A study published Monday found that people who sleep less tend to be fat.

　　Monday's study 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."

　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.