Matthew Walker's new book examines why we sleep and dreamMatthew Walker, author of the new book Why We Sleep, is on a mission. Elucidating the many benefits of sleep, he’s out to persuade us that the key to health, attainment, and longevity lies in 8 hours of shut-eye every night.

Use of the familiar 8-hour yardstick as a measure of sleep need may give insomnia sufferers pause. We’d be happy to sleep 8 hours a night . . . if only we could.

Don’t let Walker’s prescriptiveness stand in the way of reading his book. Its appeal rests on the author’s account of discoveries relating to the wonderful things sleep does for us—which should be of interest to us all.

A Sleep Scientist Writes for a Lay Audience

I’ve been following Walker, a professor of neuroscience and psychology at U.C. Berkeley and director of the Center for Human Sleep, for years. He’s done important research on the effects of sleep and sleep deprivation on learning, memory, and emotional memory processing.

With Why We Sleep: Unlocking the Power of Sleep and Dreams, Walker steps outside the world of academia to engage with the general public. That’s a point in his favor, in my book, because research scientists who endeavor to write for a lay audience don’t have much to gain from it personally. No kudos from colleagues, no burnishing of the CV.

Yet now could not be a better time for scientists like Walker to translate their research into terms we can all understand. And it quickly becomes clear that Walker is bent on doing this out of a passionate conviction that as members of a 24/7 culture, many of us are suffering from sleep deprivation.

Knitting Up “the Ravelled Sleave of Care”

For decades scientists have been searching for an answer to the question of why we sleep. It turns out there’s not just one but rather many reasons.

“We sleep for a rich litany of functions,” Walker writes, “an abundant constellation of nighttime benefits that service both our brains and our bodies.”

What are some of the functions sleep performs? It

  • improves our ability to learn, memorize, make logical decisions and choices
  • strips negative experiences of their emotional charge, improving our mood and sense of balance
  • enhances creativity
  • shores up the immune system
  • regulates appetite and gut health
  • lowers blood pressure and maintains heart health

Says Walker, with all the benefits sleep affords living organisms and how damaging the state of wakefulness can be, perhaps the real question is this: Why did life ever bother to wake up?

Diving Into the Research

Why We Sleep has four parts. In part 1 we learn about the basics of sleep. Parts 2 and 3 contain accounts of recent discoveries relating to the functions of sleep and dreams, which Walker presents together with personal anecdotes and easy-to-grasp analogies.

One discovery pertains to the question of why sleep deprivation makes us emotionally reactive and why a good night’s sleep sets us back on an even keel. Walker and others found the answer in the prefrontal cortex—the seat of rational thought that rests just above the eyeballs—and the amygdala, the emotion center deep in the brain. It could only be seen with the help of brain scanning technology.

“After a full night of sleep,” Walker writes, “the prefrontal cortex . . . was strongly coupled to the amygdala, regulating this deep emotional brain center with inhibitory control. . . . Without sleep, however, the strong coupling between these two brain regions is lost. We cannot rein in our atavistic impulses—too much emotional gas pedal (amygdala) and not enough regulatory brake (prefrontal cortex). Without the rational control given to us each night by sleep, we’re not on a neurological—and hence emotional—even keel.”

Caveat for People With Insomnia

Walker’s target audience is the multitude of healthy, normal sleepers who, out of necessity or by choice, do not alot 8 hours of the day to sleep. Insufficient sleep can have dire consequences: microsleeps while driving, often deadly; poor decision making; increased susceptibility to a host of health conditions and illnesses, including depression, stroke, dementia, cancer, diabetes, heart attacks. By dwelling on the alarming results of sleep deprivation studies, Walker means to wake us up to the dangers of “just getting by” on 5 or 6 hours a night.

But what if we’re willing to set aside 8 hours a day for sleep—and regularly do—but all we can sleep is 5 or 6? Lying in bed for 8 hours when we’re only sleeping 5 or 6 is precisely what insomnia sufferers should not do, because this only serves to perpetuate our insomnia.

Keep These Things in Mind

  1. The sleep deprivation literature Walker refers to throughout the book is based on studies of healthy, normal sleepers whose sleep need is presumably in the 7- to 8-hour range. On a steady diet of anything less, they experience sleep deprivation.
  2. The sleep needs of people who want to sleep more but can’t may be different from the needs of those who can sleep but do not sleep their fill.

While Walker’s book contains a short section on insomnia in part 4, Why We Sleep is not the go-to resource if you’re looking for help with insomnia. But it’s an excellent resource if you want to learn about sleep and the benefits it bestows.

Posted by Lois Maharg, The Savvy Insomniac

Lois Maharg has worked with language for many years. She taught ESL, coauthored two textbooks, and then became a reporter, writing about health, education, government, Latino affairs, and food. Her lifelong struggle with insomnia and interest in investigative reporting motivated her to write a book, The Savvy Insomniac: A Personal Journey through Science to Better Sleep. She now freelances as an editor and copy writer at On the Mark Editing.


  1. Hi Lois,
    I haven’t purchased Dr Walker’s book yet but will soon. I always find his work interesting, and like you said he is one of the more accessible with his research findings. He also declared that sleep is not one of the pillars of health, it is THE FOUNDATION for health. Powerful statement!




    1. Hi Michael,

      With all the functions sleep apparently performs for us (and who knew?!), I’d go along with Walker’s claim that sleep is the foundation for health (he makes that statement in Why We Sleep, too). He’s certainly someone to watch. Thank you for writing in!



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