June 11 (HealthDay News) -- Two new studies suggest that chronic poor sleep can actually boost your odds for dying prematurely, while another study finds that more than half of older Americans aren't getting the recommended eight hours of slumber.
All three studies were presented this week at the Associated Professional Sleep Societies annual meeting, in Seattle.
The first study, from a consortium of researchers, found that death rates were higher among people who had more "fragmented" sleep, meaning they had more transitions between stages of sleep per hour. Those stages were: wake-to-non-rapid-eye-movement (NREM); NREM-to-wake; NREM-to-REM; REM-to-NREM; and REM-to-wake.
Although few studies have looked at fragmentation specifically, other studies have found that sleep-disordered breathing, which can contribute to sleep fragmentation, can increase the risk for early death.
Over the eight years of the study, participants with more fragmented sleep had a 5 percent increased chance of dying.
The wake-to-non-REM and non-REM-to-wake transitions were most closely linked to the higher risk of dying. The odds of dying were actually less with the other transition types.
"We're learning more about how slow-wave sleep has effects on the body, helping people relax, lowering heart rate, lowering blood pressure," said Dr. Carl Boethel, an assistant professor of internal medicine at Texas A&M Health Science Center College of Medicine and associate director of the sleep disorders clinic at Scott & White. "We think those things are very important."
But, pointed out Dr. Nicholas Rummo, director of the Center for Sleep Medicine at Northern Westchester Hospital Center in Mount Kisco, N.Y., it's impossible to tell what conditions are underlying these sleep deficiencies, conditions that ultimately may be "at fault."
"I don't think one should get too excited about it because 5 percent is not a big change as far as epidemiological studies are concerned," Rummo said. "Sicker people, for whatever reason, will have disturbed sleep. It's a chicken-and-egg argument. Is it the sleep itself that is making people die or some underlying factor that sleep is reflecting? Sleep is a very sensitive indicator as to how well we are."
The second study found that men with insomnia who sleep fewer than six hours each night are also at an increased risk of dying compared with people who sleep longer.
Less sleep has previously been linked with hypertension and other risk factors for cardiovascular disease.
Almost 2,000 men and women were followed for more than a decade, after initially being examined in a sleep laboratory.
Men with insomnia who slept five or fewer hours a night had a more than fourfold higher risk of dying during the study period; men with insomnia who slept five to six hours a night had a fivefold increased risk, compared with those sleeping a relatively luxurious six or more hours.
Women with insomnia also had a higher mortality risk, but it was not significant, stated the authors, from the Penn State College of Medicine, in Hershey, Pa.
"This confirms something we've been concerned about for a long time -- that insomnia probably does cause health problems," Boethel said. "Men are less likely to complain about insomnia. They are also more likely to be shift workers where they're less likely to get sleep, especially if they're working rotating schedules. It would be interesting to see in the study how many were actually shift workers."
A final study, based on a survey of more than 1,500 adults age 60 and over, concluded that fewer than half of older Americans are getting enough sleep.
More than half of the participants, 55 percent, reported that they had slept an average of seven hours or less each night over the last month. Almost two-thirds (61 percent) said it took them 15 minutes or less to fall asleep, reported researchers from the University of Virginia, in Charlottesville.
Those with symptoms of depression, who were more educated, were unmarried, were black and earned more money seemed to experience poorer sleep and reported feeling less alert during the day.
"Insomnia is always very difficult to treat," Boethel said. "We do have medications, but what seems to work the best is cognitive behavioral therapy, which is working with patients to try to recognize what's keeping them awake."
As for how much sleep is enough, that varies from person to person, Boethel said.
"But the biggest population-based study found that people who sleep six to eight hours live the longest," he said.
SOURCES: Nicholas Rummo, M.D., director, Center for Sleep Medicine, Northern Westchester Hospital Center, Mount Kisco, N.Y.; Carl Boethel, M.D., assistant professor, internal medicine, Texas A&M Health Science Center College of Medicine, section chief, pulmonary rehabilitation, and associate director, sleep disorders clinic, Scott & White; June 10, 2009, presentations, Associated Professional Sleep Societies annual meeting, Seattle