2004-12-14
I'm Gwen Outen with the VOA Special English Health Report.
There are new findings that not enough sleep may cause people to
gain weight. Researchers say a lack of sleep can produce hormonal
changes that increase feelings of hunger.
In one study, researchers in the United States examined
information on more than one thousand people. The people had taken
part in a long-term study of sleep disorders.
Some people slept less than five hours a night. They had fifteen
percent higher blood levels of a hormone called ghrelin than people
who slept eight hours. And they had fifteen percent less of the
hormone leptin. Experts say ghrelin helps make people feel hungry;
leptin makes you feel full.
The scientists say these hormonal changes may be a cause of
obesity in Western societies. They note the combination that sleep
restriction is common and food is widely available.
The results were not affected by how much people exercised.
People who are awake longer have more time to burn energy. But the
researchers say loss of sleep may increase hunger especially for
high-calorie foods, so people gain weight.
Researchers from Stanford University in California and the
University of Wisconsin did the study. They found that the best
amount of sleep for weight control is seven-point-seven hours a
night.
The Public Library of Science published the findings in its
journal Medicine. Internet users can read the full study, free of
charge, at plos.org.
Researchers at the University of Chicago did a smaller study,
reported in the Annals of Internal Medicine. They found that people
who slept just four hours a night for two nights had an eighteen
percent reduction in leptin. And they had a twenty-eight percent
increase in ghrelin. The young men in that study also appeared to
want more sweet and starchy foods.
Researchers from Columbia University in New York did a third
study. They reported the findings at a meeting of the North American
Association for the Study of Obesity.
They found that people who got less than four hours of sleep a
night were seventy-three percent more likely to be overweight. This
was compared to people with seven to nine hours of sleep. The
researchers say that for survival, the body may be designed to store
more fat during times with less sleep.
This VOA Special English Health Report was written by Cynthia
Kirk. I'm Gwen Outen.