NEW YORK, Oct 11 (Reuters Health) - The normal flow of the body's circadian rhythm is guided in part by the light and dark of the day--a guide blind people cannot rely upon. But researchers have found that the health-food store staple melatonin may restore normal circadian rhythm in the blind.

Melatonin is a natural hormone produced at night. Because it is believed to help regulate sleep patterns, melatonin supplements have been touted as a treatment for sleep problems, jet lag, and even the effects of aging. While some studies have disputed these health claims, results of a small study suggest melatonin can correct the sleep disturbances that often plague blind people.

Dr. Robert L. Sack and his colleagues at Oregon Health Sciences University in Portland report their findings in the October 12th issue of The New England Journal of Medicine.

The body's "clock" runs on an approximately 24-hour day, with help from the light of day and dark of night. Because totally blind people have no "light cues," they often have disturbances in the circadian rhythm that lead to insomnia and daytime sleepiness.

Sack and his colleagues looked at whether daily doses of melatonin could correct sleep patterns among seven blind study participants. The investigators found that over 3 months, the hormone normalized circadian rhythm and improved sleep patterns for six of the seven.

The study participants started out on 10 milligrams of melatonin per day, but Sack's team found that in three patients, the dose could eventually be cut to just 0.5 milligrams while retaining the wanted effects.

These findings, according to Sack, are also relevant to sighted people with sleep problems. He told Reuters Health that about 30% of the population is sensitive to melatonin's sleep-inducing effects. In addition, he said, the supplement can help adjust the body clock in people suffering from jet lag, "morning lark and night owl sleep disorders," and winter depression.

This study also bolsters melatonin's potential as a real medical treatment, according to an editorial accompanying the report. The "hype" and claims of a miracle cure that have surrounded melatonin have done "a great disservice to a scientific field of real importance to human health," according to Dr Josephine Arendt of the University of Surrey in the UK.

But with research like the current study, she contends, "the true potential of melatonin" is becoming clear.

(From Reutershealth)