For people who are at risk for heart disease and diabetes, getting enough sleep may be especially important: Snoozing for less than 6 hours per night may increase their risk of premature death, a new study finds.
People in the study who had a high body mass index (BMI) and elevated cholesterol along with a few other risk factors for heart disease and diabetes — a combination called metabolic syndrome — and slept less than 6 hours per night were twice as likely to die of heart disease or stroke over a nearly 17-year period as people without the syndrome, the researchers found.
People with metabolic syndrome who slept at least 6 hours per night also had a higher risk of dying over the same time period than people without the syndrome, the scientists found. However, this risk was not as high as it was among the people who slept less than 6 hours per night and also had metabolic syndrome, according to the study. [5 Surprising Sleep Discoveries]
“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,” lead study author Julio Fernandez-Mendoza, an assistant professor of psychiatry at Penn State College of Medicine, said in a statement.
In the study, the researchers looked at 1,344 adults whose average age was 49. The researchers invited the people to sleep at a lab for one night, during which they observed how long the people slept. At the lab, the researchers also looked at whether the participants had metabolic syndrome. The syndrome was defined as a combination of a BMI higher than 30, and elevated levels of cholesterol, blood pressure, blood sugar and blood fats called triglycerides. Of all the people in the study, 39.2 percent had the syndrome.
Then, the researchers followed the people for nearly 17 years. During this time, 22 percent of the participants died, according to the study, which was published today (May 24) in the Journal of the American Heart Association.
The researchers looked at the relationship between metabolic syndrome, how long the participants slept at the study’s start and their risk of death during the 17 years. They found that the people with metabolic syndrome who slept at least 6 hours at the start of the study were 1.5 times more likely to die of cardiovascular disease or stroke than the people who did not have metabolic syndrome. [Where Is Heart Disease Risk the Highest and Lowest? (Maps)]
However, the people with metabolic syndrome who slept less than 6 hours at the start of the study were 2.1 times more likely to die of heart disease or stroke as the people without the syndrome.
Moreover, the people who slept less and also had metabolic syndrome were twice as likely to die from any cause during the study period as the people who did not have the syndrome. In comparison, the people with metabolic syndrome who slept 6 or more hours at the start of the study were 1.3 times more likely to die from any cause than the people without the syndrome.
Although the study shows a link between shorter sleep duration and mortality among people with metabolic syndrome, it does not prove that there is a causal relationship between the two, Fernandez-Mendoza said. In addition, more research is needed to understand the reasons for the link, he told Live Science.