Skimping on Sleep Raises Heart Risk for Women
Study finds that too much shut-eye is bad, too
By Kathleen Doheny
But a new study suggests you're not doing your health any favors when you don't get enough shut-eye. You might be putting yourself at risk for a heart attack.
Researchers from Brigham and Women's Hospital in Boston found that women who sleep five or fewer hours have an 82 percent higher risk of heart attack than those who get the suggested eight hours, even after adjusting for age differences. Women who sleep six hours a night boost their heart attack risk by 30 percent.
But the researchers found that too much sleep isn't good, either. Those women who slept nine or more hours a night increased their heart disease risk by 57 percent.
The research, which evaluated some of the 121,700 women enrolled in the well-known Nurses' Health Study and followed them for 10 years, is published in the Jan. 27 issue of the Archives of Internal Medicine.
"I don't think the study is definitive per se, but suggestive," says Dr. Najib T. Ayas, an assistant professor of medicine at the University of British Columbia, who conducted the research while on faculty at Brigham and Women's Hospital.
So while Ayas cannot yet prove cause and effect, sleep deprivation and perhaps too much sleep should be considered unhealthy habits, he says.
Previous studies have found the same association between sleep deprivation and heart problems in men, Ayas says. What he and others think may be happening is that sleep deprivation can cause physiological changes -- such as boosting blood pressure -- that, in turn, up heart disease risk.
Only 37 percent of Americans get eight hours of sleep a night, and 31 percent get six or fewer, according to a recent poll from the National Sleep Foundation.
For the study, Ayas and his colleagues zeroed in on a subset group of the Nurses' Health Study -- 71,617 women ages 45 to 65 who did not have reported heart disease at the start of the study -- and followed them over 10 years to detect any association between sleep habits and heart attacks. Each had answered questions about sleep duration in 1986, 10 years after the study began.
When they adjusted not only for age but also for factors such as smoking and body mass index, the association was weaker but still present.
"I think this [study] is right on the money," says Dr. Virend Somers, a professor of medicine at the Mayo Clinic who is familiar with the study. "People are not sleeping enough and we are seeing the consequences."
What makes the study particularly impressive, he says, are the large numbers and the fact that the Nurses' Health Study is an established model that has yielded other important clues about cardiovascular risk, Somers says.
Even though no cause and effect is proven, Somers says women and men should take sleep deprivation seriously as a health risk.
"Eight hours [of sleep] would be optimal," Ayas says.
If you're really strapped for time? "Seven actually wasn't too bad. If you get seven hours, your relative risk of heart disease is about the same as [getting] eight hours," Ayas says.
To take a sleep test, visit the National Sleep Foundation. Also, the American Heart Association has a section devoted to women and heart health.
SOURCES: Najib T. Ayas, M.D., assistant professor of medicine, University of British Columbia, Vancouver; Virend Somers, M.D., Ph.D., professor of medicine, division of cardiology, Mayo Clinic, Rochester, Minn.; Jan. 27, 2003 Archives of Internal Medicine
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