Middle-aged adults with high blood pressure, Type 2 diabetes, heart disease or stroke could be at high risk for cancer and early death when sleeping less than six hours per day, according to new research published in the Journal of the American Heart Association, the open access journal of the American Heart Association.

"Our study suggests that achieving normal sleep may be protective for some people with these health conditions and risks," said lead study author Julio Fernandez-Mendoza, Ph.D., associate professor at Pennsylvania State College of Medicine and sleep psychologist at the Sleep Research & Treatment Center of the Penn State Health Milton S. Hershey Medical Center in Hershey, Pennsylvania. "However, further research is needed to examine whether improving and increasing sleep through medical or behavioral therapies can reduce risk of early death."

Researchers analyzed data of more than 1,600 adults (20 to 74 years old, more than half women) from the Penn State Adult Cohort who were categorized into two groups as having stage 2 high blood pressure or Type 2 diabetes and having heart disease or stroke. Participants were studied in the sleep laboratory (1991-1998) for one night and then researchers tracked their cause of death up to the end of 2016.

Researchers found:

Of the 512 people who passed away, one-third died of heart disease or stroke and one-fourth died due to cancer.

People who had high blood pressure or diabetes and slept less than 6 hours had twice the increased risk of dying from heart disease or stroke.

People who had heart disease or stroke and slept less than 6 hours had three times the increased risk of dying from cancer.

The increased risk of early death for people with high blood pressure or diabetes was negligible if they slept for more than 6 hours.

"Short sleep duration should be included as a useful risk factor to predict the long-term outcomes of people with these health conditions and as a target of primary and specialized clinical practices," Fernandez-Mendoza said. "I'd like to see policy changes so that sleep consultations and sleep studies become a more integral part of our healthcare systems. Better identification of people with specific sleep issues would potentially lead to improved prevention, more complete treatment approaches, better long-term outcomes and less healthcare usage."

Sleep duration in this study was based on observing one night's sleep, which may be affected by the first-night effect where participants sleep significantly worse the first night in a lab compared to other consecutive nights, which is the type of sleep study routinely used in clinical practices.

According to the American Heart Association, roughly 45% of the United States population has stage 2 high blood pressure and/or Type 2 diabetes, while another 14% have heart disease or stroke.