A new study has found that women who slept for 10 hours or more had a 63 percent increased risk of stroke compared to those who slept seven hours per night.
The risk estimates dropped to 55 percent when researchers controlled for body mass index, hypertension and history of diabetes.
The results for ischemic stroke were similar, although the power of the study to detect differences was limited for 10 or more hours of sleep, said researchers.
Beginning in 1986, 69,794 women without a history of stroke reported their sleep duration. During 20 years of follow-up, 2,303 cases of stroke were recorded. Median sleep duration was seven hours.
Researchers found the risk of stroke was lowest among women reporting seven hours of sleep per night. Those reporting sleep duration of six hours or less five hours per night were not at increased risk of stroke after adjustment for multiple confounders including lifestyle factors and depression.