It sounds like the best diet plan of all time: sleep more, weigh less. It could be a reality, say researchers who have produced more evidence linking less sleep to obesity.
The findings, which appear in the Archives of Internal Medicine, don't say which came first--sleepy people or fat people. But study co-author Dr. Robert Vorona, an assistant professor of sleep medicine at Eastern Virginia Medical School, suspects that lack of sleep sets off hormonal changes that affect appetite. "It's very possible that, over the long haul, restrictions in sleep could dispose you to obesity," Vorona said.
He acknowledged that his theory is a bit odd, especially considering that people use more energy when they're awake. "It's counterintuitive that restricting sleep should lead to obesity, that sleeping more should make you more apt to lose weight," he said. "That doesn't sound like it makes sense."
Other researchers are on the same track, however. "There's a mounting body of evidence that suggests the systems that regulate sleep and appetite are linked," said Dr. Joseph Bass, a professor of medicine at Northwestern University Feinberg School of Medicine who studies sleep.
Vorona and his colleagues first became interested in the link between sleep and obesity after reading that insufficient sleep disrupts the body's endocrine system, which regulates hormone levels. Vorona said they decided to launch a study to see if weight was affected, too.
The researchers surveyed 1,001 people from southeastern Virginia about their sleep habits. They also checked where the subjects landed on the body-mass index (BMI) scale, which uses a mathematical formula to indicate whether a person is of normal weight, overweight, obese or severely obese. The typical subject was 48 years old and obese. The researchers found that people of normal weight got more sleep than their overweight and obese counterparts, by an average of 16 minutes per night, or 1.9 hours a week.
The research reflected previous studies in Japan that linked lack of sleep to obesity in children, Vorona said. Oddly, this latest study found that severely obese people actually got more sleep than other people. According to Vorona, this may be because their bodies are more likely to produce sleep-inducing chemicals.
The next step, Vorona said, is to launch more definitive studies that will closely track how much people sleep each day--instead of relying on their own memories--and examine changes in sleep and obesity levels over time. He hopes to "get funding to see if extending sleep really does help people lose weight effectively."
It's possible that further research into the link between
insufficient sleep and obesity may explain why shift workers--who
often don't get enough sleep--are more likely to develop diabetes,
said Bass, who wrote a commentary that accompanied Vorona's study.
"Sleep is a fascinating, enigmatic process," Bass said. "We kind of hand-wave at it as physicians, and maybe we shouldn't."
SOURCES: Robert Vorona, M.D., assistant professor, sleep medicine, Eastern Virginia Medical School, Norfolk; Joseph Bass, M.D., Ph.D., assistant professor, medicine, Northwestern University Feinberg School of Medicine, Chicago; Jan. 10, 2004, Archives of Internal Medicine
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