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Posted by Ted ( on November 05, 1999 at 23:46:46:

Study Examines Age-Melatonin Link

.c The Associated Press

WASHINGTON (Nov. 5) - If you're getting old, the TV ads suggest, you need to pop some melatonin pills. After all, this hormone so important for a good night's sleep has long been thought to decrease with age.

Now a study funded by the National Institutes of Health suggests the dogma was wrong - that healthy older people produce just as much of the sleep hormone as young people.

''We never anticipated the result we found,'' said Dr. Charles Czeisler of Harvard Medical School, lead researcher of the study published Friday in the American Journal of Medicine. ''The conventional wisdom was that melatonin levels decline with age - some referred to it as the 'aging clock.'''

The new study, Czeisler said, means older Americans shouldn't believe those ads that urge popping over-the-counter melatonin supplements starting at age 40.

''There's no point in replacing something that's not missing,'' he said.

Melatonin is a natural hormone produced by the pineal gland deep in the brain. It is produced at high levels during a person's normal sleeping hours, and as the body starts to wake up, the melatonin levels drop. It's all part of the body's sleep-wake clock.

Some other studies do suggest melatonin can treat jet lag and certain other causes of insomnia. The study by Czeisler and co-author Jamie Zeitzer did not examine that.

Instead, it addressed whether just getting older means you have less melatonin, a serious question since so many older Americans do have sleeping problems - and many take melatonin supplements, said Dr. Andrew Monjan of the NIH's National Institute on Aging.

''We have the culture now of self-medication based upon what may be pseudo- or quasi-scientific claims,'' Monjan cautioned. This study ''clearly shows sleep problems in older people cannot be explained primarily on the basis of melatonin decreases with age.''

The study compared 34 healthy older men and women, ages 65 to 81, with 98 men ages 18 to 30. Unlike many previous studies, this one carefully controlled for anything that could artificially lower melatonin levels:

-Exposure to light, such as when people get up in the middle of the night and switch on the bathroom light, lowers melatonin.

-Varying sleep-wake times can make melatonin fluctuate.

-Drugs commonly used by the elderly, including beta blockers that treat high blood pressure and even aspirin, can lower melatonin.

Then the researchers brought the study volunteers into a sleep lab and carefully measured melatonin with their sleep-wake cycles - and found no difference between the young and old.

The finding is important because no one knows how safe the chronic use of melatonin supplements truly is, particularly in the large doses typically sold, Monjan said. Among other possibilities, some studies suggest high-dose melatonin could constrict blood vessels in the brain and risk stroke.

Melatonin supplements are typically sold in 3 milligram tablets, about 10 times higher than normal body levels, he said.

Some studies suggest much smaller doses of melatonin can fight jet lag, perhaps by helping the body reset its normal sleep-wake cycle, and that a small dose puts insomnia sufferers to sleep.

Larger studies are needed to prove that, said Czeisler. Some studies are under way.

But meanwhile, he complained, melatonin already is advertised as if its use is proved to help, because federal law allows dietary supplements to sell with far less proof of safety and effectiveness than most other over-the-counter medications.

Many older Americans do suffer insomnia, Monjan noted. But he urged that they try to cure their insomnia by finding the root cause of the sleep problem, often pain, depression, even sleep-depriving medications.

And those who take melatonin should tell their doctors, he said.

AP-NY-11-05-99 1408EST

Copyright 1999 The Associated Press. The information contained in the AP news report may not be published, broadcast, rewritten or otherwise distributed without the prior written authority of The Associated Press. All active hyperlinks have been inserted by AOL.

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