New Sleep Book Is a Fascinating Read

Matthew 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.

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.

Get Rid of Unfounded Ideas About Sleep

People sometimes ask whether chronic insomnia is mainly a physiological or a psychological problem. Often it’s both.

Certain beliefs about sleep can interfere with getting a good night’s rest. A reality check can help you sort out truth from myth, which in turn may help you sleep.

Insomniacs will sleep better if they're rid of erroneous ideas about sleepPeople sometimes ask whether chronic insomnia is mainly a physiological or a psychological problem. Often it’s both.

High reactivity to stress—whether strictly biological or due to a combination of biological and environmental factors—may predispose you to insomnia. But there’s probably a psychological aspect to the problem if insomnia is a persistent feature of your life.

Certain beliefs about sleep can interfere with getting a good night’s rest. A reality check can help you sort out truth from myth, which in turn may help you sleep.

I need 8 hours of sleep a night to function well.

If the National Sleep Foundation (NSF) recommends 7 to 9 hours of sleep for young and middle-aged adults and 7 to 8 hours for older adults, then it follows that 8 hours of shut-eye is the gold standard, right?

Not necessarily.

Sleep experts still haven’t figured out how to measure an individual’s sleep need. Prescriptions like the NSF’s are based on huge data sets containing information about sleep duration and longevity. The data, when graphed, fall into a U-shaped curve, with people whose sleep duration falls in the middle of the curve outliving those at both ends (i.e., the really short and really long sleepers).

Authors of recent analyses have concluded that it’s the 7-hour, and not the 8-hour, sleepers who live the longest. And in an early study involving data from over a million patients, people who slept 6.5–7.4 hours outlived the rest.

Keep in mind, too, that data on sleep duration in these big, retrospective analyses are usually based on subjective estimates, not on objective measures of sleep time. Finally, the recommendations on sleep duration set forth by the NSF panel are offered with this caveat: “some individuals might sleep longer or shorter than the recommended times with no adverse effects.”

You may think you need 8 hours of sleep based on personal experience. Especially if you’re not sleeping well, an 8-hour night can feel heavenly. But to assume you need 8 hours of sleep every night is a mistake.

There’s an average amount of sleep each of us needs for peak functioning. Normal sleepers, whose sleep periods are fairly regular, can estimate their sleep need pretty easily based on the time they drop off and wake up.

But insomniacs’ sleep is often erratic—2 or 3 bad nights followed by a good night—with the pattern repeating again and again. Sleep need on a given night is based on several factors: how long you’ve been awake, what you did during the day, and prior sleep. You may need 8 hours of sleep following several stressful days and short nights. But your average sleep need may be more like 6 or 6.5 hours a night.

I’m worried insomnia is going to do serious damage to my health.

Chronic insomnia is a risk factor for several nasty ailments: cardiovascular disease, depression, and fibromyalgia, to name a few. But saying something is a “risk factor” for something else does not imply causality. It simply indicates a correlation between one thing and another.

For example, if chronic insomnia is a risk factor for whiplash (it is), insomnia makes you more vulnerable to whiplash but does not indicate that you will develop whiplash. Even if you have chronic insomnia, the statistical probability of your developing whiplash is still relatively low.

Why scare the sleepless with talk of health problems we may or may not develop? Well, for years insomnia was dismissed as a trivial complaint without consequence. The fact that it has now been shown to have a relationship with other serious ailments makes it clear that insomnia is worthy of attention and treatment, and that insomnia research is worthy of funding. This is actually a boon for us.

All it takes is one bad night and my sleep is toast for the rest of the week.

If you’ve got chronic insomnia, it may be that sleeping poorly triggers anxiety about sleep, which in turn may make sleep more difficult the following night. Anxiety and worry are rarely compatible with sleep.

But as mentioned before, there’s an average amount of sleep each of us needs to function. You may not actually be aware of the amount you need, but your body IS aware of that amount. In fact, there’s a mechanism—the sleep homeostat—with a set point that keeps track of how much you sleep every night.

A bad night is going to register with the sleep homeostat as an inadequate amount of sleep. The result will be a greater build-up of sleep pressure the following night. Two bad nights will result in even greater pressure to sleep on the third night . . . and so on.

