Stop those sleepless nights, now stop this and try to relax and avoid gaining weight, that's the message from a recently published study. This study shows that women who sleep 5 hours or less weigh more compared to those women who sleep 7 hours. This study was presented in the recently held American Thoracic Society International conference in May 2006.

This study showed that women who get only 5 hours or less of sleep per day were 32 percent more at risk of developing significant weight gain compared to women who sleep for 7 hours per day. Researchers defined significant weight increase as gain of 33 pounds or more. The study also showed that women who get 5 hours of sleep or less have 15 percent higher risk of becoming obese during the study period of 16 years, compared to women who sleep more. Women who had only 6 hours of sleep per day, stand at 12% increased risk of major weight gain and 6 percent increased risk of obesity when compared to women who regularly get 7 hours of sleep.

These results are drawn form a large study, comprising of a total of 68,183 middle-aged women, who were part of the Nurses health study. The study participants were required to give information about their sleeping hours and asked to report their weights every couple of years of years during the 16 years of the study. It was noted that at the beginning of the study women who had 5 hours or less of sleep on an average had 5.4 extra pounds in their body in comparison to women who had 7 hours of sleep on a regular basis. The lead investigator of the study, Dr. Sanjay Patel, says that this is the largest study of sleep habits and weight gain. He says that, this would be the first study to demonstrate that reduced sleeping is associated with increased risk of weight gain over a long period of time.

During the course of the study researchers tried to determine if the differences in dietary habits and physical activity had contributed to the weight gain in women who slept less. Researchers found that those women who are sleeping less are actually eating less compared to women who had good seven hours of sleep. The research questionnaire tracked the exercise and physical activity patterns of women who participated in the study, but the analysis did not show any statically significant variations in the physical activity patterns between women who slept less and women who slept more. The weight gain in women who slept five hours or less is not explained by eating more or having lesser physical activity. It is possible that women who are sleeping less may be moving around less outside the setting of planned exercise programs and may be thus burning lesser calories compared to women who sleep more. However researchers agree that more research is needed to determine what causes weight gain in women who sleep 5 hours or less.

Read more at: American Thoracic Society