Book Notes #6: “Why We Sleep” (By Matthew Walker)

by | Jun 20, 2022

This book is one of the best I’ve read in my life. That’s not hyperbole. A book that gets you not only to think but take action in your life can be truly special. But many books can do just that. However, sleep and the human need for it is so fundamental and recurring, that modest reforms in your sleep regimen can have untold benefits for you throughout life.

I’m working on a sleep meditation album, and I wanted to get wise on why we sleep — and how to enhance the quality of it. A friend recommended this book, and I’m so glad that he did.

Why We Sleep
By Matthew Walker

Here are 7 takeaways:

  • 12 ways to enhance your sleep
    Let’s start with the essential recommendations. Walker has a handy appendix that lists the ways to enhance your sleep:1. Stick to a sleep schedule. Go to bed & wake up at the same time every day. Even if that means setting an alarm to goto bed.


    2. Exercise but not 2 or 3 hours before you goto bed.

    3. Stay clear of caffeine and nicotine – especially in the afternoons

    4. Avoid alcohol.

    5. Don’t have a big meal or many beverages before sleeping.

    6. Avoid medicines that prevent sleep.

    7. Don’t nap after 3 pm

    8. Take it easy before bed. Dim the lights. Listen to calming music.

    9. Draw a hot bath/shower before bed.

    10. Keep your bedroom dark and with no gadgets.

    11. Low sunlight exposure.

    12. Don’t lie in bed awake.

    Walker goes into detail on each of these points. The appendix alone is worth buying the book. Many of these suggestions are passive. By default, you will eat dinner. But you have to actively choose to have a big meal. There are a lot of things on this list you may be able to easily do.

  • Boost your health
    When you’re sleeping, you’re healing. The body engages in complex processes to ward off disease, infection, bacteria. Walker jokes that if there were a medicine that was found to give the same benefits of sleep, people would pay a fortune. Walker presents compelling scientific research with impressive conclusions.


    Routinely sleeping less that six hours a night weakens your immune system, substantially increasing your risk of certain forms of cancer. Insufficient sleep appears to be a key lifestyle factor linked to your risk of developing Alzheimer’s disease…the shorter you sleep, the shorter your life span.

  • Sleep as medicine
    It follows that if sleep is so good for you, we should be trying to enhance it. Walker says that he lobbies doctors to prescribe and suggest more sleep for patience (instead of sleeping pills, unless there is a medical reason for them). I used to think of sleep as a necessary evil. But now I see it as an essential part of healing and enhancing my wakeful time here on earth. Walker refers to sleep as a “Swiss Army knife of health and wellness.”


    Within the brain, sleep enriches a diversity of functions, including our ability to learn, memorize, and make logical decisions and choices. Benevolently servicing our psychological health, sleep recalibrates our emotional brain circuits, allowing us to navigate next-day social and psychological challenges with cool-headed composure.

  • Danger: Too Little Sleep
    There’s a plethora of dangers of too little sleep. Workplace accidents, for example, occur at higher rates. For those in the medical profession, impaired sleep can have life or death consequences on patients. Drowsy driving is a severe threat to all our well being. When someone is asleep at the wheel, there is no reaction time of the driver. It’s like there’s a multi-ton missile with nobody operating it. And very few public health campaigns target drowsy driving. How many drinking-under-the-influence ads have you seen? How about drowsy driving? We need to do something about this.


  • The beauty of dreaming
    Walker spends a chapter examining the evolutionary origins of sleep and how animals also sleep. This is no doubt fascinating.But what I found most incredible were his passages on dreaming. There must be some evolutionary logic to why we dream. When we dream, the brain paralyzes our motor functions so we can’t act out our dreams. What goes on in our mind are theatrical fireworks that can linger with us.


    Dreaming provides a unique suite of benefits to all species fortunate enough to experience it, humans included. Among these gifts are a consoling neurochemical bath that mollifies painful memories and a virtual reality space in which the brain melds past and present knowledge, inspiring creativity.

    Dreaming is a form of therapy and takes the sting out of certain experiences.

    REM-sleep dreaming offers a form of overnight therapy. That is, REM-sleep dreaming takes the painful sting out of difficult, even traumatic, emotional episodes you have experienced during the day, offering emotional resolution when you awake the next morning.

  • Circadian Rhythm and Sleep Pressure
    There are two correlated forces that govern our sleep: (1) circadian rhythm and (2) sleep pressure. The circadian rhythm goes up and down during the day and serves as a “biological pacemaker” that runs for approximately one day.There are two chronotypes – morning or evening people. And this is usually an inherited trait. I’m a night owl.Adenosine is a chemical in the brain known as sleep pressure. This builds over the day, and it makes you feel sleep when there is an abundance of it. Think of this as a sleep barometer.


  • The stages of sleep
    Think of our conscious selves in three parts (1) awake, (2) NREM sleep, (3) REM sleep. Walker contends that these phases can be thought of as (1) reception – experiencing the world; (2) reflection – storing new skills, (3) integration (interconnecting the world). The brain scans and science backs up these descriptions. Humans evolved to be biphasic sleepers, which means sleeping twice a day (once at night, and a nap during the afternoon).As we age, the quality and even purpose of our sleep changes. As babies, new neural pathways form while we sleep, for example. REM (dream) sleep dominates early life. Sleep is critical to memory and learning. Naps can also help boost memory and performance.


    The more sleep spindles an individual obtained during the nap, the greater the restoration of their learning when they woke up…the more sleep spindles an individual has at night, the greater the restoration of overnight learning ability come the next morning….In doing so, sleep had helped future-proof those memories.

    As a musician, I appreciated Walker’s examination of how sleep can enhance motor skills.

    However, fitting with the pianist’s original description, those who were tested after the very same time delay of twelve hours, but that spanned a night of sleep, showed a striking 20 percent jump in performance speed and a near 35 percent improvement in accuracy. Practice does not make perfect. It is practice, followed by a night of sleep, that leads to perfection..


    There is also ample commentary on the negative consequences of too little sleep. As well as how to think about insomnia, apnea, and more ailments.

    Walker ends the book on a prescriptive note looking at how societies can function better with more sleep. For example, schools should start later so that students can sleep longer. Work schedules should be optimized so that people can get a full 8 hours of sleep every night.

    Must read!



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