Don’t sleep less than 6 hours or more than 9
A new U.S. study shows that postmenopausal women had increased risk of strokes if they sleep less than six hours a night or more than nine hours.
The research study was led by American epidemiologist Jiu-Chiuan Chen, an assistant professor at the University of North Carolina School of Public Health, in Chapel Hill, North Carolina.
Postmenopausal is the time-period after which the female reproductive system has stopped. In other words, it is considered the age at which all natural menstrual cycles of women have stopped.
Their results are published in the article “Sleep Duration and Risk of Ischemic Stroke in Postmenopausal Women” within the July 18, 2008 issue of the journal Stroke, a publication of the American Heart Association.
The study was conducted because only a small number of inconclusive studies have been conducted between cardiovascular disease and habitual sleep patterns.
The Chen study used 93,175 postmenopausal women, with ages that ranged from 50 to 79 years. The women participated in the Women’s Health Initiative Observational study.
For validity of its measurements, the researchers adjusted for various external factors such as socio-demographic and lifestyle conditions, depression, snoring, sleepiness symptoms, and cardiovascular diseases.
The researchers found that 8.3% of the female subjects reported sleeping less than five hours per night and 4.6% of the women reported sleeping over nine hours per night. The women were studied for, on average, 7.5 years. During this period, there were 1,166 reported cases of ischemic strokes (that is, a stroke that occurs because of a blockage in an artery).
What specifically did the researchers find? Who were at the most risk: those women that slept the least or slept the most?
The researchers found that women who slept more than nine yours per night on a regular basis had a 70% higher risk of having a stroke , when compared to women that slept about seven hours per night on a regular basis.
The study also found that postmenopausal women who slept less then six hours each night on a regular basis had a 14% increased risk of stroke than the women who regularly slept seven hours each night.
The authors concluded in the abstract to their paper, “Habitual sleep patterns are important neurobehavioral determinants of risk for ischemic stroke in postmenopausal women. The underlying neurobiology and mechanistic mediators for the putative adverse effect of long sleep ( 9 hours/night) need further elucidation.”
The authors of the study include Jiu-Chiuan Chen Robert L. Brunner, Hong Ren, Sylvia Wassertheil-Smoller, Joseph C. Larson, Douglas W. Levine, Matthew Allison, Michelle J. Naughton, and Marcia L. Stefanick.
They are associated with the Department of Epidemiology, University of North Carolina School of Public Health, Chapel Hill, North Carolina; Department of Family and Community Medicine, University of Nevada School of Medicine, Reno, Nevada; Fred Hutchinson Cancer Research Center, Seattle, Washington; Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, New York; Department of Psychology, University of North Carolina at Greensboro, Greensboro, North Carolina; Department of Family and Preventive Medicine, University of California San Diego, La Jolla, California; Wake Forest University School of Medicine, Winston-Salem, North Carolina; and Department of Medicine, Stanford University, Stanford, California.
