, room temperature, and lighting can all impact our sleep. The author clearly states at the beginning that his book isn’t meant to be a self-help guide, nor is it targeted at treating sleep disorders. However, he includes an appendix titled "Twelve Tips for Healthy Sleep." This book is grounded in data and facts. I learned a lot from reading it and thoroughly enjoyed the experience. For those who aren’t interested in all the experimental details, you can still gain valuable insights from it.

Why We Sleep is an overview of the author's research into the purpose of sleep as well as the consequences of a lack of it. It discusses a lot of issues and the author gives his views on the evolutionary benefits and distinctiveness of humans, so it really is quite comprehensive. Most people today, myself included, just are somehow unable to get a healthy amount of uninterrupted sleep and the author does a good job of explaining the consequences of that to the individual through multiple cognitive lenses. He also considers the consequence to the country as a whole through its loss of productive capacity due to overworking. The book is split into four, largely independent sections. The author begins by discussing how sleep occurs, including some of the neuroscience and the chemical cycles associated with our sleep schedule. The reader learns about the marginal differences between certain physiological cycles and the 24 hour day. In addition the causes of jetlag are explored as well as the required adjustment for changing time zones. The author discusses a bunch of experiments done where we were able to learn about our cicadian cycles and some of the differences in sleep requirements any cycle times by age. The author also highlights his novel view on how REM sleep was associated with human ability to light a fire which allowed them to sleep on the ground rather than be in an unstable position in a tree and this evolutionary advancement was essential for modern development. Perhaps, probably not, but the author truly is impassioned about the subject with strong views. The author then gets into why we need sleep and discusses with abundant experimental evidence, the benefits of sleep to cognitive abilities and the necessity of it for healthy living. Some remarkable pathologies are discussed, for example there was an individual who lost the ability to go to sleep and their body slowly lost its ability to function and the disease proved quickly fatal. The author highlights that the Guinness Book of World Records struck the longest period without sleep as a category due to its terrible health consequences and the author spends time on the consequences of lack of sleep to driving abilities highlighting the large number of fatalities that follow. The author also discusses the benefits of sleep to overall body health and gives substantial experimental evidence to the regenerative benefits of sleep to natural ailments. The author does highlight that sleep will not just cure cancer but simultaneously implicitly argues that it might. So the author, with evidence, strongly argues that sleep has the ability to help one regenerate far more than the general scientific community currently advocates. The author gets into dreaming and how sleep breaks up. He discusses how each form of sleep is required and they have different functional benefits. Furthermore the body needs for NREM and REM sleep differ in immediate priority but not in absolute priority and these results are discussed with experimental evidence for how the body catches up on sleep after being deprived. The author discusses multiple memory experiments that depend on prior sleep conditions and highlights the substantially better performance statistics of students who have had enough sleep prior to trying to learn facts. The author then discusses the consequences of sleeping pills, which are considered significant and detrimental. The author also clarifies the difference between sedation and sleep and makes it very clear that sedation is not sleep and does not serve as a remedy and can be counterproductive. Alcohol's detrimental effects are considered by their impact on sleep for example. The author goes through several common sleeping tablets and makes it clear he does not believe any are substitutes and argues they can become dependencies that create major long term problems. The author then discusses how much better the world could be if we all paid more attention to sleep and how overall productivity of the society could be enhanced. This sort of analysis is interesting but also in need of being the most skeptical of in terms of being a realistic analysis. Why We Sleep is informative and entertaining. It is exaggerated at times and so aspects of the credibility of the book can be highlighted. The author argues multiple times how even one night of sub optimal sleep has distinct impacts on ability and how an all nighter can be catastrophic, only to bring up an example in which an individual goes without sleep for multiple days to then sleep and make a major scientific discovery. The point of the example was to display the benefits of sleep but it erodes the earlier argument that any lack of sleep puts the individual at a massive handicap. Thus the author argues too forcefully for the unrealistic, that we need 8 hours a day without exception, while highlighting that he himself often cant sleep properly once a week. Despite the at times marginally inconsistent tone, the book is a good reminder of the importance of sleep, a good reference for the scientific benefits of sleep and important tutorial on the health requirements for sleep.

This is a fascinating book. Sleep is one of the least-understood aspects of life, even though it constitutes one-third of our human experience. Or it should. The ingrained attitude for many of us is that sleep is a necessary evil, something that interferes with our ability to work and produce. On the contrary, the absence of sleep makes us less productive, less happy and healthy and more prone to disease. I have always been fascinated by the subject but disappointed by the absence of research on that subject. Professor Walker’s book digests the available research and presents it in a lucid manner that will be accessible to all curious readers. If I have a single criticism it is the relative paucity of material on dreams and dreaming, but that is a vastly complex subject that is not as susceptible to analysis as, e.g., the effects of light on the release of Melatonin and the ways in which we could physically and temporally structure our environment to correspond with our bodies’ needs. One of the most important themes of the book is the fact that our lives are structured in such a way as to encourage ill-health, medical mistakes, automobile accidents and poor learning. Early school start times, e.g., deny children and teenagers the important, early-morning REM sleep that their brains require. The sleep-deprived schedule for medical residents was fashioned by a cocaine addict who was himself sleep-deprived. The absence of sleep and interruption of sleep have statistically-demonstrable, negative effects on our lives. As they say on ‘Shark Tank’ when ridiculing infomercials: “Stop the Madness.” The bottom line is that we need regular, appropriate sleep to maintain a healthy immune system and to heal our spirits. While this is solid and informative, the result of serious and significant research, it is not counter-intuitive. Popular sayings across the world and insights from such acute observers of the human condition as Shakespeare anticipate many of the book’s conclusions, but as I stated earlier, while these principles may be reinforced by common sense they often run directly counter to our current behaviors. Alcohol, for example, does not contribute to effective sleep and caffeine can have longer-term effects than we believe. LED lighting is superb for some purposes, disruptive for others. The book includes a succinct two-page list of tips for healthy sleep as well as a commonsensical set of public policy recommendations. This is an important book as well as a fascinating one. Highly recommended.

