Washington, June 11: Habitually sleeping less than six hours at night significantly elevates risk of stroke among middle-aged and older adults of normal weight at low risk for obstructive sleep apnea (OSA).
 These findings were based on a study of 5,666 people, who were followed for up to three years. The participants had no history of stroke, transient ischemic attack (when blood flow to a part of the brain stops briefly), stroke symptoms or high risk for OSA at the start of the study.
 Researchers from the University of Alabama, Birmingham, US, recorded the first stroke symptoms, along with demographic information, stroke risk factors, depression symptoms and various health behaviours.
 After adjusting for body-mass index (BMI or height to weight ratio), they found a strong link with daily sleep periods of less than six hours and a greater incidence of stroke symptoms for middle-age to older adults, even beyond other risk factors.
 The study found no link between short sleep periods and stroke symptoms among overweight and obese participants, according to an Alabama statement.
 "In employed middle-aged to older adults, relatively free of major risk factors for stroke such as obesity and sleep-disordered breathing, short sleep duration may exact its own negative influence on stroke development," said study co-author Megan Ruiter of Alabama.
 "We speculate that short sleep duration is a precursor to other traditional stroke risk factors, and once these traditional stroke risk factors are present, then perhaps they become stronger risk factors than sleep duration alone," added Ruiter.
 These findings were presented at SLEEP 2012, the 26th annual meeting of the Associated Professional Sleep Societies (APSS) in Boston, US.

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