听美文故事记6级单词07-08（在线收听）

8.Stay Thin by Sleeping More?

A study published Monday found that people who sleep less tend to be fat, and experts said it's time find if more sleep will fight 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.

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 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.

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.