Getting too much sleep
may be a more serious sign of stroke
risk among older women than not getting enough sleep, according to a new
Researchers found that postmenopausal women who slept nine or more hours per
night were 70% more likely to suffer an ischemic stroke than women who slept an
average of seven hours a night.
An ischemic stroke is the most common type of stroke caused by a blockage in
an artery supplying blood to the brain.
In comparison, women who slept six hours or less per night had a 14% higher
risk of stroke compared to those who slept seven hours a night.
"What we don't know is whether the longer sleep time was the reason for
the increased risk or whether there was some other factor that both led people
to sleep more and was also a risk factor for stroke," researcher
Sylvia Wassertheil-Smoller, PhD of the Albert Einstein College of Medicine in
New York City says in a news release.
"In other words, this study does not mean that if you cut your hours of
sleep you would lower your stroke risk. It does mean that people who sleep
excessively long hours habitually (or who sleep less than six hours
habitually), should discuss this with their doctors and be sure to lower their
other risk factors for stroke, especially high blood
Sleep and Stroke Risk
In the study, published in Stroke: Journal of the American Heart
Association, researchers compared sleeping patterns and stroke risk among
93,175 women aged 50 to 79 years.
Although previous studies have provided mixed results on the link between
sleep and stroke risk, researchers say some didn't account for other factors
that may affect the risk of stroke, such as race, socioeconomic and lifestyle
factors, and depression symptoms .
In this study, researchers accounted for known stroke risk factors in
analyzing the link between sleep and stroke risk and found an increased risk
among those who slept more or less than seven hours per night.
There were 1,166 cases of ischemic stroke over the course of the study
(average follow-up of 7.5 years). The lowest risk for stroke was seen in women
who slept seven hours a night. The results showed that compared to women
sleeping seven hours a night, women who slept nine hours or more had a 70%
higher risk of stroke. Those who slept less than six hours per night had a 14%
higher risk of stroke. These findings took into account age, race,
socioeconomic status, depression , smoking , exercise , use of hormone therapy, and cardiovascular risk
factors such as past history or stroke or heart
attack , high blood pressure, and diabetes .
Although the degree of increased risk associated with getting too much sleep
was much higher than that associated with getting too little sleep, researchers
say nearly twice as many women reported getting less than six hours of sleep a
night (8.3%) compared with those who got nine hours or more (4.6%).
"The prevalence in women of having long sleep duration is much lower
than having sleep duration less than six hours. So the overall public health
impact of short sleep is probably larger than long sleep," researcher
Jiu-Chiuan Chen, MD, ScD., assistant professor of epidemiology at the
University of North Carolina's School of Public Health in Chapel Hill, says in
a news release. "This study provides additional evidence that habitual
sleep patterns in postmenopausal women could be important for determining the
risk of ischemic stroke."
Chen is careful to point out that these results apply only to postmenopausal
women and can't be applied to other groups.
By Jennifer Warner
Reviewed by Louise Chang
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