Some people can’t go to sleep until late; others can’t sleep in. Both suffer “social jet lag.” Illustration by Nishant Choksi

Nathaniel Kleitman, known as the “father of modern sleep research,” was born in 1895 in Bessarabia—now Moldova—and spent much of his youth on the run. First, pogroms drove him to Palestine; then the First World War chased him to the United States. At the age of twenty, he landed in New York penniless; by twenty-eight, he’d worked his way through City College and earned a Ph.D. from the University of Chicago. Soon after, he joined the faculty there. An early sponsor of Kleitman’s sleep research was the Wander Company, which manufactured Ovaltine and hoped to promote it as a remedy for insomnia.

Until Kleitman came along, sleep was, as one commentator has put it, “a huge blind spot in the science of physiology.” No one bothered to study it because it was defined by what it wasn’t—sleep was a state of not being awake and, at the same time, of not being comatose or dead. (It’s unclear what exactly attracted Kleitman to this academically marginal topic, but it has been suggested that it fitted with his own marginalized background.)

In one of Kleitman’s first experiments, he kept half a dozen young men awake for days at a stretch, then ran them through a battery of physical and psychological tests. Frequently, he used himself as a subject. As a participant in the sleep-deprivation experiment, Kleitman stayed awake longer than anyone else—a hundred and fifteen hours straight. At one point, exhausted and apparently hallucinating, he declared, apropos of nothing in particular, “It is because they are against the system.” (Asked what he meant, he said he’d been under the impression that he was “having a heated argument with the observer on the subject of labor unions.”) In another self-administered experiment, Kleitman spent six weeks underground, in Mammoth Cave, Kentucky, trying to live according to a twenty-eight-hour day. (He found that he could not.)

In the early nineteen-fifties, Kleitman’s research was sponsored in part by Swift, the meatpacking company, which was interested in finding out whether feeding babies a high-protein diet would make them sleep more soundly. It was at this point that he—or, really, one of his graduate students—stumbled onto a great discovery. Casting around for a dissertation topic, the student, Eugene Aserinsky, decided to hook sleepers up to an early version of an electroencephalogram machine, which scribbled across half a mile of paper each night. In the process, Aserinsky noticed that several times each night the sleepers went through periods when their eyes darted wildly back and forth. Kleitman insisted that the experiment be repeated yet again, this time on his daughter, Esther. In 1953, he and Aserinsky introduced the world to “rapid eye movement,” or REM sleep. Another of Kleitman’s graduate students, William C. Dement, now a professor of psychiatry at the Stanford medical school, has described this as the year that “the study of sleep became a true scientific field.”

The discovery of REM sleep led to the elaboration of a whole taxonomy of sleep. In Stage 1, the brain emits what are known as theta waves, which are slower and more regular than the waves emitted by a brain that’s awake; in Stage 3, it emits delta waves, which are even slower and have a much higher amplitude. (A person can be woken from Stage 1 sleep by a slight noise; by Stage 3, he might sleep through a loud crash.) Primates, marine mammals, birds, even fish have their own sleep patterns. Mouse lemurs, from Madagascar, snooze for more than fifteen hours a day, but only an hour of this is REM sleep. Bottlenose dolphins sleep with half their brains; this prevents them from drowning. Thrushes catch up on sleep by taking “catnaps” of less than thirty seconds apiece.

New technologies have made the study of sleep cheaper, easier, and less intrusive. In 2003, one expert in the field announced the “dawn of the golden age of sleep research.” Since then, hundreds, perhaps thousands, of academic papers have been written on topics ranging from “sleep problems among Chinese school-aged children” to the “sleep behavior of the wild black rhinoceros.” Currently, in the United States alone, more than two thousand sleep clinics are in operation. All of which raises the question: If this is sleep research’s golden age, then why are we all so tired?

Of the many ways that things can go wrong in bed, sleep troubles are probably the most prevalent. According to a 2011 poll, more than half of Americans between the ages of thirteen and sixty-four experience a sleep problem almost every night, and nearly two-thirds complain that they are not getting enough rest during the week. The National Academy of Sciences estimates that fifty to seventy million Americans suffer from a “chronic disorder of sleep and wakefulness.” The results are dangerous as well as annoying. A recent study by the Centers for Disease Control and Prevention revealed that almost five per cent of adults acknowledge nodding off at the wheel at least once during the previous month. The U.S. Department of Transportation has determined that what might be called D.W.D.—driving while drowsy—causes forty thousand injuries a year in the United States and more than fifteen hundred deaths.

Our collective weariness is the subject of several new books, some by professionals who study sleep, others by amateurs who are short of it. David K. Randall’s “Dreamland: Adventures in the Strange Science of Sleep” belongs to the latter category. It’s a good book to pick up during a bout of insomnia.

Randall begins with an account of his own sleep problems, which include laughing, humming, grunting, bouncing, kicking, and, on at least one occasion, sleep-walking into a wall. He considers a range of possible explanations for the national exhaustion—too much light, too much warmth, too much avoirdupois—and finds them all compelling. The electric light bulb has made darkness optional, eliminating the enforced idleness that used to begin at sunset. Modern mattresses and bedclothes trap the heat that the body gives off as its core temperature drops each night. Obesity increases the chances of developing sleep apnea, a condition that combines choking and waking in an exhausting, sometimes life-threatening cycle. For all these reasons and more, Randall anticipates a bright future for the emerging field of “fatigue management.” One sleep expert he interviews predicts that “fatigue management officers” will soon be as common at major corporations as accountants. Like time, sleep, it turns out, is money.

Perhaps the most provocative claim that Randall has to make about sleep is that we’d all be better off doing it alone. Research studies consistently find, he writes, that adults “sleep better when given their own bed.” One such study monitored couples over a span of several nights. Half of these nights they spent in one bed and the other half in separate rooms. When the subjects woke, they tended to say that they’d slept better when they’d been together. In fact, on average they’d spent thirty minutes more a night in the deeper stages of sleep when they were apart. Randall cites the work of Neil Stanley, a sleep researcher at the University of Surrey, in England, who likes to say that there’s only one good reason to share a mattress.