Sleep Loss and Weight Gain: Too Little
Sleep can Make you Fat

Several large studies suggest that sleep loss may precipitate weight gain. People who sleep less than seven hours a night tend to have a higher body mass index (BMI) than people who sleep more, according to data gathered by the US National Health and Nutrition Examination Survey.

Similarly, the US Nurses' Health Study, which tracked 68,000 women for 16 years, found that those who slept an average of five hours a night gained more weight during the study period than women who slept six hours, who in turn gained more than those who slept seven.

Two recent studies, one in Canada and the other in Germany, show that sleep duration and weight are linked in children too.

Eve Van Cauter, a University of Chicago sleep researcher, has spent 25 years doing research on the hormones that are affected by sleep. She says sleep deprivation activates a small part of the hypothalamus, the region of the brain that also is involved in appetite regulation.