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Women Who Sleep Less Than 8 Hours Live Longer


How much sleep is too much or too little? For women, researchers at the University of California, San Diego say that to live longer, the optimal number is less than 8 hours, and that 5.0 to 6.5 hours is ideal.

Eight hours is too much sleep for women

In the new study, a team of investigators evaluated data originally collected between 1995 and 1999 from 459 women ranging in age from 50 to 81. That study had indicated women who slept 6.5 to 7.5 hours per night had the best survival rates.

Now, 14 years later, the researchers took another look at the original group of women, of whom 444 could be identified for evaluation purposes. Eight-six women had died.

According to the study’s lead scientists, Daniel F. Kripke, MD, professor emeritus of psychiatry at UC San Diego School of Medicine, “when sleep was measured objectively, the best survival was observed among women who slept 5 to 6.5 hours. Women who slept less than five hours a night or more than 6.5 hours were less likely to be alive at the 14-year follow-up.”

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The researchers also found that obstructive sleep apnea among older women did not predict an increased risk of death. Kripke noted that while sleep apnea may be associated with a greater risk of death among younger women, “it does not seem to carry a risk in the older age group, particularly for women.”

Countless studies have explored the optimal amount of sleep needed for various populations, from infants to the elderly. According to the National Sleep Foundation, there is no “magic number.” Visitors to the Foundation’s website will find that “not only do different age groups need different amounts of sleep, but sleep needs are also individual.”

That said, research shows that getting too little sleep is associated with many health concerns, including inhibited productivity, difficulty remembering and consolidating information, increased risk for motor vehicle accidents, increase in obesity, increased risk of diabetes and heart problems, and increased risk for psychiatric conditions. Some research also shows that too much sleep (generally considered more than 9 hours or more) is associated with an increased risk of illness and morbidity.

Are people losing sleep over worrying whether they are getting enough or too much sleep? According to Kripke, the results of this new study should provide some answers, at least for women who may worry about sleeping less than 8 hours. “This means that women who sleep as little as five to six-and-a-half hours have nothing to worry about since that amount of sleep is evidently consistent with excellent survival.”

National Sleep Foundation
University of California, San Diego