So while negative thoughts about sleep can prolong sleeplessness, an array of forces inside your body are actually working to promote sleep. They always win out in the end.

What ideas about sleep cause you the most anxiety?

Are We Really Sleep Deprived?

People with insomnia typically worry about not getting enough sleep. It’s easy to understand why. The media are are full of stories warning of the perils of insufficient sleep: obesity, diabetes, dementia, cardiovascular disease.

But a study of sleep in 3 traditional societies published in October suggests that humans may need less sleep than we think we do—which should give insomniacs food for thought.

Insomniacs may not need as much sleep as they thinkPeople with insomnia typically worry about not getting enough sleep. It’s easy to understand why. The media are full of stories warning of the perils of insufficient sleep: obesity, diabetes, dementia, cardiovascular disease.

The Centers for Disease Control and Prevention for several years declared insufficient sleep to be a public health epidemic (last year they revised the language to “public health problem”). And according to an estimate set forth in Sleepless in America, a documentary released on the National Geographic Channel in December 2014, Americans sleep considerably less than we did 150 years ago.

But a study of sleep in 3 traditional societies published in October suggests that humans may need less sleep than we think we do—which should give insomniacs food for thought.

Making Inferences About Sleep in Times Past

How did people sleep millennia ago? Has electric lighting really had as negative an impact on sleep as sleep experts claim it has?

The scientists and anthropologists who conducted this study couldn’t travel back in time to assess the sleep of our ancestors. So they did the next best thing: study the sleep of 3 hunter–gatherer and hunter–horticultural societies in existence today. These traditional peoples, who live without electricity or any modern technology, live in equatorial regions of Tanzania, Namibia, and Bolivia.

What They Found Out

The investigators used wristwatch-type devices to measure sleep duration and light exposure for 94 adults over a total of 1,165 days. Following are some interesting findings:

  • People in these traditional cultures slept 5.7 to 7.1 hours a night—less than average sleepers in modern industrialized societies like the United States. Yet extensive research has found that although their daily energy expenditure is about equal to that of most Americans, they’re healthier and more physically fit than we are.
  • People did not go to sleep at sunset, as has been assumed about people before the advent of artificial lighting. On average, they went to sleep 3.3 hours after sunset, keeping vigil in the dark except for a small fire and moonlight. So electric lighting is probably not the only reason we like to stay up to watch the late show. Perhaps Thomas Edison did not have as big an impact on sleep as we think.
  • People got their sleep in a single sleep episode uninterrupted by long periods of wakefulness. Daytime naps were the exception rather than the rule. This challenges the idea that early humans had two separate sleep episodes interrupted by a wakeful period in the middle of the night, or that they routinely took daytime siestas.

Relevance to Insomnia

Many people with insomnia say they need 8 hours of sleep a night, and maybe some of us do. Yet although this study by itself is not evidence that we need any less, if it convinced us to revise our beliefs about sleep need downwards, it wouldn’t be a bad thing.

Sleep therapists say that one thing that happens to many insomniacs as their sleep improves is that they let go of the idea that 8 is the magic number. Sleep quality may matter more than the number of hours we get.

Why Such Alarmist Messages?

Sleep isn’t always seen as important—yet it is a pillar of health alongside diet and exercise. But the alarmist tone of some of the messages we hear about not getting enough sleep (“a public health epidemic”), and the fact that healthy sleep is almost always defined as a certain number of hours, is worrisome to people with insomnia and others whose nightly share of shut-eye falls short. How helpful are such messages really?

The cynic in me says the pharmaceutical companies and medical device makers are behind this campaign to insist that we aren’t getting the sleep we need. Because who stands to gain more from convincing us that we’re sleep deprived than the folks who sell Ambien and CPAP machines?

But Americans toward the end of the 19th century were also worried about their sleep. After the Civil War, many were moving off the farm and into the city, where life was more stimulating, and both faster paced and more sedentary, than on the farm. A widely held view was that civilization was evolving faster than the human organism could keep pace with, and good sleep was falling by the wayside.

Are we living in a similar climate today? Do the dire warnings about insufficient sleep fit in with general concerns about the pace of our 24/7 lives, and do they likewise reflect anxiety about social changes and/or fear that we can’t keep up?

I’d like to know what you think.