FRIDAY, May 5 (HealthDay News) -- Taking melatonin during non-typical sleep times significantly improves a person's ability to doze off, a new U.S. study finds.

The finding could be important for jet-lagged travelers, rotating or night-shift workers, and people with delayed sleep phase syndrome.

Melatonin -- naturally produced by the body in darkness -- helps the brain determine night and day in order to regulate sleep cycles and circadian timing. While millions of Americans take melatonin supplements to help them sleep better, research findings on the effectiveness of these supplements have been mixed.

In this study, researchers at Brigham and Women's Hospital and Harvard Medical School observed 21 men and 15 women, aged 18 to 30, with no significant history of medical, sleep or psychological disorders. The participants refrained from alcohol, caffeine, nicotine, illicit substances, and prescription and non-prescription drugs for three weeks before the start of the study.

For the first three days and nights, the volunteers were studied in the sleep lab to measure their normal sleep patterns and melatonin production.

"Participants were then kept on a 20-hour sleep-wake schedule, simulating a traveler crossing four time zones eastward every day," senior author Dr. Charles Czeisler, chief of the division of sleep medicine at Brigham and Women's Hospital, said in a prepared statement. "For the next three weeks, 30 minutes before each sleep episode, participants ingested either a placebo, 0.3 milligrams (mg), or 5.0 mg of pharmaceutical grade melatonin."

Reporting in the May 1 issue of Sleep, the team found that "sleep efficiency" when the body was not producing melatonin was 83 percent in the group taking the 5-milligram dose of melatonin, 84 percent among those taking the 0.3-milligram dose of melatonin, and 77 percent among those taking the placebo.

There were no significant differences in the three groups' sleep efficiency when melatonin was being produced in the body.

More information

The U.S. National Library of Medicine has more about melatonin.

-- Robert Preidt

SOURCE: Rush University Medical Center, news release, May 1, 2006

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