Developing a few habits with the circadian rhythm in mind will most likely make sleep easier. Adequate exposure to natural light, for instance, will help keep the body’s clock in sync with the day-night cycle and prime the brain to increase the level of melatonin in the bloodstream, which will then bring on sleepiness around ten o’clock each night. By the same token, bright lights—including the blue-and-white light that comes from a computer monitor or a television screen—can deceive the brain, which registers it as daylight. Lying in bed watching a movie on an iPad may be relaxing, but the constant bright light from the screen can make it more difficult for some people to fall asleep afterward. Other common suggestions from sleep doctors include maintaining a consistent bedtime, using the bedroom only for sex or sleeping, and turning the lights down low in the home about a half hour before climbing into bed.
Recent studies have shown that body temperature also plays an outsized role in getting decent sleep. In addition to the appearance of brain waves like sleep spindles, one of the biological markers of the onset of sleep is a drop in core body temperature. At the same time, the temperature of the feet and hands increases as the body gives off heat through its periphery, which explains why some people like to have their feet sticking out of the covers as they fall asleep. The body’s tendency to release heat during the night is one reason why some mattresses are said to be uncomfortable—they “sleep hot.” In the simplest explanation, the fabric and materials that make up some beds trap the heat the body is releasing. The result can make the bed feel like an oven, preventing the body from cooling itself down. The core temperature of the body falls naturally for most of us after ten o’clock each night as a result of the circadian rhythm. When this doesn’t happen, chronic insomnia is often a result. Researchers at an Australian university found that patients with insomnia had significantly higher core body temperatures when attempting to fall asleep than those who identified themselves as good sleepers.
Assisting the body in its cooling process, then, is a natural way to improve sleep. One study by researchers in Lille, a city in northeastern France, found that subjects fell asleep faster and had a better overall quality of sleep following behaviors that cooled the body, such as taking a cold shower right before bed. The best predictor of quality sleep was maintaining a room temperature in a narrow band between 60 and 66 degrees Fahrenheit (or 16 to 19 degrees Celsius). Temperatures above or below this range often led subjects to become restless, either tossing or turning from being too hot or shivering from the cold. The study assumed, of course, that the subjects were sleeping in pajamas with at least one sheet covering them. Being tenacious researchers, the French team also investigated the proper room temperature for those who prefer to sleep naked. They found that it was a much higher range, 86 to 90 degrees Fahrenheit, or 30 to 32 degrees Celsius.
Lowering the body’s temperature is not the only physical activity that can make the night easier. Even a small increase in the amount of exercise a person gets leads to measurable improvements in the time that it takes to fall asleep and stay that way. This is particularly true for older adults. In one study of men and women with clinical depression, undergoing ten weeks of weight training resulted in significant improvements in sleep quality. Another study of sedentary adults with a history of sleep problems found that a four-month exercise regiment dramatically reduced the time it took them to fall asleep. And in one of the most intriguing studies, researchers in Seattle tracked nearly two hundred overweight or obese women over the age of fifty for one year. At the beginning of the study, each woman averaged less than an hour of moderate to vigorous exercise each week. One group of subjects agreed to stick with an exercise program for the next twelve months, and the rest maintained their normal lifestyle. A year later, it wasn’t surprising that those who exercised reported a better quality of sleep than those who remained sedentary. But there were also significant differences in sleep quality among the women who exercised. Those who spent more than three and a half hours involved in physical activities each week had less trouble falling asleep than those who exercised for less than three hours.
At first glance, it appears obvious that exercise’s benefit for sleep is simply a matter of physical exhaustion. After all, those women who slept the best were also the ones who were the most active. Maybe their bodies were so depleted that they just needed more sleep. But the relationship between sleep and exercise is yet another instance in which the brain isn’t as straightforward as it seems.
What may matter more than the amount of time spent doing strenuous physical activity is how hard the brain considers the work to be. One study, completed by Swiss researchers and published in the Journal of the American College of Sports Medicine, focused on nearly nine hundred college students in Switzerland. Each person in the study tracked how much he or she exercised during the week. Subjects were also asked to fill out two questionnaires. In one, they rated how well they slept, on a scale of 1 to 10. In the other, they rated their overall fitness level, again on a scale of 1 to 10. Overall, the research team found no link between how many hours a student spent working out and how well he or she slept each night.
The self-assessments uncovered other surprising results, however. Nearly a fifth of those who rated themselves low on the fitness scale were, in reality, among the most physically active participants in the entire study group. These subjects were working out all the time, but they simply felt like they weren’t doing enough. Those perceptions carried over into their sleep. Although they were more active than other members of the study, subjects in this group reported sleep qualities that were below average. They were doing the work but not getting the rewards.
