Studies have found that sleep loss changes the circulating levels of metabolic hormones that regulate hunger. Sleep loss has been shown to lead to higher levels of gherlin, the hormone that triggers appetite, lower levels of leptin, a hormone produced by fat cells, which tells the body when it’s full or when it needs more calories, and an increased body mass index (BMI), a measure which scales weight to height. The result is that you feel hungrier and eat more than you really need.

A study by researchers at the University of Chicago found that the study subjects, a group of young men who slept only four hours a night for two nights, had a 28 percent increase in gherlin and an 18 percent decrease in leptin. In addition, the men craved calorie-dense, high-carbohydrate foods such as candy, cookies, chips and pasta when they were partially sleep deprived. The brain uses glucose for food and this may explain the men’s cravings for simple carbohydrates.

In the Wisconsin Sleep Cohort Study, which looked at 1000 people’s sleep habits and leptin and gherlin levels, researchers found that people who slept five hours or less per night had an average of 14.9 percent more gherlin and 15.5 percent lower leptin levels than people who slept eight hours a night. And the researchers found that in people who sleep less than eight hours a night, decreased sleep was proportional to increased BMI.

A study presented at the 2004 North American Association for the Study of Obesity found that people who sleep two to four hours a night are 73 percent more likely to be obese than people who are normal sleepers. Another study done at Case Western Reserve University in Cleveland found that women who sleep an average of five hours or less a night are 32 percent more likely to put on extra pounds and 15 percent more likely to be obese than women who get at least seven hours of sleep a night.

Bottom line, Americans sleep less and weigh more than they did 40 years ago. Obesity is a growing epidemic in the U.S. and in a January 2005 Archives of Internal Medicine editorial, two Northwestern University researchers stress the need to examine the role sleep plays in the growing obesity epidemic in this country as people tend to replace less sleep with more food. Sleep is beneficial for numerous reasons. It is restorative and healing and now here’s another very good reason to get your z’s – it might just help you keep those extra pounds off.