Review: oral melatonin reduces jet lag in air travellers

QUESTION: In people who travel by air across several time zones, can oral melatonin prevent or treat jet lag? DATA SOURCES: Studies were identified by searching the Cochrane Controlled Trials Register, Medline, EMBASE/Excerpta Medica, and PsycLIT with the terms melatonin, jet-lag, jet lag, aviation, air travel, and airtravel. SciSearch was also accessed, 2 journals (Aviation, Space and Environmental Medicine and Sleep from 1986-99) were hand searched, bibliographies of relevant studies were scanned, and authors of studies were contacted to identify further studies. Data and case reports of adverse effects of melatonin were also sought. STUDY SELECTION: Randomised controlled trials were selected if airline passengers, airline staff, or military personnel were studied; oral melatonin was compared with placebo or other medication; drugs were taken before, during, after, or a combination of times related to travel; and outcome data were provided. DATA EXTRACTION: Data were extracted on study quality and participants, timing and dose of melatonin and other study medications, flight information, and outcomes of subjective ratings of jet lag and its components (fatigue, daytime tiredness, onset of sleep at destination, onset and quality of sleep, psychological functioning, duration of return to normal, and measures indicating the phase of circadian rhythms). MAIN RESULTS: 10 trials met the inclusion criteria; 1 was not used in the analysis because the design was weak. All compared melatonin with placebo in adults. Melatonin was taken at the same clock time after arrival at the destination (close to bedtime at the destination). All trials were of treatment longer than 2 days; none examined shorter duration of treatment. All 9 trials individually showed a reduction in symptoms of jet lag. Meta-analysis of 5 trials showed that the weighted mean decrease in the global rating scale (range from 0, no jet lag, to 100, maximum jet lag) was 38 (95% CI 35 to 40) favouring melatonin. Studies comparing melatonin taken both before and after travel with melatonin taken after travel showed that the before and after treatment had no benefit over only taking melatonin after arrival. 1 study showed that jet lag was worse after eastward flights than westward flights. Both passengers and airline staff experienced benefits with melatonin. Daily doses between 0.5 and 5 mg were similarly effective, except that on the higher dose, study participants fell asleep more quickly and reported better sleep quality. Doses above 5 mg did not appear to be more effective. Slow release melatonin in a 2 mg dose was relatively ineffective. Few adverse effects occurred in healthy adults. CONCLUSION: Short term use of oral melatonin reduces jet lag in healthy adult air travellers and has few adverse effects.