CHICAGO -- Here's some news that could keep middle-aged men awake nights: A lack of quality sleep may contribute to love handles and double chins.
Researchers at the University of Chicago found what appears to be a link between middle-age spread and men's sleep patterns as they get older.
They found that the quality of men's sleep decreases with age along with the body's production of growth hormone. The drop in growth hormone, in turn, is thought to lead to flab.
Now the researchers are working to see if new types of sleeping pills or hormone injections can slow signs of aging.
"We actually know that if we increase deep sleep, we can increase growth hormone," said Eve Van Cauter, a professor of medicine who led the study, published in Wednesday's Journal of the American Medical Association.
The study of beauty sleep was limited to healthy men, and it is not clear whether the findings apply to women.
Van Cauter and her team looked at sleep studies conducted on 149 men from 1985 to 1999. They found that by the time men reach age 45, they have nearly lost the ability to fall into deep sleep.
Men produce growth hormone primarily during that kind of sleep. In studies of the elderly, growth hormone deficiency has been connected to obesity and the loss of muscle mass.
The men involved in the sleep studies were of normal weight and ranged in age from 16 to 83. Researchers found that as the men moved into mid-life, from ages 35 to 50, their total amount of sleep remained fairly constant.
The amount of deep, or slow-wave, sleep, however, decreased from nearly 20 percent of a normal night's sleep for men 25 or younger to less than 5 percent for those over 35. Growth hormone secretion declined by nearly 75 percent.
The study also found that after age 50, men's total amount of sleep declined by about 27 minutes a decade. They awoke more frequently during the night and stayed awake longer.
REM sleep, associated with dreaming, also declined after age 50 to about 50 percent of a young man's level.
In an accompanying editorial, Dr. Marc R. Blackman of the Johns Hopkins University School of Medicine in Baltimore said researchers do not know for certain whether sleep quality influences the production of hormones or if the change in hormone levels itself is responsible for changes in sleep.
But Van Cauter said it is clear that more deep sleep produces more growth hormone.
The research could be used to examine whether growth hormone injections could slow signs of aging in men during early mid-life, she said. Currently, such therapy is used mostly for men 65 or older.
On the Net:
National Institute on Aging: http://www.nih.gov/nia/
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