SEATTLE (Reuters Health) - Women who regularly don't get enough sleep are more likely to suffer from heart disease, according to the results of a study.

But women who slept for more than 9 hours also had an increased risk of heart attack, Dr. Najib Ayas of Brigham and Women's Hospital in Boston, Massachusetts, reported here Wednesday at the Associated Professional Sleep Societies' annual meeting.

"According to a National Sleep Foundation poll in 2001, one third of the population, or 37%, obtain at least 8 hours of sleep at night," Ayas told conference attendees. "Thirty-one percent report getting less than 6 hours per night."

Beyond daytime drowsiness, sleep deprivation has also been linked to poor health, noted Ayas. He and his colleagues set out to investigate whether sleep deprivation had any long-term consequences, in particular an increased risk of heart disease.

The investigators studied 71,617 women enrolled in the Nurses' Health Study who were aged 45 to 65 and had no reported heart disease. The women reported how long they slept nightly in 1986, after which the researchers followed them for 10 years.

A total of 934 heart attacks and other coronary events, both fatal and nonfatal, occurred among the women during the study period. Women who reported sleeping 5, 6 or 9 or more hours of sleep a night were at greater risk of having a heart attack or other event, the team found.

Using women who got 8 hours of sleep as a reference point, the researchers found that women who slept less than 5 hours a night had an 82% greater risk of heart disease. Women who slept 6 hours had a 30% increased risk, and those who slept 9 hours or longer showed a 57% increased risk.

One major advantage to the study, Ayas noted, is that he and his colleagues had information on study participants' lifestyles, including factors that can boost heart disease risk such as "diabetes, snoring, hypertension, depression, shift work, alcohol use and smoking and use of aspirin."

After adjusting for these factors, the short- and long-sleeping women's risk was lowered, but was still greater than for women who slept 8 hours. Women who slept 5 hours or less a night had a 39% increased risk of heart disease, while those who slept 9 hours or longer had a 37% increased risk.

Ayas acknowledged that his study had several limitations, including the fact that the women reported their own sleep times and only gave information for 1986. Also, he said, the results aren't applicable to men.

"Nevertheless, our results did suggest that both short- and long-term self-reported sleep durations are independently associated with a modestly increased risk of coronary events in women," Ayas concluded.

Reference Source 89

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