Melatonin is evidence-backed for shifting the timing of the body's internal clock (e.g., speeding circadian re-entrainment — see Jet Lag Travel Protocol (Pre/In/Post-Flight)), rather than as a general-purpose sleep-inducing sedative.
Regulatory caveat: in the US, melatonin is sold as an unregulated dietary supplement, not an FDA-regulated drug. Independent testing has found labeled-vs-actual dose content ranging from under 100% to over 400% of what the label states, meaning two bottles claiming the same dose can deliver wildly different amounts.
Practical implication: athletes subject to anti-doping testing are advised to use only NSF Certified for Sport (or equivalent third-party certified) melatonin products, to avoid contamination or mislabeled banned substances.
Because melatonin is sold as an unregulated supplement in the US, actual content can range from under 100% to over 400% of what the label states. For anyone subject to anti-doping testing, Dr. Mah recommends choosing an NSF Sports–certified product specifically, since certification verifies the product contains what it claims and is free of banned substances — melatonin itself remains a reasonable tool for advancing sleep timing around travel.
Melatonin is often treated as a low-risk, simple sleep aid, but in the US it is sold as an unregulated supplement rather than a controlled drug. Lab testing of commercial products found actual content ranging from under 100% to over 400% of the labeled dose — meaning two bottles claiming the same milligram amount can deliver wildly different actual doses. This undercuts the assumption that melatonin dosing is consistent or predictable across brands.