This followed the findings of other studies which discovered that the connection between exercise and sleep isn’t just a matter of tiring oneself out. One, for instance, tracked college students for a little longer than three consecutive months. At the end of this time span, researchers went back and identified the eleven days on which subjects were the most physically active and the eleven days with the lowest amount of movement. They then compared a subject’s quality of sleep on the nights after he or she was the most physically taxed with the quality on the nights after he or she presumably had energy to spare. Logic would hold that a busier day means a better sleep. But there was little difference. The study found no relationship between an individual activity level during the day and the quality of sleep that night, which means that a long run alone won’t provide the answer to a better night’s sleep.
But the same study did uncover one of the brain’s quirks. Intriguingly, the subjects who thought they were in good shape slept well—even if they weren’t actually exercising as much as others in the study. It appeared that whatever amount of time these subjects spent working out was enough to cross the mental threshold that told them not to worry about their fitness level. As they laid down each night, their lack of concern about whether they were exercising enough gave them one less thing that could stand in the way of drifting off to sleep. Their minds thought their bodies were meeting the standard, and they acted accordingly. As the lead researcher for the Swiss study told the New York Times, “What people think is more important than what they do.”
This same principle applies to other tactics to improve sleep that could fall under the general category of holistic medicine. Yoga, acupuncture, and massage have all been linked with improved sleep, in part because they put both the body and the mind at ease. The mental aspect of each activity can’t be overlooked. In one study, patients were asked to do a form of breathing exercises that would be familiar to anyone who has finished a yoga class in corpse pose. As subjects laid on their back with their eyes closed each night, they were instructed to focus on their breathing by thinking the word in every time they inhaled and out with each exhalation. The technique proved as effective as other forms of relaxation strategies used to treat insomnia.
The secret of the Zeo, for all of the technology that goes into capturing a person�
�s brain waves and translating them into a number that rates each night of sleep, may be that it accomplishes the same thing as these mental techniques. By providing feedback in the form of an easily understood scale, the device could simply be giving its users the same sense of satisfaction that those lucky Swiss college students felt. They weren’t among the most physically active in a literal sense, but reality didn’t matter. Their minds believed that they were fit, so therefore they acted—and slept—accordingly. The secret to a good night’s rest could just be stopping the mind from getting in its own way.
13
Good Night
When I began this book, I did so with a selfish plan. By interviewing experts specializing in every aspect of sleep science, I expected to come away from the project with all of my own sleepwalking problems solved.
It didn’t quite work out that way. This was never more obvious than on a hot July afternoon I spent in San Antonio. I was there for the largest annual meeting in the country of the doctors, researchers, and academics who make the study of sleep their lives. There, spread out across a convention floor the size of four football fields, were booths selling every imaginable product that could possibly affect a person’s sleep. Some vendors sold T-shirts with pockets of air stitched into the back, claiming they prevented snoring by forcing a person to sleep on his or her side. Beside them were floor-to-ceiling booths from companies marketing pills for patients with narcolepsy and other disorders. One floor display was so large there was enough room for a chef wearing a tall white hat to bake warm peanut butter cookies in the middle of it. And in front of me, wearing a bright red shirt, was a man named Mike.
Mike’s product looked to be nothing more than a big glass jar on top of a record player. Inside the jar was a lifelike plastic rat with wires attached to its temples. If this had been a real rat, then it wouldn’t have liked its predicament. That’s because the entire purpose of the machine was to keep the animal awake for long stretches at a time without any human labor. Apparently, keeping a rat from falling asleep is harder than it looks. “It’s very labor-intensive,” Mike said, and I don’t doubt him. “If you’re a university, you’re relying on grad students having to poke them. They’ve got to keep that up for a day or two, maybe three if they really want to finish their thesis.”
Mike worked for a company in Kansas called Pinnacle Technology. For $7,500, I could have purchased the 8400-K1-Bio machine that stood in front of me. The selling point of the system, Mike explained, was that it was guaranteed to keep a mouse or rat awake without painful electric shocks, which could corrupt the data of sleep deprivation experiments. Mike pointed out its features. If the rat fell asleep, the tiny neurotransmitter wires on its head would recognize it in an instant. The machine would then spring to action. In less than a second, the heavy plastic rod that was resting against the plastic rat’s feet would start whirling around, and keep at it until the rat woke up. No poking required.
It was a product that said more about sleep than it intended. As I looked at the machine, a realization arrived fully formed in my head: the more you know about sleep, the more its strangeness unnerves you. Before that moment, I would never have conceived of a product whose sole purpose was to deprive rats of sleep. And before I started this book, I wouldn’t have thought that sleepwalkers can kill, or that companies hope millions of people in China consume fast food and develop obesity-related sleeping disorders, or that one of the most popular prescription drugs works by making it harder for someone to form memories. Even after spending hundreds of hours with experts in various fields and reading a tall stack of research reports, I still saw sleep as this strange part of life that was all the more mysterious because of its importance. The existence of Mike’s machine suggested that there were still more puzzling aspects of sleep to be found, more researchers designing odd studies searching for the purpose of sleep, and more outcomes than one would think possible.
