Too much sleep could increase risk of early death, heart disease, study says

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Your room's temperature, caffeine and more can affect your sleep.

Research shows adults need seven to nine hours of sleep. However, some people stay in bed a little longer, which could come at a cost, according to a new report.

» RELATED: If you don't get enough sleep, your brain could start eating itself

Researchers from the American Heart Association recently conducted a study, published in the organization's journal, to evaluate the association between sleep duration and cardiovascular disease.

To do so, they reviewed 74 studies, which observed the quality and length of sleep of more than 3.3 million participants.

After analyzing the results, they found those who slept for 10 hours were 30 percent more likely to die prematurely, compared to those who slept for eight hours. Longer sleepers were also about 50 percent more likely to develop cardiovascular disease. Those who slept less than seven hours did not have a heighten risk of early mortality or heart disease.

“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