(dailyRx News) A simple, at-home treatment--a single light box and the over-the-counter drug melatonin--allows travelers to avoid jet lag by resetting their circadian body clock before crossing several time zones, according to research published in The Endocrine Society's Journal of Clinical Endocrinology and Metabolism.

This treatment can also help those with delayed sleep phase syndrome (DSPS), a persistent condition that results from a misalignment between a person's internal biological clock and the external social environment.

Both bright light and melatonin have successfully been used in laboratory and field settings to phase advance, or resetting the circadian clock earlier in time so that all the circadian rhythms of the body occur earlier, thereby helping people adapt to night shift work or to a new time zone following rapid transmeridian jet travel. Melatonin alone has been shown to synchronize the circadian clock of the blind to the 24-hour day.

"However, this is the first study to show that melatonin and bright light can both help to advance the circadian clock, and the combination of bright light and melatonin produces a larger phase advance than bright light alone," said senior author Charmane Eastman, Ph.D., Director of the Biological Rhythms Research Lab and Professor of the Behavioral Sciences Department at Rush University Medical Center in Chicago.

Dr. Eastman and colleagues at Rush's Biological Rhythms Research Lab studied 44 healthy adults--24 men and 19 women-- between the ages of 19 and 45. The participants were randomly divided into three groups and assigned one of three treatments--placebo, 0.5 mg of melatonin or 3.0 mg of melatonin.

Each participant was assigned a strict eight-hour sleep schedule that was similar to their typical sleep schedule. In addition, they had to remain in bed, in the dark, trying to sleep throughout the eight-hour scheduled sleep/dark period. On the seventh day, each person was given a baseline phase assessment, starting seven hours before and ending three hours after their beginning bedtime. They then slept in the lab and were awakened at their scheduled wake time. The participants continued on this sleep schedule through day 10 of the study.

Days 11 through 13 marked the treatment period of the study, during which the participants slept in the lab in individual, dark, temperature-controlled bedrooms. Each afternoon, each person received either 0.5 or 3.0 mg of melatonin or matching placebo. The study ended with a final phase assessment on day 14.

The researchers found that those given melatonin experienced significantly larger phase advances--the 0.5 mg group at 2.5 hours and the 3.0 mg group at 2.6 hours versus the placebo group at 1.7 hours. Moreover, the participants did not experience jet lag