Few studies have been done on melatonin's safety, side effects, interactions with other drugs, and long-term effects. We don't know how much to take, when to take it, whether it's effectiveness varies for different groups of people, or whether the listed doses are accurate. Worsened fatigue, depression, constriction of the arteries to the heart, and possible effects on fertility have been reported. Worse, melatonin researchers have often administered the substance to subjects during the day. Thus, the value of melatonin in improving disturbed sleep has not been systematically evaluated.
Light resets the body's rhythms or biological clock in a more powerful way than melatonin.
This is why researchers have counseled travelers crossing time zones to use sunlight or artificial bright light to help their bodies adapt. The good news, according to the National Sleep Foundation brochure, is that jet lag and insomnia are both treatable. If not, sufferers should see their doctor. Resources are included in the brochure. Dr. Roth stresses.