Blame it on the Industrial Revolution. Or maybe on the light bulb. But ever since man met machine, sleep has been on the skids.
In 2001, 38 percent of U.S. adults said they were sleeping less than they were just five years earlier. Americans now average seven hours in bed per night, and close to 60 percent now report they have trouble sleeping at least a few nights every week.
Seduced by 24-hour casinos, Seinfeld reruns and the Internet, Americans have plenty of diversions to keep them wired and alert. Did we mention L.L. Bean, the store that never closes? There's always good old worry, the anguish of relationships gone wrong and, right up there with the best of the sleep-wreckers, the dour discomfort of gastroesophageal reflux.
The biggest sleep robber of all, however, is work—the puritan ethic gone haywire in an era of global markets. To accommodate the relentless pressure for productivity, we're sleeping less and spending less time in social and leisure pursuits; the resulting stress can steal away even more sleep. Consider this: We're not only missing more shut-eye, we're having less sex, too.
To some degree, we can sacrifice sleep to oblige other demands on our time, but we pay a high price for the privilege. The need for sleep, anchored in part to the most ancient rhythms of the planet, is etched deeply in our brains. When we interrupt the natural rhythm of day and night for any reason—even reveling—we risk setting off a cascade of problems.
What we do at night affects everything we do during the day—our ability to learn, our skills, our memory, stamina, health and safety. Most of all, it affects our mood: Chronic sleep disruption appears to be the single biggest trigger for depression.
Everyone has a troubled night sometimes, or even a run of them, which happens to the average person about once a year. It's part of being human, subject to stress and worry. But it's what we do in response to it, experts say, that determines whether we will wind up with chronic insomnia. It turns out that the best thing to do in response to a bout of sleeplessness is often, well... nothing at all.
Two Systems, One Sleep
Recently, scientists have come to recognize that sleep is regulated by two entirely different systems. The knowledge that we have two roughly parallel forces guiding our need for sleep has opened the bedroom door to multiple ways of treating insomnia.
One force is the sleep homeostat. This functions like a drive that "builds up during wakefulness in pretty much a linear fashion and is discharged when you sleep," explains Arthur J. Spielman, associate director of the Center for Sleep Medicine at New York Presbyterian-Cornell Medical College. The homeostatic pressure to sleep depends not only on how long you are awake but on how active you are while awake.
But if you build up a need for sleep in a linear fashion, one would think you'd get sleepier as the day proceeds. It doesn't happen quite that way. Enter circadian rhythm, the body's biological clock. The circadian system is tied, albeit imperfectly, to cycles of light and dark. We have dedicated sensors on the retina that deliver the daytime/nighttime message directly to the pineal gland tucked deep inside the brain. In response to darkness, this tiny nodule of brain tissue produces the sleep-inducing hormone melatonin, broadcasting the sandman's message to brain areas that govern everything from body temperature to protein synthesis to hormone production to alertness.
Circadian rhythm guides the body through cycles of sleep and alertness. Ironically, it issues its strongest alerting force in a burst lasting from 6 p.m. to 8 p.m., perfect for dinner-party repartee (although you may not remember the bon mots—short-term memory is sharpest around 7 in the morning). After 8 p.m., alertness begins to fade, permitting us to doze off. This same system makes us sleepiest in the early morning, from 4 a.m. to 6 a.m. Stay up all night studying for an exam and circadian forces will make you drowsy near dawn. Stick it out for two more hours, though, and you'll start picking up steam again. "You don't need sleep to actually get alert," Spielman points out.
Understanding this cycle can help some people who have trouble falling asleep or getting back to sleep. Manipulating the circadian rhythm with bright lights in the morning or melatonin in the evening, says Spielman, can help.
By the same token, it's possible to ramp up the sleep drive by tinkering with the sleep homeostat. Two of the best methods are exercise and heating the body. Grandma was right about that warm bath before bedtime, although she may not have known why. As it turns out, sleep naturally follows a sharp drop in body temperature. So lying still in bed after a hot bath may be just what your body needs to drift off.
Many of us complain that we struggle to get enough sleep. But insomnia is one of those words we toss around a bit too freely. Experts generally apply the "30-30 rule": It's insomnia if it takes you 30 minutes or more to fall asleep or if you're awake for 30 or more minutes during the night—at least three times a week. No matter how little you sleep, it isn't insomnia unless your nighttime habits drag you down during the day.
Those who have trouble falling asleep or waking up may not technically have insomnia but instead be suffering from "sleep-phase disorder." In this case, people have unwittingly trained themselves to conk out at the wrong time. It's especially common among adolescents and college students—those who yield to all the siren calls for their time, don't get to sleep before 3 a.m. or 4 a.m. and then can't get up for classes. (If you have insomnia four or five nights a week but not on weekends, you probably have a phase-shift problem.)
