Melatonin stays steady with age, study finds

November 5, 1999
Web posted at: 1:02 p.m. EST (1802 GMT)

(CNN) -- Researchers have found melatonin levels do not decline with age, indicating the hormone has nothing to do with sleep disorders in older adults as previously believed.

For many older Americans, going to bed doesn't necessarily mean going to sleep. As we age, researchers say, our internal clocks change, and we don't sleep as deeply or as long as we did when we were younger.

Over the past two decades, small studies have concluded that levels of the hormone melatonin in the body decrease as we age, which researchers believed caused sleeping difficulties. But research in this week's American Journal of Medicine says that isn't true.

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"Our study indicates that healthy older people have indigenous melatonin production just as high on average as those of young men, and the message is: If it's not missing, don't replace it," said Dr. Charles Czeisler of Brigham and Woman's Hospital.

Melatonin is produced in the body in large quantities at night and is thought to control cycles of sleep and wakefulness.

Although health experts don't dispute melatonin's effect on sleep, they are concerned that healthy older people may be taking supplements of the hormone when they don't really need them.

Czeisler said there are many other environmental factors that may make sleeping difficult.

"They may keep the television or the radio on during the nighttime hours. When that occurs, that actually disturbs sleep, to have noise and light in the bedroom when you are trying to sleep," Czeisler said.

Sleeping in a room that's too cold or hot, going to bed at random times, drinking too much caffeine and smoking can all cause sleep disorders.

According to the study, taking aspirin, ibuprofen or beta blockers, which are used to treat heart disease, on a regular basis can reduce levels of melatonin. The authors say that may be the reason studies have previously shown lowered levels of the hormone in the elderly.

Researchers say there have been no large-scale studies done on side effects of taking melatonin supplements, but people should be cautious.

"There are some reports of people having depression becoming much worse after taking melatonin. There are reports of people developing hallucinations, in particular hallucinatory dreams, after taking melatonin," said Dr. Dan Oren of Yale University.

Melatonin is considered a food supplement, even though it is a human hormone. It is not regulated by the Food and Drug Administration and can be bought in any health food store. Researchers some people take 500 to 1,000 times more than their bodies would normal produce.