What do the trials say — and why is the modest finding the honest one?
Melatonin's evidence base is large, contested in its average interpretation, and clearest in its specifics: the jet-lag evidence is decisive (the Cochrane-backed protocol), the sleep-onset benefit is real but modest (~7–12 minutes faster sleep in meta-analyses — the finding the marketing inflates), the dose-paradox work (MIT's 0.3 mg program) is the field's most practically useful finding, and the special populations (blind individuals with free-running clocks, children with neurodevelopmental conditions, delayed phase disorder) carry the strongest individual-patient evidence. The honest summary: a real chronobiotic, modestly effective for sleep onset, decisively effective for jet lag, and consistently over-dosed by the market.
The field teaches chronobiotic-vs-hypnotic reading — the skill the market lacks:
McCord and Allen discover that pineal extract lightens amphibian skin — the first hint that the pea-sized gland produces a biologically active compound.
From 250,000 bovine pineals: a few milligrams of the melanin-adjusting hormone — named for its skin effect, destined for its clock role.
Melatonin's secretion is found to be driven by the light-dark cycle — the pineal converts light information into a chemical timing signal.
Wurtman's group establishes the physiologic dose (~0.3 mg), the dose paradox, and the supplement's proper role — the science the shelf largely ignored.
The jet-lag literature matures and the Cochrane review confirms: timed melatonin is effective — the molecule's most decisive evidence.
Blind free-running rhythms, pediatric neurodevelopmental sleep, and delayed-phase disorder — the populations where the chronobiotic is genuine medicine, and the average adult is the modest-effect audience.
POPULATION · Adults and older adults across the controlled-dose melatonin studies
FINDING · 0.3 mg melatonin — the dose that reproduces the physiologic nighttime rise — improved sleep onset as well as or better than 3–10 mg, with less morning grogginess. The dose paradox established.
LIMITATION · Small-to-moderate samples, the group's program (single-lab concentration); the dose-finding has been broadly replicated and the shelf has broadly ignored it.
POPULATION · Blind individuals with non-24-hour sleep-wake disorder
FINDING · Timed melatonin anchors the free-running clock to a 24-hour cycle — the chronobiotic as genuine medicine in the population that needs it most.
LIMITATION · Small population, individualized timing protocols — but the mechanism's clearest clinical demonstration, and the approved-indication basis in several countries.