Could sleeping for more than eight hours a day raise your risk of suffering a stroke?

A new study found "long sleepers" are 46 percent more likely to have a stroke than those who slept between six and eight hours per night, the American Academy of Neurology reported. Individuals who went from sleeping from six hours per night to more than eight were found to be nearly four times more likely to have a stroke than those who got an average amount of sleep.

"Since people whose sleep patterns changed from short to long were nearly four times as likely to have a stroke, it's possible that this could serve as an early warning sign, suggesting the need for additional tests or for people to take steps known to reduce stroke risk, such as lowering blood pressure and cholesterol," said Alberto Ramos, of the University of Miami Miller School of Medicine and a member of the American Academy of Neurology.

To make their findings the researchers looked at 9,692 people with an average age of 62 who had never suffered a stroke. The participants were followed for an average of 9.5 years, during this time period 346 people in the study suffered a stroke.

Out of the 986 people who slept more than eight hours a night, 52 had a stroke, compared with 211 of the 6,684 who were average sleepers. The findings remained true even when other risk factors were taken into account, and a meta-analysis of past studies on sleep duration and stroke made the same connections.

"We don't know yet whether long sleep is a cause, consequence or early marker of ill health," said study author Yue Leng, M.Phil., of the University of Cambridge in the United Kingdom. "More research is needed to understand the relationship between long sleep and stroke."

The findings were published in a recent edition of the journal Neurology.