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?

Your Sleep Need? Figure It Out Yourself

You’ve heard the advice to get 8 hours of sleep a night? Now they’re saying that 7 hours is the optimal amount of sleep–which may not be very cheering for most people with insomnia. Still our nights do not measure up.

If you have persistent insomnia, and if you fall short of the recommended 7 or 8 hours, it’s natural to wonder if you’re getting enough sleep. Here’s how to get a good sense of how much sleep you really need.

calculate your sleep need by keeping track of the hours you sleep on vacationYou’ve heard the advice to get 8 hours of sleep a night? Now they’re saying that 7 hours is the optimal amount of sleep–which may not be very cheering for most people with insomnia. Still our nights do not measure up.

As if that weren’t bad enough, the web is glutted with articles showing that short sleepers are vulnerable to a host of ailments: depression, heart disease, obesity, diabetes, dementia. Yikes! It’s a wonder any of us live past 65.

If you have persistent insomnia, and if you fall short of the recommended 7 or 8 hours, it’s natural to wonder if you’re getting enough sleep.

How Much Sleep Is Enough?

Sleep need—or sleep ability—varies a lot from one person to the next. Some people feel refreshed after 5 hours while others need 9. In normal sleepers, the duration of sleep is fairly consistent from one night to the next, so it’s easy to make inferences about sleep need. A person who under favorable conditions normally falls asleep at 11 and wakes up at 6 needs an average of 7 hours’ sleep a night.

But the sleep of people with insomnia is much more variable. Insomniacs are 60 percent more likely than good sleepers to sleep poorly on any given night. After a slew of bad nights, it feels heavenly to pop off a solid 8 hours. You wake up feeling rested and ready for the day—and this might lead you to infer that you need 8 hours a night to function at your peak.

But it’s a mistake to assume that the sleep you get on a night of recovery sleep is equivalent to the amount of sleep you need every night. It’s also wrong to assume that the 4 hours you more often get will suffice. The truth lies somewhere in between.

Track Your Sleep over Time

To find the amount of sleep you need for optimal functioning, keep track of the hours you sleep for a week or two and then take the average of that. This is probably closer to your daily sleep need.

But . . . this figure may be off the mark for people with persistent insomnia. Stress can interfere with sleep and make it hard to get an accurate read on sleep need. You may be slightly but chronically low in the tank.

A Better Way to Calculate Sleep Need

Eve Van Cauter, director of the Sleep, Metabolism and Health Center at the University of Chicago, suggested a better way to figure out sleep need or capacity in last week’s USA Today. Here it is:

Wait until you’re on vacation and free of the stressors connected to the daily grind. Once you’re away, go to bed at your usual time but do not set an alarm clock. The first few days you may sleep longer than normal to make up for the sleep debt you’ve accumulated at home.

Then, once your sleep stabilizes, start keeping track of how long you sleep. This, plus or minus 15 minutes, Van Cauter says, is as good a way as there is to get a handle on your daily sleep need.

A Tip for the Tired and Wired

I recently joined a friend to watch Cloud Atlas at her home. A bad choice for evening entertainment! This is a movie where evil is lurking around every corner.

New research on laboratory mice suggests why arousing activities have such a strong impact on sleep.

horror-movieI recently joined a friend to watch Cloud Atlas at her home. A bad choice for evening entertainment! This is a movie where evil is lurking around every corner, and the suspense in each of the six plotlines tied my stomach up in knots. We turned off the DVD player near bedtime, but unwinding enough to fall asleep took me nearly three hours. Even then my sleep was patchy and unsatisfying.

What we do and what we think about before bedtime has a big impact on our sleep. Aristotle had this figured out back in Ancient Greece. “The intellectual activities which cause wakefulness are those in which the mind searches and finds difficulties rather than those in which it pursues continual contemplation,” he wrote.

New research on laboratory mice suggests why arousing activities have such a strong impact on sleep. Researchers at UT Southwestern Medical Center have discovered two new proteins, one that tracks sleep need and the other that determines how long it takes to fall asleep. Their study, published last month in Proceedings of the National Academy of Sciences, showed that these two processes are separate, and that even mice that were sleep deprived did not fall asleep quickly when placed in an arousing environment.

Tired and Wired

The subjects in this experiment were three groups of mice with identical genes. The control group was allowed to sleep and wake up at will.

The two test groups were deprived of sleep for six hours. During this time, one test group underwent a series of cage changes. With each new cage change, the mice set about vigorously exploring their new surroundings for about an hour. Mice in the other test group were kept awake by a researcher gently tapping the cage or waving a hand in front of their faces.

When finally the mice in the two test groups were allowed to sleep, the second group dropped off right away. But the cage-exchange mice took as long to fall asleep as mice in the well-rested control group.

“The need to sleep is as high in the cage-changing group as in the gentle-handling group,” said Dr. Masashi Yanagisawa, lead author of the study, quoted in Science Daily. “But the cage-changers didn’t feel sleepy at all. Their time to fall asleep was nearly the same as the free-sleeping, well-rested control group.”

Moral of the Story

You can’t always control what happens in the evening, and it’s boring to be a shut-in while others are out having fun. But if sleep is what you’re after, follow the advice offered by Dr. A. Brigham in 1845: “Those who are liable to have disturbed sleep should take especial care that their evenings pass tranquilly.”

