A new study suggests that sleeping more than eight hours and less than five hours per night increases one's risk to suffering from stroke.

Researchers at the Icahn School of Medicine of Mount Sinai Hospital in New York City looked at the data of 204,000 U.S. adults with ages 42 to 81 who were also diagnosed with high blood pressure. They categorized the participants depending on their average sleep hours per night: the long sleepers (more than eight hours), the short sleepers (5 to 6 hours), the insufficient sleepers (less than 5 hours), and the healthy sleepers (7 to 8 hours). The researchers also tracked for incidence of stroke.

After the nine-year follow-up period, the researchers found that 14 percent of the long sleepers suffered from a stroke, 11 percent on the insufficient sleepers, six percent on the short sleepers, and five percent on the healthy sleepers. After considering other factors such as health, age, sex, smoking and physical activity, the study concluded that the long sleepers are 74 percent risk of a stroke while the insufficient sleepers are at 80 percent, compared to the healthy sleepers.

"We were surprised, especially with the individuals reporting insufficient sleep, because most studies . . . have shown [only] a modest increase in the chances of suffering a stroke among those with short sleep duration," Dr. Oluwaseun Akinseye, study lead author and a resident in internal medicine at the Icahn School of Medicine of Mount Sinai Hospital in New York City, said to HealthDay News. 

"Our study showed much higher odds of a stroke, almost a twofold increase," he added.

According to the National Sleep Foundation, the sleep requirement varies per individual depending on the level of physical activity and lifestyle such as work schedule and stress. However, experts recommend sleep ranges depending on age. For instance, teens need 8 to 10 hours of sleep while younger adults need 7 to 9 hours to function at their best.

The study was presented on May 15 at the American Society of Hypertension's annual scientific meeting in New York City.