Aug. 2, 2010 -- People who sleep for less than seven hours a day, including naps, are at a higher risk of cardiovascular disease. Sleeping fewer than five hours a day, including naps, more than doubles the risk of chest pain, heart attack, or stroke, according to a study conducted by researchers at West Virginia University’s (WVU) faculty of medicine.
Most at risk were people over age 60 who slept for five hours or less per night. Their risk of developing cardiovascular disease was more than three times that of people who slept for seven hours.
The study, published in the journal Sleep, found that sleeping for more than seven hours also increased the risk of cardiovascular disease. Study participants who slept for nine hours or more were one-and-a half times more likely to develop cardiovascular disease than people who slept seven hours.
Researchers led by Anoop Shankar, MD, PhD, associate professor at WVU’s department of community medicine, analyzed data from more than 30,000 adults. The authors of the study were unable to determine the causal relationship between how long someone sleeps and their risk of cardiovascular disease. However, they noted that the duration of sleep affects endocrine and metabolic functions. Lack of sleep can lead to high blood pressure, impaired glucose tolerance, and reduced insulin sensitivity, which can all lead to hardening of the arteries.
Catch Up on Sleep
A separate study, also published in Sleep, showed that occasional “recovery sleep” can help people who routinely skimp on sleep. In this study, 142 adults whose sleep was severely restricted for five days -- as it can be for many people during the work week -- had reaction times that were slower and had more trouble focusing.
However, having an extra hour or two of sleep in the morning after a period where sleep was restricted to four hours a night resulted in a major improvement in symptoms of sleep deprivation. The improvements were seen after just one night of recovery sleep.
"The additional hour or two of sleep in the morning after a period of chronic partial sleep loss has genuine benefits for continued recovery of behavioral alertness," says David Dinges, head of the sleep and chronobiology unit at the University of Pennsylvania’s School of Medicine, who led the study. Catching up on sleep on the weekend can be good for you. But be warned: For severe sleep deprivation, an extra 10 hours of sleep may not be enough, according to the study.
Performance and alertness deteriorated profoundly when the five nights of restricted sleep were followed by a night of either no sleep or only two hours of sleep, the study also showed. So partying all night after a week of little sleep is not such a good idea.