The 30% of working adults who routinely sleep less than six hours a night are four times more likely to suffer a stroke, says a new study.
The findings are the first to link insufficient sleep to stroke; they're also the first to apply even to adults who keep off extra pounds and have no other risk factors for stroke, says Megan Ruiter, lead author of the report. It will be presented Monday at the 26th annual meeting of the Associated Professional Sleep Societies in Boston.
"People know how important diet and exercise are in preventing strokes," says Ruiter, of the University of Alabama in Birmingham. "The public is less aware of the impact of insufficient amounts of sleep. Sleep is important - the body is stressed when it doesn't get the right amount."
The number of people who report eight or more hours of sleep a night has dropped from 38% in 2001 to 28%, says the National Sleep Foundation. A government study in May found 30% of working adults get six hours or less. Experts recommend seven to nine.
Previous research has shown that sustained partial sleep deprivation leads to modestly increased risk for cardiovascular events, such as heart attacks. But the new study focuses on people of normal weight, says Reena Pande, a cardiologist at Brigham and Women's Hospital in Boston.
"This makes you scratch your head and say it's not just the known factors," says Pande. "Less sleep is clearly linked to many harmful changes in the cardiovascular system."
The three-year study of 5,666 adults found that stroke risk was four times higher with less than six hours a night, vs. seven to eight. That applied to those whose body mass index (BMI) - a number based on height and weight - was normal and who were at low risk for sleep apnea.
Sleep study participants had no history of stroke, no symptoms and were not at high risk for sleep apnea. They self-reported sleep duration and any stroke symptoms at six-month intervals.
Strokes occur when blood to the brain is restricted or cut off. Stroke is still the fourth-leading cause of death in the USA. Smoking, being overweight and inactivity are key risk factors.