As humans, why must we sleep roughly a third of our lives? What is the function of our dreams? If these questions intrigue you, consider reading Matthew Walker's excellent book Why We Sleep. The book delves into all aspects of sleep from a person who is passionate about the subject. It starts by discussing the different portions of our sleep, including REM sleep, when our eyelids flicker while the rest of our body is paralyzed, and the very deep NREM sleep with its associated rhythmic brain waves. The book talks about what controls the circadian rhythms in our sleep, from the suprachiasmatic nucleus, which samples the light near our eyes, to the different chemicals, melatonin and adenosine, that are part of these daily sleep rhythms. Interestingly, much of what we know about sleep was discovered by explorers, who subjected themselves to the tremendous darkness deep in Mammoth Cave and performed sleep experiments. The book goes into great detail about exactly what happens when we go into deep NREM and REM sleep. In particular, memories are initially formed in the hippocampus, which acts as a short-term repository; in REM sleep, many connections are made, and the memories are spread throughout the cortex, which can be seen in fMRI imaging. The book presents a nice analogy of how our mental picture is like a sculpture, and NREM sleep takes off bits of it, whereas REM sleep refines and solidifies the features. The balance between these two types of sleep changes throughout our life as we have different needs for creating connections and removing extraneous memories. Even the nightly balance between the two changes, with more REM sleep later on. The book also discusses the bad things that can happen to us if we don't sleep enough, from obvious consequences of getting into car accidents or forgetting things, to diseases, such as cancer, heart disease, and obesity. The book finishes with a lengthy discussion of what we can do if we can't sleep and how medicines for insomnia work. It presents some simple rules for getting a good night's sleep, such as avoiding alcohol and caffeine and keeping a regular bedtime. One suggestion I found interesting was staying away from blue LED light at night. Although its discovery in the '90s resulted in a Nobel Prize, blue LED light has been bathing people in sunlight-like light more and more in the evenings from our many screens, impacting sleep. Overall, I felt this was a great read from a person very committed to the subject.

Our understanding of sleep has made large steps. It is only in the past two decades that we have a much better understanding of its function and, importantly, on the serious health repercussions of sleep deprivation, the overarching theme of the book. At its extreme it’s fatal (fatal familial insomnia, a very rare genetic mutation) but even a mild degree of deprivation e.g. 6h vs. 8h have a long series of detrimental effects: higher blood pressure and higher heart rate, higher level of stress hormone cortisol, lower degree of growth hormone, increased probability of weight gain (sleep is intensely metabolically active), drop in testosterone (less focus, less strength, and lower bone density) and, icing on the cake, more damages to telomeres (protective caps of genes). In certain experiments 10 consecutive nights with 6h of sleep are equivalent to 24h without sleep, which, as far as concentration is concerned is equivalent to being legally drunk. For healthy sleep, humans, as well as most other species, need a correct balance between non-REM (NREM) sleep, very important for transferring short term memories into long term and ‘cleaning up’ for irrelevant memories (e.g. where we parked the car the previous day) and REM sleep, very important for emotional processing as well as problem solving and creativity (deep and unconventional connections are formed). While these phases cycle through the night approximately every 90 minutes, their relative periods are not constant. In particular, the REM portion of the cycle is far more prominent towards the end of the 8 hours. Cutting the night short might deprive us of an important dose of REM sleep. The author corroborates findings with plenty of scientific experiments and their findings and touches on many aspects of the science of sleep and related illnesses like clinical insomnia, somnambulism, sleeping in older age, and narcolepsy. Especially the former is important to guide the reader between ‘bad sleep’, quite common, and clinical insomnia. Coffee, for example, blocks adenosine receptors making us less aware of our need to sleep. Alcohol suppresses REM. Lastly, sleeping pills provide more ‘sleep’ but at the expense of REM sleep. He concludes the book with 12 advises for obtaining sound sleep. If one can only achieve one then it is suggested to go to sleep and wake up at the same time every day, weekends included. The book is very readable, rich in details and very informative. Understanding why we sleep and having a better sense of the dynamics of sleep is fascinating, personally, but can also help improving sleep, thus health, in general. Slightly repetitive at times but overwhelmingly a great read. Given the importance of the topic and all the light shed on the obscure nature of sleep, I give it full marks, without hesitation!

I am blown away at how much I am learning with this book! Thank you, Dr. Walker. It has opened my eyes to my many wrong approaches to sleep, soI started implementing Dr Walker's recommendations about a month ago. I am definitely seeing results already, although I am a work in progress. I assume I will always be, from now on. Healthy sleep has become a vital part of my daily health, mind and fitness routines. It is a must. I honestly believe the knowledge in this book should be available -in a simplified format- to our children in school, as their sleep patterns change as they age and enter puberty and so forth. The impact of sleep, dreaming and deep sleep in our emotional health is way too important to dismiss or not even acknowledge. These are proven facts backed up by hundreds of sleep studies. It is such an interesting concept, and I cannot believe I am learning this now, at 60 years of age.

Excellent book to read on the importance of getting enough sleep. Turning off all stimulation and preparing yourself and or your child for a good nights sleep. Amazing at all the health benefits and what happens to your body and brain when sleep deprived.