Can sleeping help make you thin?

CHICAGO (Reuters) -- A study published on Monday found that people who sleep less tend to be fat, and experts said it's time to find if more sleep fights obesity.

"We've put so much emphasis on diet and exercise that we've failed to recognize the value of good sleep," said Fred Turek, a physician at Northwestern University.

"In fact society emphasizes just the opposite," in work places where billed hours are crucial and long work days are common, he added.

Monday's study from Eastern Virginia Medical School in Norfolk covered 1,000 people and found that total sleep time decreased as body mass index -- a measure of weight based on height -- increased.

Men slept an average of 27 minutes less than women and overweight and obese patients slept less than patients with normal weights, it said.

In general the fatter subjects slept about 1.8 hours a week less than those with normal weights.

"Americans experience insufficient sleep and corpulent bodies. Clinicians are aware of the burden of obesity on patients," the study said.

"Our findings suggest that major extensions of sleep time may not be necessary, as an extra 20 minutes of sleep per night seems to be associated with a lower body mass index," it added.

"We caution that this study does not establish a cause-and-effect relationship between restricted sleep and obesity, (but) investigations demonstrating success in weight loss via extensions of sleep would help greatly to establish such a relationship."

The study was published in the Archives of Internal Medicine, along with an editorial by Turek and Northwestern colleague Joseph Bass commenting on it and related research.

In an interview with Reuters, Turek said some studies have shown sleep deprivation causes declines in an appetite suppressing protein hormone called leptin, and increases in another hormone that causes a craving for food.

In addition neuropeptides in the brain governing sleep and obesity appear to overlap, he said.

"It is now critical to determine the importance of lack of sufficient sleep during the early formative years in putting our youth on a trajectory toward obesity ... a trajectory that could be altered if sleep loss is indeed playing a role in this epidemic," the editorial said.

Obesity has been rising dramatically in developed countries and reached epidemic levels in the United States, it added, leading to a variety of health problems.

"In recent years, a new and unexpected 'obesity villain' has emerged, first from laboratory studies and now ... in population-based studies: insufficient sleep," it said.

"However, while there is a growing awareness among some sleep, metabolic, cardiovascular, and diabetes researchers that insufficient sleep could be leading to a cascade of disorders, few in the general medicine profession or in the lay public have yet made the connection," it added.