Melatonin is a hormone sold as an OTC dietary supplement in the United States and as a prescription medicine in some other countries. This page describes studied and hypothesized effects, not established treatments, and is not medical advice.
Overview
Melatonin is the body's night-time signal, produced by the pineal gland in darkness. Because it helps align internal rhythms with the light-dark cycle, most interest in melatonin centres on:
- Supporting sleep onset in people whose timing is disrupted.
- Shifting the phase of the circadian clock (a "chronobiotic" effect).
- Laboratory-studied antioxidant activity.
These are the areas researchers study; they are not a promise of any specific outcome for a given individual.
Sleep and circadian timing
Melatonin is often described more as a timing signal than as a classic sedative. Rather than forcing sleep, it can nudge the circadian clock, which is why the timing of exposure relative to a person's own rhythm is a central theme in the research.
- Effects are frequently described as modest and depend on individual circadian phase.
- Its influence on sleep onset differs from its influence on circadian alignment.
- Response varies with age, light exposure, and baseline sleep patterns.
Jet lag and shift work
One of the more studied applications is circadian misalignment from travel across time zones or shift work. Because melatonin can help shift the body clock, it has drawn research interest for helping realign internal timing after rapid changes in the light-dark schedule. As with sleep, the reported effects are generally modest and context-dependent.
Antioxidant research interest
Beyond its circadian role, melatonin has been studied in laboratory settings as a direct and indirect antioxidant. This has generated interest in a range of exploratory areas, though laboratory antioxidant activity does not automatically translate into clinical benefit in people. This remains an area of ongoing investigation rather than established use.
Evidence and caveats
Melatonin has a comparatively large evidence base for a sleep-related compound, but well-characterised short-term effects are not the same as proven long-term benefit. Key caveats:
- It is a hormone, not an inert sleep additive.
- As a US supplement, product content and labeling accuracy can vary.
- Timing relative to circadian phase strongly influences the effect.
- It is entirely distinct from Melanotan, an unrelated class of peptides.