MIAMI • Not getting enough sleep can double the chances of dying from heart disease or stroke, particularly in people with risk factors like diabetes, obesity, and high blood pressure and cholesterol, according to researchers in the United States.

The findings, published in the Journal Of The American Heart Association on Wednesday, were based on 1,344 adults randomly selected for a sleep study in Pennsylvania.

The participants' average age was 49 and 42 per cent of them were men. They were recruited to undergo a series of health screenings and spend one night in a sleep laboratory. Just over 39 per cent were found to have at least three risk factors for heart disease, which when clustered together are known as metabolic syndrome. These include a body mass index (BMI) higher than 30, and elevated cholesterol, blood pressure, and fasting blood sugar and triglyceride levels.

Participants were followed for an average of 16 years. About 22 per cent died during that period. Those with metabolic syndrome who slept less than six hours in the lab were 2.1 times more likely to die of heart disease or stroke than those who did not have at least three risk factors for heart disease.

Experts recommend adults get at least seven to eight hours of sleep per night.

Said lead author Julio Fernandez-Mendoza, an assistant professor at Penn State College of Medicine: "If you have several heart disease risk factors, taking care of your sleep and consulting with a clinician if you have insufficient sleep is important if you want to lower your risk of death from heart disease or stroke."

The study was described as the first to measure sleep duration in a laboratory setting, rather than relying on patient reports. Researchers said it was also the first to examine the impact of sleep duration on the risk of death in those with multiple heart disease risk factors. However, since the study was observational in nature, it stopped short of proving any cause and effect.