Melatonin

melatonin

The sleep and circadian hormone, also promoted as an antioxidant for aging.

TypeSupplement / dietary

The grade answers: What does the human evidence support for: Sleep & circadian support?

Grade

Limited

The grade rates evidence quality — it is not advice to take or buy.

Class: Hormone / chronobiotic
Primary use: Sleep & circadian support
Evidence strength: medium
Last reviewed: 2026-07-01

Bottom line

Genuinely useful for circadian problems (jet lag, delayed sleep phase) at low doses; the broader 'antioxidant anti-aging' pitch is far more speculative — and most people take far too much.

What the evidence says

Melatonin has decent evidence for shifting circadian timing — jet lag, shift work, delayed sleep-phase — and modestly shortening time to fall asleep. That's a real, useful effect. The separate anti-aging narrative (melatonin as a systemic antioxidant, declining with age) is mechanistically interesting but not backed by human longevity outcomes. A practical issue: common doses (3–10 mg) are often 10–30× more than needed and can cause grogginess. Grade C: solid chronobiotic, unproven geroprotector.

Key studies

[1]
Melatonin for jet lag and circadian disorders · review
Effective for circadian realignment at low doses.
Open on PubMed ↗
[2]
Melatonin and sleep onset (meta-analysis) · meta-analysis
Modest reduction in time to fall asleep.
Open on PubMed ↗
[3]
Melatonin, antioxidant claims and aging (review) · review
Mechanistic; no human longevity outcomes.
Open on PubMed ↗

See all studies on PubMed ↗

Scoped PubMed search, not a curated bibliography: the individual PMIDs for this entry have not yet been verified one by one. For that reason it is not used to support a high grade and is awaiting review.

Mechanism

Secreted by the pineal gland on a light-dark rhythm, it signals 'biological night' via MT1/MT2 receptors to regulate sleep timing; it also has direct antioxidant activity in vitro.

Safety

Short-term use is well tolerated; side effects include grogginess, vivid dreams and next-day sedation, usually dose-related. Long-term and developmental safety data are limited; regulatory status varies by country (prescription in some, OTC in others).

Dosage context

For circadian effects, low doses (~0.5–1 mg) taken at the right time often work better than the large 3–10 mg doses sold; timing matters more than amount.

Examples of application

Used at a low dose (~0.5–1 mg) at the right time for jet lag or sleep timing.
Timing matters more than amount; most bottles are overdosed.
A circadian signal, not a sedative or proven anti-aging antioxidant.

From the field

Melatonin is a timing signal, not a sleeping pill — and definitely not a proven anti-aging antioxidant. Lower doses, right timing. We grade it C and gently note most bottles are wildly overdosed.

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How we assign grades → Method