Sleep isn't just a chunk of time carved out to recharge for the following day. Increasingly, scientific evidence shows life and sleep are woven together like 800-thread-count sheets. How people fare during their waking hours has a lot to do with how they sleep -- and vice versa.
Income, employment status, relationship satisfaction and hobbies all affect sleep, according to research presented last week in Seattle at the annual meeting of the Associated Professional Sleep Societies. And sleep affects health, relationships and decision-making.
"Sleep is related to everything," said Michael Grandner, a fellow at the Center for Sleep and Respiratory Neurobiology at the University of Pennsylvania.
Some news from the meeting:
Who can't sleep? In one presentation, Grandner reviewed responses from 159,856 people who participated in a government survey -- one of the largest to gather data on sleep difficulties. Overall, one in five people reported problems with sleep on seven of the 14 nights before the survey. Grandner found little difference among racial and ethnic groups, except for people of Asian ethnicity, who had far fewer problems.
But people in lower socioeconomic levels, especially women, reported more problems. So did divorced and separated people, especially divorced and separated men.
And men who described themselves as homemakers reported sleep problems on par with people who were unemployed (who had high rates of problems).
Perhaps most surprising, the worst sleep seems to occur in men and women ages 18 to 24. "The story with age is fascinating," Grandner said. "Usually, the common knowledge is that as you get older you have more sleep problems. We found pretty much the opposite."
It could be that older people are accustomed to sleep disturbances and don't complain about them, he said. But it still remains to be seen why so many young, ostensibly healthy people are missing out on their sweet dreams.
Cooling the brain: Treatments for insomnia include medications and lifestyle changes, neither of which appeal to some people. But research on a nondrug treatment is underway.
Insomnia seems to be caused by excessive metabolic activity in the brain's frontal cortex. For deep, refreshing sleep to occur, the frontal cortex has to rest, said Dr. Eric Nofzinger, a professor of psychiatry at the University of Pittsburgh.
Research on brain injuries has shown that cooling the brain reduces metabolic activity. Nofzinger and his colleagues decided to try the same concept on insomnia by designing a device that gently cools the frontal cortex during sleep.
In a pilot study of eight patients, five showed activity reductions in that brain area. Six of the eight reported they slept better. "They had increased slow-wave sleep, which is the deepest sleep," Nofzinger said.
The device is a cap worn over the forehead containing tubes that circulate cool water. Nofzinger has started a company to advance the research beyond these preliminary stages. (The study was small, and reports of better sleep could be a placebo effect.)
"Insomnia is widely prevalent," Nofzinger said. "And when you look at patient preferences, the majority would prefer a nonpharmaceutical therapy."
Bedtime and depression: When parents mandate early bedtimes for teenagers, they may help reduce the teens' risk for depression and suicidal thoughts, researchers from Columbia University found. The study of 15,000 teenagers included 1,143 who had depression and 2,038 who had experienced suicidal thoughts. Those with parental-mandated bedtimes of midnight or later were 25% more likely to suffer from depression and 20% more likely to have suicidal thoughts. The study supports the idea that inadequate sleep could lead to depression, said the lead author, James Gangwisch.
Happy, rested couples: The quality of a couple's sleep and relationship tend to follow the same trajectory, researchers said. On a day-to-day basis, a couple's relationship affects how well they sleep. And how well they sleep affects how the relationship functions the following day.
Researchers at the University of Arizona studied 29 heterosexual, co-sleeping couples who did not have children. Each person completed sleep diaries for seven days and was also asked to record, six times a day, the quality of interactions with his or her partner.
The study found that, for men, better sleep was linked to more positive ratings of relationship quality the next day. For women, negative interactions with a partner during the day led to poorer-quality sleep that night for both woman and man. The study's take-home message, lead investigator Brant Hasler said, is to settle conflicts before going to bed and avoid confrontational discussions on a day when one partner, or both, has had a bad night's sleep.