Is melatonin useful for jet lag?

Jet lag syndrome is an exogenous circadian rhythm sleep disorder, frequently reported in travelers who cross multiple time zones in a short period of time. Oral melatonin -a pineal neurohormone normally produced during darkness and responsible for regulating the body's circadian rhythms- has been used as treatment for this condition. Searching in Epistemonikos database, which is maintained by screening 30 databases, we identified four systematic reviews including 11 randomized trials. We combined the evidence using meta-analysis and generated a summary of findings table following the GRADE approach. We concluded the use of oral melatonin probably reduces symptoms associated with jet lag syndrome. It is not clear whether its use produces adverse effects; however, these would be probably mild.