“We found a significant association between deviations in sleep duration and both mortality and adverse cardiovascular outcomes,” the authors wrote. “The greater the divergence from the recommended durations of sleep, the greater the association for cardiovascular harm and mortality.”
The scientists do not know why longer sleepers are more at risk, but they noted sleeping too long and sleeping too little can both have effects on the body.
“Short sleep duration has been shown to increase levels of leptin and ghrelin, which leads to increased appetite ... and facilitates the development of obesity,” they said. “Depressive symptoms, low socioeconomic status, unemployment, and low physical activity are also associated with long sleep duration.”
Although this study advises people not to snooze excessively, others have suggested sleeping in may actually be good for your health.
A May study from Stockholm University's Stress Research Institute found that compensating for missed sleep on the weekends works and can lengthen your life. They said short weekday sleep was not a risk factor for mortality when combine with longer medium sleep.
» RELATED: Sleeping in on the weekends could help you live longer, study suggests