Before the discovery of rapid eye movements, our understanding of sleep hadn’t undergone any dramatic revisions in more than two thousand years. The Ancient Greeks believed that someone fell asleep when the brain became filled with blood, and then woke up once it drained back out again. Beyond that, they found the whole experience kind of spooky. Sleep was considered the closest a living being could come to death and still be around to talk about it afterward. The immortal family tree made this clear: Hypnos, the Greek god of sleep, was the twin brother of Thanatos, the god of death, and their mother was the goddess of night. It was probably best not to think about this too much while lying in a room on a dark and lonesome evening. Two-dozen centuries later, doctors put forth the theory that blood flowing through the head put pressure on the brain and induced sleep, a concept Plato would have readily agreed with. Philosophers in the nineteenth century introduced the novel idea that a person fell asleep when the brain ceased to be filled with stimulating thoughts or ambitions. The supposed link between sleep and an empty head fostered a suspicion of anyone who slept too much or seemed to enjoy it. In certain high-pressure jobs today, admitting that you sleep for more than five or six hours each night still looks to be a sure sign that you are not a serious person.
Whether any of us has a sleep problem or not, it is clear that we are living in an age when sleep is more comfortable than ever and yet more elusive. Even the worst dorm-room mattress in America is luxurious compared to sleeping arrangements that were common not that long ago. During the Victorian era, for instance, laborers living in workhouses slept sitting on benches, with their arms dangling over a taut rope in front of them. They paid for this privilege, implying that it was better than the alternatives. Families up to the time of the Industrial Revolution engaged in the nightly ritual of checking for rats and mites burrowing in the one shared bedroom. Modernity brought about a drastic improvement in living standards, but with it came electric lights, television, and other kinds of entertainment that have thrown our sleep patterns into chaos.
Work has morphed into a twenty-four-hour fact of life, bringing its own set of standards and expectations when it comes to sleep. As the Wall Street banker who follows investments simultaneously in Dubai, Tokyo, and London knows, if you aren’t keeping up, you risk being left behind. Sleep is ingrained in our cultural ethos as something that can be put off, dosed with coffee, or ignored. And yet maintaining a healthy sleep schedule is now thought of as one of the best forms of preventative medicine.
Stanford University, one of the world’s premier centers of sleep research, established the first university laboratory center devoted to treating sleep disorders in 1970. The opening of Stanford’s clinic started a revolution in the way the medical field approached sleep. Until then, most doctors thought that their responsibility ended once a patient nodded off each night. By 2011 there were over seventy-five recognized sleep disorders, and the number continues to grow. Some, like sleep apnea, are so common that if they aren’t present in your bedroom, there is a very good chance you will find them next door. Others are simply baffling. One rare type of prion disease called fatal familiar insomnia strikes after a person reaches the age of forty. This genetic disease has been found in only a handful of families around the world. Its chief symptom is the gradual inability to fall asleep. Within a year of the first signs of the condition, patients typically die after suffering through months of agony, beset by chronic migraines and exhaustion. Their minds remain clear and unaffected until death.
There is more to sleep than medical curiosities, however. This is a book about the largest overlooked part of your life and how it affects you even if you don’t have a sleep problem that sends you into a wall in the middle of the night. I began my research into sleep with the self-serving intention of finding a way to prevent future run-ins. But as I spent more time investigating the science of sleep, I began to understand that these strange hours of the night underpin nearly every moment of our lives. Police officers, truck drivers, and emergency-room physicians, for instance, are turning to sleep researchers for help in navigating sleep’s effects on the brain’s decision-making process. If you have ever flown on an airplane, gone to a hospital, or driven on a highway at night—or plan on doing so in the future—then you have a vested interest in how companies and organizations try to prevent costly and deadly accidents caused by something as manageable as fatigue. School districts across the country, meanwhile, have changed the time that the first bell rings in the wake of research showing that simply starting the school day later leads to significantly higher SAT scores. And new studies suggest that learning a new skill or finding a solution to a problem may simply be an outcome of the time that we spend dreaming each night.
Because of the number of new findings in such a short time span, today’s researchers believe that they are in the golden age of their field. Sleep is now understood as a complex process that affects everything from the legal system to how babies are raised to how a soldier returning from war recovers from trauma. And it is also seen as a vital part of happiness. Whether you realize it or not, how you slept last night probably has a bigger impact on your life than what you decide to eat, how much money you make, or where you live. All of those things that add up to what you consider you—your creativity, emotions, health, and ability to quickly learn a new skill or devise a solution to a problem—can be seen as little more than by-products of what happens inside your brain while your head is on a pillow each night. It is part of a world that all of us enter and yet barely understand.
