Amount of nightly sleep linked to stroke

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BOSTON, June 12 (UPI) -- Routinely sleeping 6 hours or fewer a night significantly increases the risk of stroke symptoms among middle-age to older adults, U.S. researchers say.

Lead author Megan Ruiter of the University of Alabama at Birmingham said the study involved 5,666 normal-weight adults who were at low risk for obstructive sleep apnea. The study participants were tracked for as long as three years.

Ruiter and colleagues recorded the subjects' first stroke symptoms, along with demographic information, stroke risk factors, depression symptoms and various health behaviors.

After adjusting for body-mass index, the researchers found a strong association for middle-age to older adults with daily sleep periods of fewer than 6 hours and a greater incidence of stroke symptoms -- even beyond other risk factors. However, the study found no association between short sleep periods and stroke symptoms among overweight and obese participants.

"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," Ruiter said in a statement. "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."

The findings were presented at Sleep, the 26th annual meeting of the Associated Professional Sleep Societies in Boston.