Not sleeping well? It's a common complaint. Sixty-four million Americans report at least occasional bouts of insomnia. And the anxiety of waking up in the middle of the night can be maddening.
Psychiatrist Thomas Wehr has one consoling message for those who wake up at 2 a.m.: This is likely the way our ancestors slept.
"There are historical records of people sleeping in two bouts at night," Wehr explains. They called the first bout dead sleep, and the second bout was called morning sleep. The wakeful period in between was referred to as watch or watching.
Before the days of artificial lighting, a winter day could bring 14 hours of solid darkness. People lived from sun to sun.
Wehr was curious as to what might happen if he put busy Americans into that environment. How would they sleep? He organized a study to find out.
He and his colleagues at the National Institute of Mental Health recruited 15 young, healthy adult volunteers. They went about their normal business during the day, then reported to a sleep lab in the early evening.
"We had our subjects go into the dark at 6 p.m., lie down and rest," Wehr says. The lights didn't come back on until 8 the next morning; it was a simulated winter day.
The sleep study found that the long night led to two bouts of concentrated sleep — with a wakeful period in the middle, lasting a few hours. The study was published in the American Journal of Physiology in 1993.
"You might think that lying awake for two hours would be a kind of torture," Wehr says. "But it wasn't at all." The people in the sleep study described it as a kind of quiescent, meditative state.
Researchers found similar results in a more recent study of adolescents. The longer night seems to give rise to a sort of "midnight comfort."
Learn more about what our sleep patterns say about our health.
To many of us, the notion of staying in bed — or in the dark — for 12 hours may seem ridiculous or a waste of time. In modern culture, we've adapted to a more efficient way of sleeping: consolidating it into one long stretch.
This works for many people, but as we age, sleep changes.
"Sleep tends to be more fragile in general as we age," says Mary Carskadon, who directs chronobiology and sleep research at Brown University.
One way to assess the age-related changes in sleep is to look at brain waves.
"When we're little, we have a lot of very high, slow brain waves at the beginning of the night," Carskadon says. "And that seems to be the best, most restorative kind of sleep."
But as the decades go by, these peaks diminish. If adolescent brain waves are the Himalayas, then by early adulthood, they're Rocky Mountain peaks. And in the elderly: think Appalachians or just foothills.
As we age, it's easier to wake us, Carskadon explains, "because those high, slow waves are very protective for disturbances in the environment" — things such as a snoring partner, or a barking dog.
Getting Enough Zzzzzzzz
So, if interruptions in sleep are to be expected, what's the best strategy for getting enough of it?
One option is to embrace a longer night. This may work for people who have very flexible schedules, or for those who are retired.
"They can afford, arguably, to spend more time in bed," says Jack Edinger, a sleep expert at Duke University. He says the middle-of-night wake time may not be anxiety-provoking if you know you're going to get another bout of morning sleep.
There's also the siesta model — with naps in the afternoon. But for those of us who need to get up and work all day? There are strategies that can help people consolidate sleep.
One technique, according to Edinger, is to tightly restrict the number of hours in bed. This encourages more efficient sleep.
Edinger stresses that sleep requirements vary from person to person. Six to nine hours is the normal range. But "there are people who fall outside that range and do just fine," he says.
The important thing is to get a good handle on the dose of sleep YOU need, he says. Set your pattern — and stick with it each night.
Most of us will find that's seven or eight hours. Recent studies suggest that people who get less than seven hours each night tend to be more susceptible to the common cold and weight gain.