Melatonin
Indoleamine hormone derived from tryptophan
- Class
- Sleep hormone
- Half-life
- ~30–60 min
- Route
- Oral
- Cadence
- Daily
- Evidence
- Human clinical trials
Overview
Melatonin is the pineal gland's main nighttime hormone — your body makes it when the lights go off, and it tells your brain it's time to sleep. Oral melatonin (typically 0.5–10 mg) is used for jet lag, shift work, insomnia, and circadian rhythm disorders. It works, but not the way most people think: it doesn't knock you out like a sedative; it nudges your internal clock forward or backward depending on when you take it.
The sleep effect is real but modest. Most trials show melatonin cuts the time it takes to fall asleep by 7–12 minutes and adds 15–30 minutes of total sleep time. That's clinically meaningful for people whose circadian rhythm is genuinely out of sync (delayed sleep phase, jet lag), but it's not a cure for garden-variety insomnia driven by stress or poor sleep hygiene.
Safety record is good — decades of use, minimal reported toxicity. But the unregulated supplement market is a mess: independent testing routinely finds actual melatonin content ranging from 83% below to 478% above the label claim, and some products contain serotonin (a controlled precursor) as a contaminant.
Safety considerations
A few of the safety signals worth knowing — the full list, with dosing context and what to monitor, is inside AIx Core.
- Generally recognized as safe at doses up to 10 mg/day. Decades of use, minimal reported acute toxicity.
- Pregnancy and lactation: safety data are thin. One review concluded use is 'probably safe,' but no controlled trials have been done. Avoid unless specifically advised by a clinician.
- Can interact with immunosuppressants, anticoagulants (warfarin), and antihypertensives — melatonin has mild effects on blood pressure and immune function.
+ 3 more safety notes inside AIx Core →
Commonly monitored
Markers and signals people track when researching Melatonin.
- Sleep latency (how long it takes to fall asleep)
- Total sleep time
- Sleep quality (subjective — do you feel rested?)
- Morning grogginess or daytime sedation
- Mood changes (rare reports of vivid dreams or dysphoria)
Frequently asked questions
What is Melatonin?
Indoleamine hormone derived from tryptophan. Melatonin is the pineal gland's main nighttime hormone — your body makes it when the lights go off, and it tells your brain it's time to sleep. Oral melatonin (typically 0.5–10 mg) is used for jet lag, shift work, insomnia, and circadian rhythm disorders. It works, but not the way most people think: it doesn't knock you out like a sedative; it nudges your internal clock forward or backward depending on when you take it.
How is Melatonin administered?
Oral, typically daily.
What is the half-life of Melatonin?
~30–60 min — Short plasma half-life; effects on sleep architecture persist longer.
Is Melatonin approved for human use?
Melatonin is investigational — not approved by the FDA, EMA, or MHRA for human use at the time of writing.
What does the evidence show for Melatonin?
Evidence tier: Human clinical trials. Meta-analysis (Ferracioli-Oda 2013, 19 trials, n=1,683): melatonin reduced sleep onset latency by 7.06 minutes (95% CI: 4.37–9.75) and increased total sleep time by 8.25 minutes — statistically significant but clinically modest.
What is commonly monitored when researching Melatonin?
Commonly tracked markers + signals: Sleep latency (how long it takes to fall asleep), Total sleep time, Sleep quality (subjective — do you feel rested?), Morning grogginess or daytime sedation, Mood changes (rare reports of vivid dreams or dysphoria).
Open this in AIx Core for the full picture
Mechanism breakdown, receptor pathway diagram, full safety list, monitored items, source citations, and one-tap add-to-protocol. Free with any account.