May 24, 2006

May 24, 2006 (San Diego) — A new study presented here at the American Thoracic Society International Conference shows that middle-aged women who sleep 5 or fewer hours each night weigh an average of 2.5 kg more than those who sleep for at least 7 hours.

"Sleep deprivation has important effects on a patient's health, so clinicians should really ask their patients about their sleep habits," said study presenter Sanjay Patel, MD, an assistant professor of medicine at Case Western Reserve University in Cleveland. "Getting a good's night sleep has already been shown to have effects on diabetes and heart disease and now we see it affects weight as well."

Dr. Patel told Medscape that previous studies had already shown that women, men, and children who sleep less tend to weigh more than those who sleep more. But what had not been clear, he explained, is whether the loss of sleep caused the weight gain or vice versa.

The prospective database of the Nurses Health Study offered an opportunity to answer the question, Dr. Patel said. For the current analysis, the researchers studied 68,183 women, aged 40 to 65 years, who were first asked about their typical night's sleep in 1986. As part of routine questionnaires every 2 years for the next 16 years, they were also asked to report their weight.

In addition to weighing more at baseline, the women who slept less tended to gain more weight over time, Dr. Patel reported. After adjustment for age, those who slept for 5 or fewer hours per night gained 1.5 kg more during the next 10 years than those who slept at least 7 hours per night (P < .001).

After adjusting for other factors including smoking, snoring, caffeine and alcohol intake, medication, and menopausal status, those who slept for 5 or fewer hours per night gained 0.7 kg more during the next 10 years than those who slept at least 7 hours per night (P < .001).

Put another way, the researchers found that the women sleeping 5 or fewer hours per night were 32% more likely to experience major weight gain, defined as an increase of 33 lb or more, and 15% more likely to become obese during the 16-year study period than the women who slept at least 7 hours per night.

In addition, women who slept for 6 hours were 12% more likely to have major weight gain and 6% more likely to become obese compared with women who slept at least 7 hours per night.

One of the most surprising findings, Dr. Patel said, was that the women who slept less actually ate less as well.

"A study from the University of Chicago suggested that healthy people who get less sleep may eat more because of changes in levels of the hormones leptin and ghrelin. But this was not the case," Dr. Patel pointed out.

"We don't really understand why sleep deprivation predicts weight gain at this point, but it could be that because they are more tired, the women are less likely to exercise — become couch potatoes, if you will," Dr. Patel suggested. "Or, sleeping deprivation may cause changes in a person's basal metabolic rate."

Safwan Badr, MD, chief of pulmonary medicine at Wayne State University in Detroit, Michigan, said that like many other findings of the prospective Nurses Health Study, these results “should have a very important impact on medical practice.

“The practicing physician really needs to stress to her patient that getting a good night’s sleep is not just a luxury,” Dr. Badr told Medscape. “It’s a mandatory way to improve your health.”

ATS 2006 International Conference: Abstract C88. Presented May 23, 2006.

Reviewed by Margaret Clark, RN, RRT-NPS

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