Melatonin and jet lag: what the studies really say

Melatonin is secreted by the body in the evening and at night. Taken as a tablet, it can both help you fall asleep and help the clock shift, depending on when it is taken.

A Cochrane review concluded that melatonin reduces jet lag symptoms in travelers crossing at least five time zones, especially eastward, when taken at bedtime at the destination. Low doses seemed as effective as higher ones for the time shift, with higher doses acting slightly more on falling asleep.

In France, the health agency ANSES advised certain people to avoid melatonin supplements, notably pregnant or breastfeeding women, children and adolescents, and people with inflammatory or autoimmune diseases. Interactions with some medications are possible, and drowsiness can impair driving.

Timing matters as much as the dose: taken at the wrong time, melatonin can shift the clock the wrong way.