The symptoms of jet lag cause distress to an increasing number of travelers. Potentially they may impair sleep, mood and cognitive performance. Critically timed exposure to bright light and melatonin administration can help to reduce symptoms. Bright light is one of the most powerful synchronizers of human rhythms and melatonin serves as a "dark pulse" helping to induce nighttime behaviors. Thus, enhancing day and night signals to the brain, appropriate to the environmental light/dark cycle of the new time zone, can serve to reestablish adaptive timing relationships between the body's internal biological rhythms and the external environment, and thereby reduce the symptoms of jet lag. Specific recommendations using bright light and melatonin for eastward and westward travel before and after departure are provided for time zone changes of up to 6, 7-9 and 10 or more hours.