Most of us know the risk factors for a stroke--smoking cigarettes, having a sedentary lifestyle, high blood pressure and/or high cholesterol, and the list goes on.

But now, new research suggests that not getting enough sleep could contribute to your risk of getting a stroke. A study presented at teh SLEEP 2012 conference showed that middle to older-aged people who get less than six hours of sleep a night have a higher stroke risk, even if they don't have a history of stroke and aren't overweight, and also don't have an increased risk for obstructive sleep apnea.

"These people sleeping less than six hours had a four times increased risk of experiencing these stroke symptoms compared to their normal weight counterparts that were getting seven to eight hours," study researcher Megan Ruiter, of the University of Alabama at Birmingham, told HuffPost.

Researchers studied 5,666 people over a three-year period for symptoms of stroke, risk factors for stroke, symptoms of depression and demographics. They found a link between getting less than six hours of sleep a night and stroke among normal-weight people, but they did not find a link in the overweight and obese study participants.

"I was expecting that we were going to see some sort of association, but I really wasn't expecting it in the normal weight folks and not the overweight folks," Ruiter said.

Ruiter explains that the lack of sleep contributes to the known risks of getting a stroke: increasing blood pressure, spurring inflammation and altering metabolic hormones. "Once these traditional stroke risk factors are present, then perhaps they become stronger risk factors than sleep duration alone," Ruiter said in a statement.

"A lot of people say that when things get stressful and schedules get tight sleep is the first thing to get sacrificed," Ruiter said. "It turns out that it's a lot more problematic than we previously realized."