There was an upside to my newfound knowledge of this strange world, however. By that point, I knew enough about sleep that I began to improve my own. Unlike most people with a sleep problem, insomnia had never been an issue for me. Instead, my troublesome nights were, and are, those that I spend kicking, talking, or at their worst, walking down the hallway while still dreaming.
My sleep improvement plan was relatively simple. The first step consisted of using a Zeo, the brain wave–tracking device, for a month. Like the first testers of the product, I too was drawn to the fact that I could see in front of me a record of all of my previous nights of sleep, from the times that I woke up to the hours I spent dreaming. On the first night that I used the device, my ZQ rating was a 40—or about a third of the way on the scale in which 120 was the perfect night of sleep. I wasn’t surprised by the low number, considering the fact that I was attempting to sleep with a brain-wave monitor on my head. I had slept poorly during the night I spent in the professional sleep lab, too. The next night the headband felt slightly more natural. When I woke up, I sensed that I had had a normal night of sleep. My ZQ rating jumped to a 68. The machine revealed that I had woken up several times during the night that I couldn’t remember, but by that time that fact had ceased to be alarming. I also had spent what seemed like an adequate amount of time in dreaming sleep. That morning my wife said that she vaguely remembered hearing me talk in my sleep, but nothing out of the ordinary.
Still, I wanted to boost my ZQ up to at least 100. Maybe doing so would recalibrate my sense of what a good night of sleep really was. I started following all of the advice that I had received over the months. I began eating breakfast in the sunniest corner of our apartment every morning in order to improve my body’s synchronization with the day-night cycle. I became a fixture at yoga classes at the gym. And I roamed around the apartment turning lights off a half hour before I went to sleep. Each night, I continued to place the Zeo headband on and track my results. My ZQ score climbed steadily, rising from 68 one night to a 74 the next and all the way up to 88.
It peaked at a 94. I never made it to my self-imposed goal of a 100, but I was comforted by the fact that every other measure of my sleep improved. I woke up feeling more refreshed than normal. I had an easier time remembering things like where I put my keys and the date and time of my next dentist appointment. And the subway commute into and out of midtown Manhattan every workday felt calmer. Most important, I began to get a better sense of my body when it came to sleep. After one particularly stressful day at work, I felt an odd sensation as I got ready for bed: for some reason, I could tell that I was going to have a rough night sleep talking or kicking. Instead of fighting this fact, or worse yet, ignoring it, I understood enough about sleep to realize there was little I could do to prevent it on this night. I decided to sleep on the couch.
At first glance, it doesn’t seem that sleeping better was all that life-changing. After all, there is no guarantee that I won’t sleepwalk again into one of my hallway walls, or, even worse, sleepwalk into something more painful. I may sleepwalk again tonight, two Tuesdays from now, or perhaps never again. That’s just another part of the puzzle of sleep. But, though its effects were subtle, devoting extra time and attention to this most basic of human needs impacted nearly every minute of my day. Because I was improving my sleep, I was improving my life. And all it took was treating sleep with the same respect that I already gave other aspects of my health. Just as I wouldn’t eat a plate of chili-cheese fries every day and expect to continue to fit into my pants, I structured my life around the idea that I couldn’t get only a few hours of sleep and expect to function properly. If there was one thing that I took away from my talks with experts more than any other, it is that getting a good night’s sleep takes work.
And that work is worth it. Health, sex, relationships, creativity, memories—all of these things that make us who we are depend on the hours we spend each night with our heads on the pillow. By ignoring something that every animal requires, we are left turning to pills that we may not need, experiencing health probl
ems that could be tamed, and pushing our children into sleep-deprived lives that make the already tough years of adolescence more difficult. And yet sleep continues to be forgotten, overlooked, and postponed. Any step—whether it comes in the form of exercise, therapy, or simply reading a book like this one—that helps us to realize the importance of sleep inevitably pushes us toward a better, stronger, and more creative life.
Sleep, in short, makes us the people we want to be. All you have to do is close your eyes.
Acknowledgments
This is a book that came about because I hurt myself. Everything that has happened to me since that night suggests that sleepwalking can be one of life’s happy accidents.
I have been extremely fortunate to work with a team of smart, dedicated people, starting with my agent pair of Larry Weissman and his wife, Sascha Alper. Together, they calmly guided me through a process that took us from shaping the proposal over drinks in their living room to talking through the edits of the final manuscript. Along the way, they never wavered in their enthusiasm for the project. While we were walking in Park Slope one night, Larry gave me just the advice that a fretting first-time author needs: “Dave, remember that it’s a marathon.” With that, every writing or research problem seemed manageable.
Dreamland: Adventures in the Strange Science of Sleep Page 21
