Women who sleep 5 hours or less per night weigh more on average than those who sleep 7 hours, according to a study presented at the American Thoracic Society International Conference.
The study found that women who slept for 5 hours per night were 32% more likely to experience major weight gain (defined as an increase of 33 pounds or more) and 15% more likely to become obese over the course of the 16-year study compared with women who slept 7 hours. 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 7 hours a night.
The study included 68,183 middle-aged women who were enrolled in the Nurses Health Study. They were asked in 1986 about their typical night's sleep, and were then asked to report their weight every 2 years for 16 years.
On average, women who slept 5 hours or less per night weighed 5.4 pounds more at the beginning of the study than those sleeping 7 hours and gained an additional 1.6 pounds more over the next 10 years.
"That may not sound like much, but it is an average amount--some women gained much more than that, and even a small difference in weight can increase a person's risk of health problems such as diabetes and hypertension," said lead researcher Sanjay Patel, M.D., Assistant Professor of Medicine at Case Western Reserve University in Cleveland, OH.
Dr. Patel noted that this is by far the largest study to track the effect of sleep habits on weight gain over time. "There have been a number of studies that have shown that at one point in time, people who sleep less weigh more, but this is one of the first studies to show reduced sleep increases the risk of gaining weight over time."