Studies Show Why Lost Sleep Equals Gained Weight
(Washington, Reuters Health, 12/6/04)

Two new studies link lack of sleep to altered hormone balance, changes in eating habits and weight gain. In one study, Eve Van Cauter of the University of Chicago, and colleagues, measured the levels of leptin and ghrelin in 12 healthy, young men at the outset, after two nights of only four hours sleep and after two nights of ten hours sleep. The investigators found that sleeping just four hours a night was associated with an increase in ghrelin, a hormone that triggers appetite, and a reduction in leptin, which signals the brain that the body does not need more food. Furthermore, when the subjects were sleep-deprived, they chose more sweets and starches, leading scientists to speculate that the brain, which is fueled by glucose, may seek simple carbohydrates when suffering the distress of inadequate rest.

In a separate study, Dr. Emmanuel Mignot of Stanford University in California, and colleagues, examined 1,000 participants in the Wisconsin Sleep Cohort Study, recording the time the person had slept the previous night, their usual sleep habits and their leptin and ghrelin levels. The investigators found that subjects who slept less were more likely to have lower leptin levels and higher ghrelin levels and to be overweight. The scientists note that the disturbance of appetite regulation hormones by lack of sleep, coupled with the abundance of food in Western societies, may play a significant role in the rising incidence of obesity.