Higher Death Risk for Short Sleepers with Metabolic Syndrome

For people with a common cluster of risk factors for heart disease and diabetes, getting less than six hours of sleep a night may double their risk of dying from heart disease or stroke, according to new research in Journal of the American Heart Association.

Researchers randomly selected 1,344 adults (average age 49 years, 42 percent male) who agreed to spend one night in a sleep laboratory as part of the Penn State Adult Cohort. Based on their test results, 39.2 percent of the participants were found to have at least three of the risk factors, that when clustered together are known as the metabolic syndrome. For this study, the cluster included body mass index (BMI) higher than 30 and elevated total cholesterol, blood pressure, fasting blood sugar and triglyceride levels.

During an average follow-up of 16.6 years, 22 percent of the participants died. Compared to people without the same cluster of risk factors, those with metabolic syndrome who clocked more than six hours of sleep time in the lab were about 1.49 times more likely to die of stroke during the 16.6-year follow-up period, while those who slept less than six hours in the lab were about 2.1 times more likely to die of heart disease or stroke. The short sleepers with metabolic syndrome were also 1.99 times more likely to die from any cause compared to those without metabolic syndrome.

The relationship was particularly striking because the researchers adjusted for sleep apnoea – sleep interrupted by pauses in breathing that is a known heart disease risk.

"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," said study lead author Julio Fernandez-Mendoza, PhD, an assistant professor at Penn 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.

The study is the first to measure sleep duration in the laboratory rather than rely on patient reports and the first to examine the impact of sleep duration on the risk of death in those with a common cluster of heart disease risk factors.

The researchers noted that this was an observational study so that the results cannot establish a cause-and-effect, only an association between short sleep and mortality in people with the metabolic syndrome.

"Future clinical trials are needed to determine whether lengthening sleep, in combination with lowering blood pressure and glucose, improves the prognosis of people with the metabolic syndrome," Fernandez-Mendoza pointed out.

Source: American Heart Association
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