Sleep may not immediately come across as the most adventurous topic to investigate. After all, people who are sleeping are usually just lying there, making it very hard to interview them. What could possibly be interesting about that? My aim is to convince you otherwise by taking you on a tour of often odd, sometimes disturbing, and always fascinating things that go on in the strange world of sleep, a land where science is still in its infancy and cultural attitudes are constantly changing. I will take you through the story of a night, starting with the unrecognized forces at work in your bedroom as you fall asleep and ending with the latest research into what goes into a good night’s rest.
This is not your typical advice book filled with ten easy steps to perfect sleep. But you will come away with a new understanding of all that goes on in your body while you are sleeping and what happens when you neglect sleep for too long. Hopefully, this will inform your future decisions affecting everything from your health to your wallet. You don’t have to take my word for it. By the end of this book, you will have met, among others, dream researchers, professional sports trainers, marriage counselors, pediatricians, constitutional scholars, gamblers, and a university professor who investigates what could only be called sleep crime.
I never found the cure for sleepwalking that I was looking for, though I did learn what I could do to make it less likely to happen again without resorting to medication. But no matter what steps I take, or how much yoga I do to relax myself before bedtime, I very well may wake up once again in the middle of the night, disoriented and away from my bed. On the other hand, I may never sleepwalk again. That’s the bizarre beauty of sleep, a seemingly simple part of life with more possible outcomes each night than you can imagine. I’ve been to military bases and corporate headquarters, campus labs and convention centers, all in search of what we can learn from this curious and universal fact of life if we took the time to examine it.
Sleep isn’t a break from our lives. It’s the missing third of the puzzle of what it means to be living.
2
Light My Fire
If you wanted to find Roger Ekirch for most of the 1980s and 1990s, the first and best place to look was between the gray stone walls of the Virginia Tech University library. A young professor of history who taught courses about life in the early United States, Ekirch spent most of his days giving lectures to undergraduates about the early slave trade or the once-booming pirate economy of the Atlantic. But wh
enever he could, he sequestered himself among the rare-book collection. It was there that he could indulge a topic that had intrigued him since graduate school: the history of the night.
At the time, most historians would have readily agreed that human activity after the sun went down was reduced to “no occupation but sleep, feed and fart,” as Thomas Middleton, a playwright who was friends with Shakespeare, once so eloquently put it. But Ekirch continued the lonely work of prying open the pages of mildewing books, noting any hints that something interesting happened after the close of each day. He didn’t know he was on the path of a major breakthrough that would change our conception of how the human brain is built for sleep. He was a history professor, after all, whose only understanding of sleep consisted of knowing that he liked it. But as he searched through plays, wills, and all of the other assorted artifacts of daily life that had accumulated over the last thousand years in Europe, he realized that the sun’s fall into the horizon set the stage for a bizarre twelve hours.
Nightfall on an average day of the week brought about a fear so harrowing to a villager in medieval Europe that we can scarcely conceive of it today. At the first hints of sunset, farmers raced to get inside a city’s walls before they were locked at night. Anyone not fast enough would have to survive the dark hours in the wilderness alone, fending off robbers, wolves, and the ghosts and devils lurking around every corner.
The cities weren’t much safer. If you were to find yourself on the streets at night, the logical assumption was that everyone you encountered was intent on robbing or killing you. Striking first became the best option. Past nightfall, “clashes of all sorts became likely when tempers were shortest, fears greatest, and eyesight weakest,” Ekirch noted. He found stories of servants stabbing each other in the armpit “without provocation,” merchants getting into sword fights with their neighbors on the streets of London, and the sound of dead bodies splashing into the canals of Venice—all a common part of life after dark. In these times, when most everyone who ventured outside at night did so armed with at least a knife, a polite greeting was less of a formality and more of a way to stay alive.
The hours of the night were so starkly different that they had their own cultural rhythms. Townspeople who took pride in their ability to fend for themselves during the day willfully submitted to curfews, literally locking themselves into their homes at night. Rural farmers who would never see an ocean in their lifetimes knew how to tell time and direction from the stars, just like sailors. Monarchs and bishops demonstrated their authority over the elements by staging elaborate ceremonies and dances illuminated by hundreds of torches, dazzling the eyes of peasants who relied on stinky, smoky, and dim candles to light their small houses.
Yet something puzzled Ekirch as he leafed through parchments ranging from property records to primers on how to spot a ghost. He kept noticing strange references to sleep. In the Canterbury Tales, for instance, one of the characters in “The Squire’s Tale” wakes up in the early morning following her “first sleep” and then goes back to bed. A fifteenth-century medical book, meanwhile, advised readers to spend the “first sleep” on the right side and after that to lie on their left. And a scholar in England wrote that the time between the “first sleep” and the “second sleep” was the best time for serious study. Mentions of these two separate types of sleep came one after another, until Ekirch could no longer brush them aside as a curiosity. Sleep, he pieced together, wasn’t always the one long block that we consider it today.
