Educação pode mudar sua vida

THE FACTS: Most Americans relish the thought of sleeping late, and experts have traditionally recommended eight hours of rest each night. But a 2002 study found that getting more than seven hours of sleep each night was associated with a shorter life span. Several studies since then, including one this year by researchers at Brigham and Women’s Hospital in Boston, also found a link.

The 2002 study examined data on more than a million Americans over the age of 30 between 1982 and 1988. The risk of dying in that period climbed as subjects went above seven hours of sleep. Those who averaged eight hours a night, the study found, had a 12 percent increased chance of death. Other researchers have also found that life expectancy declines as sleep falls below seven hours, but not as steeply as it does with eight hours or more, said Dr. Jerome M. Siegel, of the University of California, Los Angeles. Most sleep experts are reluctant to draw conclusions because the findings are based on correlations, which cannot show cause and effect. People who sleep longer may have illnesses that cause fatigue and earlier death.

THE BOTTOM LINE: Averaging more than seven hours of sleep a night is associated with a shorter life span, though whether poor health or too much sleep accounts for the link is unclear.