And while the relationship between unusual sleep patterns and mortality was strongest for cerebrovascular diseases, a link also was found between such sleep habits and death from any cause, said Adnan Qureshi, M.D., UB assistant professor of neurosurgery and lead author of the study. The research, conducted at UB's Toshiba Stroke Research Center in the School of Medicine and Biomedicine Sciences, was presented by Qureshi recently at the 27th International Stroke Conference in San Antonio.
The findings do not suggest that people who regularly sleep more than normal could cut their risk by spending less time under the covers, however. What they indicate, Qureshi said, is the possible existence of an underlying sleep disorder that is hazardous to health.
"The mechanism behind this association between sleep patterns and mortality is not clear," he stated, "but we hypothesize it may signal there are other conditions that need to be addressed, such as sleep apnea."
People with sleep apnea stop breathing briefly and repeatedly during the night. They wake frequently gasping for breath, which robs them of restful sleep and can lead to drowsiness during the day. The condition is recognized as a contributor to heart disease and stroke.
Earlier research conducted by Qureshi with 1,348 adults who participated in a stroke-screening program in Buffalo showed that those who regularly slept more than eight hours a night had 9 percent more strokes than those who slept less. Persons who were regularly sleepy during the day showed a 10 percent increase in stroke.
The current study involved a national cohort of 7,844 adults who participated in the first National Health and Nutritional Examination Survey and its 10-year follow-up.
Participants in the initial survey, conducted in a random sample of the U.S. population, provided extensive information on health status and lifestyle habits, including sleep patterns. The follow-up study assessed changes in health since the initial survey.
After adjusting for several conditions that could influence a participant's risk of death from most chronic diseases, results showed that both those who slept more than eight hours a day and those who were regularly sleepy during the day had a 50 percent increased risk of dying compared to participants without those habits. More telling, those persons were nearly three times as likely to have died from stroke than persons with normal sleep patterns, results showed.
"The message here is that a person's unusual sleep habits should raise a 'red flag,'" Qureshi said. "Something is happening in the lives of these people that is increasing their risk of death, especially from stroke.
"It could be related to an underlying sleep disorder. There is a higher prevalence of hypertension and other risk factors in patients with sleep disorders such as sleep apnea. Or their unusual sleep patterns may be a result of underlying social or psychological factors, such as stress or depression. It's something both patients and their doctors should pay attention to," Qureshi said.
Other faculty from the UB Department of Neurosurgery and UB's Toshiba Stroke Research Center involved in the study were M. Fareed K. Suri, M.D, Lee R. Guterman, M.D., Ph.D., and L. Nelson Hopkins, M.D., department chair.