Melatonin for jet lag
Melatonin is one of the few substances where the clinical evidence for jet lag specifically is both reasonably strong and consistently surprising in its implications: the effective dose is far lower than what most over-the-counter products sell, and the timing matters far more than the amount.
What the research actually shows on dosage
A Cochrane systematic review of jet lag trials found that melatonin at doses between 0.5 mg and 5 mg was consistently effective for reducing jet lag symptoms after long-haul flights. The counterintuitive finding: there was no meaningful dose-response above approximately 0.5 mg. A 0.5 mg dose shifted circadian timing about as effectively as a 5 mg or 10 mg dose. Higher doses added sedation and morning grogginess without improving the circadian reset, which is the mechanism that matters for jet lag.
Timing over dosage
The evidence consistently points to timing as the primary lever. For eastward travel, melatonin taken at the destination bedtime on the day of arrival and for the following 2-4 nights is the protocol supported by most trial data. For westward travel the evidence is weaker, but taking melatonin at the destination bedtime is still the standard recommendation. Taking it too early in the local afternoon can shift the clock the wrong way.
Why the short half-life is an asset here
Melatonin's 20-45 minute half-life is well suited to jet lag use: it provides the circadian signal without lingering into the morning, when residual melatonin would suppress the morning cortisol rise that anchors the new time zone. This is also why slow-release formulations are not clearly advantageous for jet lag specifically; the sharp, timed signal is what produces the circadian shift, not sustained levels through the night.
Not medical advice
This content is for informational purposes only. It is not a substitute for advice from a qualified healthcare professional and should not be used to make medication, dosing, or health decisions.