Adults who regularly get less than six hours of sleep a night quadruple their risk of suffering a stroke, US scientists said.
Researchers from the University of Alabama-Birmingham studied more than 5,600 people aged 45 and over for up to three years and found a four times greater risk of stroke in participants who slept for fewer than six hours a night, compared to those who got seven to eight hours.
Factors that could potentially explain the increase -- including hypertension, high cholesterol, sleep disordered breathing and being overweight or obese -- were taken into account, the researchers said.
Lead author Dr. Megan Ruiter, who presented the research at the SLEEP 2012 conference in Boston on Monday, said, "Despite controlling for other known stroke risk factors, we still found the association between sleeping less than six hours and reporting stroke symptoms, like sudden body weakness or numbness or deficits in vision."
Dr. Susan Harding, a sleep specialist from the university's Sleep/Wake Disorders Center, added, "Short sleep duration is already associated with cardiovascular death and other cardiovascular-related events. What is different with this study is that it specifically looked at people who are at a normal weight, which means they are less likely to have diabetes -- which is a stroke risk factor -- and found they are still at increased risk of stroke symptoms."
Ruiter noted that sleep duration was self-reported by participants -- making it a limitation of the study -- and said further research was needed.