Not getting enough sleep may put some people at risk for much more than being drowsy the next day, a new study says.

Middle-aged people with high blood pressure, Type 2 diabetes, heart disease or stroke could be at increased risk for cancer and early death if they get less than six hours of sleep a night, researchers reported Wednesday in the Journal of the American Heart Association.

Specifically, those with high blood pressure or diabetes who slept less than six hours had twice the risk of dying from heart disease or stroke compared with people who slept six or more hours. Sleep-deprived people with a history of heart disease or stroke had three times the increased risk of dying from cancer during the study that spanned three decades.

"Our study suggests that achieving normal sleep may be protective for some people with these health conditions and risks," the study's lead author Julio Fernandez-Mendoza said in a news release. He's an associate professor at Pennsylvania State College of Medicine and sleep psychologist at Penn State Health Milton S. Hershey Medical Center in Hershey.

But more research will be needed to determine whether increasing sleep through medical or behavioral therapies could reduce risk of early death, Fernandez-Mendoza said.

The study looked at more than 1,600 adults who were categorized into two groups. One had stage 2 high blood pressure or Type 2 diabetes. The other had heart disease or stroke.

Participants were studied in a sleep lab for one night between 1991 and 1998. Researchers then tracked their cause of death up to the end of 2016. In that period, 512 people died — one-third of them from heart disease or stroke and one-fourth from cancer.

Fernandez-Mendoza said better identification of people with specific sleep issues would potentially lead to better treatment.

"Short sleep duration should be included as a useful risk factor to predict the long-term outcomes of people with these health conditions," he said.