Sleep loss may rev up appetite

Consistently getting a good night's sleep may be one of the answers to maintaining a healthy weight, if early research findings are correct.

The small study found that when healthy young men slept for only fours hours on two nights in a row, they showed dips in a hormone that suppresses appetite, coupled with increases in an appetite-stimulating hormone.

On top of that, the volunteers reported being more hungry after their sleep-deprived nights than after nights when they slept for 10 hours.

Though more research is needed, the new findings suggest that "if you do not run a sleep debt, you will be able to curb your appetite more easily and maintain or lose weight," study leader Dr. Eve Van Cauter, a professor of medicine at the University of Chicago, told Reuters Health.

Van Cauter and her colleagues report the findings in the Annals of Internal Medicine.

The two appetite-regulating hormones in question are leptin, which is released from fat cells and helps alert the brain that it's time to stop eating, and ghrelin, which is produced in the stomach and helps trigger hunger.

Van Cauter's team found that when the 12 men in their study slept for four hours on two consecutive nights, their levels of leptin were 18 percent lower and their levels of ghrelin were 28 percent higher than they were after two nights of spending 10 hours in bed.

When the men were asked to assess their appetites after sleep restriction, they showed a 24 percent increase in their "hunger ratings." And the foods they craved most were sweets, salty foods like chips and nuts, and starchy fare like bread and pasta.

The exact reasons for the hormonal changes associated with sleep deprivation are not yet known. According to Van Cauter, the mechanism may have to do with a small area in the brain where neurons respond to both eating and sleeping.

"We hypothesize that these neurons would be activated by sleep deprivation and stimulate ghrelin and decrease leptin," she explained.

Van Cauter and her colleagues point out that the rise in obesity in the U.S. has occurred in concert with a decline in time spent sleeping. Currently, less than one-quarter of young American adults sleep eight to nine hours per night - down from about 41 percent in 1960.

Whether these trends are related is unclear. There are ongoing studies, Van Cauter said, that are comparing weight changes over time among "short" and "long" sleepers.

In addition, studies in her team's lab are testing the hypothesis that sleep deprivation may thwart people's efforts to lose weight through dieting.

An editorial published with the report calls the findings "provocative," but adds that key questions remain. One of these is how well the results of a research experiment translate into the real world, according to Drs. Jeffrey S. Flier and Joel K. Elmquist of Beth Israel Deaconess Medical Center in Boston.