What kinds of evening activities typically disrupt your sleep?

The Sleepy Teen Problem

The thinking on teen sleepiness is getting complicated these days. On one hand, there’s reason to believe that American teens should get more sleep than they actually do.

On the other hand, a new review of literature published this month in the journal Sleep suggests the issue of children’s sleep need is far from settled.

sleepy-teenGot a sleepy adolescent who’s up texting at night and then dead to the world in the morning?

It seems like a no-brainer that teenagers who drift through breakfast like zombies should be getting more sleep, right? And the solution is equally obvious: confiscate their cell phones, turn off their computers, enforce a lights-out policy at 10 p.m. How else are they going to get the eight-and-a-half to ten hours recommended by venerable institutions like Harvard University and the National Heart, Lung, and Blood Institute?

But not so fast. The thinking on teen sleepiness is getting complicated these days. On one hand, there’s reason to believe that American teens should get more sleep than they actually do, say researchers at the University of Pennsylvania. Released this week, their findings suggest that increasing sleep duration to 10 hours a night could help cut down on adolescent obesity.

Recommended Sleep Times: Are They Valid?

On the other hand, a new review of literature published this month in the journal Sleep suggests the issue of children’s sleep need is far from settled. Consider, for instance, this fascinating factoid: at any given age, children from Asia sleep

  • 60 to 120 minutes less than children in Europe, and
  • 40 to 60 minutes less than children in the United States.

Not only do Asian children get less sleep, but they also report needing less sleep than their European and American counterparts. What to make of this huge discrepancy? Are children’s sleep needs determined by genetic differences or sociocultural context? Are Asian children catastrophically sleep-deprived?

The upshot of this review is that any recommendations you’ve ever heard about the sleep needs of teenagers are speculative and based on inadequate data, a fact which, in the words of sleep investigator Irwin Feinberg, “embarrasses our field.”

Feinberg, in an accompanying editorial, acknowledges that daytime sleepiness among adolescents is a major public health concern. Yet spending more time in bed may not help.

Changes in the Adolescent Brain

The human brain undergoes a major reorganization during adolescence, says Feinberg, and this reorganization has a dramatic effect on teenagers’ brains at night. Young children get lots of deep sleep. But the proportion of deep sleep children get begins to decline in early adolescence, and this is strongly related to an increase in daytime sleepiness.

Adolescence also brings a steep decline in a lighter stage of sleep characterized by theta brainwaves, says Feinberg, and that this decline correlates even more strongly with the steep rise in sleepiness in children as they move through their teenage years.

But here’s the kicker: the decrease in theta waves and the corresponding rise in sleepiness occur independent of how long teens sleep or how many hours they stay in bed.

So is there a solution for adolescents who can barely get dressed in time to catch the bus? Later starting times at middle and high schools may be part of the answer. As for the rest, it’s wait and see.

If you’ve got a sleepy teenager (or if you ever had one), what ways have you found to combat the problem?

Sleep and Adolescent Obesity

Insufficient Evidence on Children’s Sleep Needs

Countdown to a Good Night’s Sleep

Scientists have never found a way to determine how much sleep each person needs, so judgments about sleep need remain subjective.

But there is quite a range in sleep ability, or how much sleep people report that they get.

sleep-needJust how much sleep is enough?

It’s every man for himself (and every woman for herself) when it comes to answering this question. Only you know how much sleep you need to feel rested and ready for the day.

But advice-givers for hundreds of years have offered prescriptions about how much sleep people need as if it were a matter of standard hygiene. Rinse your face when you get up in the morning. Brush your teeth twice a day. Wash your hands after using the toilet. Get 7 to 8 hours of sleep a night.

In reality, scientists have never found a way to determine how much sleep each person needs, so judgments about sleep need remain subjective. But there is quite a range in sleep ability, or how much sleep people report that they get.

What the Numbers Say

Sleep scientist Daniel Kripke analyzed a survey of over a million people and found that while a majority reported sleeping 7 or 8 hours a night, about 8 percent reported sleeping 9 hours or more, 16 percent reported sleeping about 6 hours, and 4 percent said they slept 5 hours or less. The best survival rate occurred for people who reported sleeping 6.5 to 7.4 hours a night.*

An average night’s sleep for me falls well below this, but I don’t worry too much about my mortality. I don’t care about the numbers as long as I wake up feeling pretty good.

Pronouncements About Sleep Need from the Past

  • “Much sleep ingendereth diseases and payne,” says The Schoole of Vertue in 1557, “It dulles the wyt and hurteth the brayne.”
  • “Nature requires five (hours), custom takes seven, laziness nine, and wickedness eleven.”
  • “Ten to 11 hours for children, 9 to 10 hours for women and feeble persons, and 6 to 7 hours for men,” says an eighteenth century book of devotions.
  • “For the healthy normal human being of sedentary occupation to … spend much more than a quarter of his time in sleep, is lazy neglect of his duty to himself and the race, and a reversion toward the stage of the amoeba,” says Dr. Fred W. Eastman in The Atlantic Monthly in 1911.

How much attention did people pay to pronouncements like these when they were delivered? Who knows. What I do know is that when claims about sleep need sound prescriptive, you’re better off taking them with a grain of salt.

* Mortality Associated with Sleep Duration and Insomnia