Author: Matthew Walker
I have a confession to make. As I was reading this book, I could not stop talking about it to my family and friends. I urged every single one of them to read it and extolled the virtues of 7 and half hours of sleep a day. I suddenly became conscious and protective of my sleep time and even turned down a few invitations for late night parties that would make me sacrifice my sleep.
I read a lot of self-improvement books, but have never before felt this convinced by an author. I quickly glanced at the reviews on Amazon and noted that I was not alone. Almost every one of the reviews started out with an over-the-top recommendation for the book. One reviewer nicely summed up this sentiment by saying “This book will drive you to become an evangelist for sleep".
A deep and refreshing sleep is a critical component of our brain's daily maintenance cycle. Just like you can drive a car without an oil change every six months, you can get by with less sleep. However, it will take its toll and you will be more susceptible to scores of ailments that afflict all human beings. Dr. Walker has found that a lack of sleep increases your likelihood of contracting chronic diseases like Hypertension, Diabetes, Cancer, Heart Attacks, Alzheimers, Obesity and Depression. He writes about the different phases of sleep like NREM, deep NREM and REM, and breaks down the specific benefits of each phase. The NREM portion of our sleep is the restorative phase for not only our brain, but our entire body. During the NREM phase our brain releases all kinds of chemicals and hormones that rejuvenate the many different organs in our body. In this phase, it also generates growth hormones that are critical to the buildup of muscles. So it should come as no surprise that a good night’s sleep is critical to the performance of all top athletes.
In contrast, REM sleep is critical to the recharging of our brain. This is the period when we dream. Contrary to our physical body, it is the time when the brain is highly active, with rapid eye movements. All the rest of the body’s musculature is cut off from the brain during this period, so you are unable to physically act out your dreams. During our REM sleep the brain processes everything that you have learned during the day. It filters out the unnecessary stuff and files away the pieces that you may need for the future. Hence it is critical for our learning and retaining knowledge. Dr. Walker highlights several studies that underscore the importance of sleep for memory retention and is very clear in his recommendation that you are better off taking the time to have a good night’s rest before an exam, than spending a few more hours cramming. Our brain also prunes and maintains synaptic connections during REM sleep and there is an argument to be made that many creative ideas originate in our brain during our dreams. Another benefit of REM sleep is that it helps us forget some of the distressing emotional fallout from our traumatic encounters, which is necessary for us to heal and move forward.
Dr. Walker notes that every animal species (even pre-vertebrates) sleeps, despite the fact that most of them have to live with the constant threat of predators. The fact that sleep has survived eons of evolution indicate that it must be a biological necessity. Read this book, but don’t do it at the cost of getting a full complement of required sleep.
