Melatonin is the hormone that most adults take wrong. The over-the-counter supplements are dosed at 5 to 10 mg, which is 10 to 100 times the physiological dose your body actually produces. Used at those doses regularly, it does not produce the benefits the marketing suggests and may produce downsides.
That said, melatonin is a legitimate clinical tool when used correctly. It is also more than a sleep hormone, which is part of why the picture has gotten confused.
What melatonin actually does
The pineal gland produces melatonin in response to darkness. Levels rise in the evening, peak in the middle of the night, and fall toward morning. The function is to signal it is night to every system in the body that runs on a circadian rhythm.
The downstream effects:
- Sleep onset and maintenance. Helps initiate sleep and supports the architecture of the night.
- Circadian timing. Reinforces the circadian rhythm of every tissue.
- Antioxidant defense. Melatonin itself is one of the stronger antioxidants the body produces. Levels in some tissues are higher than blood levels, suggesting local production for protection.
- Immune modulation. Affects immune function in ways still being characterized.
- Mitochondrial protection. Concentrates in mitochondria specifically and reduces oxidative damage.
Most of these effects depend on the natural, physiological pulse of melatonin during the night. Replicating that pulse with exogenous melatonin is harder than the supplement aisle implies.
The dosing problem
The body produces roughly 0.3 mg of melatonin per night. Most over-the-counter supplements contain 5 to 10 mg, sometimes more. Higher doses do not produce better sleep. They produce different sleep:
- Vivid dreams or nightmares, sometimes severe
- Morning grogginess that can last hours
- Reduced REM sleep compared to lower doses
- Tolerance and dependence patterns in chronic users
The clinical evidence supports doses in the 0.3 to 0.5 mg range for most adults, occasionally up to 1 to 3 mg for specific contexts like shift work or jet lag. The higher doses people commonly take are essentially overdosing.
When melatonin actually works clinically
A few uses have meaningful evidence.
Jet lag. Low-dose melatonin (0.5 mg, 30 to 60 minutes before target bedtime at the destination) helps shift the circadian rhythm. One of the better-supported uses.
Delayed sleep phase disorder. Patients whose natural sleep timing is shifted late benefit from low-dose evening melatonin combined with morning light therapy.
Shift work sleep disorder. Strategic melatonin dosing can help shift workers maintain a daytime sleep schedule.
Some forms of insomnia, particularly sleep-onset insomnia. Low-dose, time-restricted use.
Pediatric sleep, particularly in children with neurodevelopmental conditions. With pediatric supervision.
Adjunct to certain cancer treatments. Some research suggests benefit. Coordinate with oncology.
When melatonin is overused
The pattern I see most often: a patient takes 5 to 10 mg every night for months or years for general sleep complaints. The benefits at that dose and frequency are modest, and the underlying sleep issue usually has a different driver (poor sleep hygiene, untreated sleep apnea, anxiety, hormonal pattern, circadian misalignment).
Melatonin is not a substitute for fixing the actual sleep problem.
What to do if you currently take melatonin
If you have been taking high-dose melatonin nightly:
- Reduce the dose first. Try 1 mg or 0.5 mg. Most patients sleep at least as well.
- Consider taking it only when needed. Not every night.
- Address the underlying driver. Sleep environment, sleep timing, light exposure, alcohol, evening eating, stress. The high-leverage moves are not pharmacologic.
- Consider stopping for a few weeks and seeing what your natural sleep looks like. Often better than expected once the supraphysiological dose stops disrupting natural production.
What about melatonin for non-sleep uses
The antioxidant, immune, and mitochondrial effects of melatonin are real and increasingly researched. The clinical applications are still being developed.
I do not currently prescribe high-dose melatonin for these uses outside specific clinical contexts. The data is interesting; it is not yet at the point where I would recommend it for the general adult.
If you want a physician to assess whether your melatonin use is appropriate, the path in is the Precision Call.