From his cocoon of books in Virginia, Ekirch somehow rediscovered a fact of life that was once as common as eating breakfast. Every night, people fell asleep not long after the sun went down and stayed that way until sometime after midnight. This was the first sleep that kept popping up in the old tales. Once a person woke up, he or she would stay that way for an hour or so before going back to sleep until morning—the so-called second sleep. The time between the two bouts of sleep was a natural and expected part of the night and, depending on your needs, was spent praying, reading, contemplating your dreams, urinating, or having sex. The last one was perhaps the most popular. One sixteenth-century French physician concluded that laborers were able to conceive several children because they waited until after the first sleep, when their energy was replenished, to make love. Their wives liked it more, too, he said. The first sleep let men “do it better” and women “have more enjoyment.”
Ekirch was faced with the classic crisis of the scholar: here in front of him was mounting evidence that how we sleep today is nothing like the sleep of our ancestors. Yet saying that the whole of the industrialized world sleeps unnaturally was a big leap, especially for a professor who was more versed in the agrarian economy of the American colonies than in neuroscience. Even years later, Ekirch couldn’t be sure that he would have publicized his findings without a bit of luck. “I would have hoped that I would have had enough confidence in my research to go ahead with the idea on my own,” he told me, sounding like a man trying to build his confidence through a barrage of words.
Fortunately for him, he didn’t have to. About three hundred miles away, a psychiatrist was noticing something odd in a research experiment. Thomas Wehr, who worked for the National Institute of Mental Health in Bethesda, Maryland, was struck by the idea that the ubiquitous artificial light we see every day could have some unknown effect on our sleep habits. On a whim, he deprived subjects of artificial light for up to fourteen hours a day in hopes of re-creating the lighting conditions common to early humans. Without lightbulbs, televisions, or street lamps, the subjects in his study initially did little more at night than sleep. They spent the first few weeks of the experiment like kids in a candy store, making up for all of the lost sleep that had accumulated from staying out late at night or showing up at work early in the morning. After a few weeks, the subjects were better rested than perhaps at any other time in their lives.
That was when the experiment took a strange turn. Soon, the subjects began to stir a little after midnight, lie awake in bed for an hour or so, and then fall back asleep again. It was the same sort of segmented sleep that Ekirch found in the historical records. While sequestered from artificial light, subjects were shedding the sleep habits they had formed over a lifetime. It was as if their bodies were exercising a muscle they never knew they had. The experiment revealed the innate wiring in the brain, unearthed only after the body was sheltered from modern life. Not long after Wehr published a paper about the study, Ekirch contacted him and revealed his own research findings.
Wehr soon decided to investigate further. Once again, he blocked subjects from exposure to artificial light. This time, however, he drew some of their blood during the night to see whether there was anything more to the period between the first and second sleep than an opportunity for feudal peasants to have good sex. The results showed that the hour humans once spent awake in the middle of the night was probably the most relaxing block of time their lives. Chemically, the body was in a state equivalent to what you might feel after spending a day at a spa. During the time between the two sleeps, the subjects’ brains pumped out higher levels of prolactin, a hormone that helps reduce stress and is responsible for the relaxed feeling after an orgasm. High levels of prolactin are also found in chickens while they lay atop their eggs in a contented haze. The subjects in Wehr’s study described the time between the two halves of sleep as close to a period of meditation.
Numerous other studies have shown that splitting sleep into two roughly equal halves is something that our bodies will do if we give them a chance. In places of the world where there isn’t artificial light—and all the things that go with it, like computers, movies, and bad reality TV shows—people still sleep this way. In the mid-1960s, anthropologists studying the Tiv culture in central Nigeria found that group members not only practiced segmented sleep, but also used roughly the same terms of first sleep and second sleep.
You would think that investigations showing that our modern sleep habits r
un contrary to our natural wiring would be a pretty big deal. But almost two decades after Wehr’s study was published in a medical journal, many sleep researchers—not to mention your average physician—have never heard of it. When patients complain about waking up at roughly the same time in the middle of the night, many physicians will reach for a pen and write a prescription for a sleeping pill, not realizing that they are medicating a condition that was considered normal for thousands of years. Patients, meanwhile, see waking up as a sign that something is wrong. Without knowing that sleep is naturally split into two periods, it’s hard to blame them.
Why do roughly six billion humans sleep in a way that is contrary to what worked for millions of years? Because of a product that was once revolutionary and now costs less than two dollars: the lightbulb. The lamp next to your bed contains a device that has changed human sleep perhaps forever, and ushered in a new world of health problems that come from an overabundance of light. Nearly every aspect of modern life originated in a complex of weathered brick buildings surrounded by a black metal fence in northern New Jersey. Here, in an idea factory that predated the startups of Silicon Valley, an inventor with a talent for self-promotion named Thomas Alva Edison forged the devices that upended how our bodies are designed to sleep.
Dreamland: Adventures in the Strange Science of Sleep Page 2