Melatonin: a timing signal that gets used as a sedative, at doses far above what it needs

The most commonly misused compound in this reference, and the misuse is a dosing error rather than a safety one. It is a circadian signal, and most people take ten to a hundred times more of it than the signal requires.

A clock signal, not a sleeping tablet

Established clinical use Melatonin is secreted by the pineal gland as darkness falls and acts on receptors in the suprachiasmatic nucleus — the body clock. Its physiological job is to tell the system what time it is, not to induce unconsciousness. That distinction predicts almost everything about how it behaves: it shifts the timing of sleep reliably, and it produces sedation weakly.

Established clinical use The dose that saturates those receptors is small. Physiological nocturnal concentrations are reproduced by roughly 0.3 mg, and studies comparing doses for sleep onset have generally not found more to be better — higher amounts produce concentrations far above anything the body makes, sustained into the morning, which is where next-day grogginess comes from. The app’s own sleep row says 0.3 to 1 mg and explicitly advises against going higher for sleep, which is correct and unusual advice to find on a supplement.

Timing matters more than amount for the circadian use. Taken several hours before the desired sleep time it advances the clock; taken in the early morning it delays it. For jet lag and for delayed sleep phase, that is the mechanism doing the work, and getting the timing wrong can move the clock in the wrong direction.

The high-dose protocols, and where they come from

Animal-only or theoretical The app records therapeutic rows an order of magnitude higher, and those come from a different literature: melatonin as an antioxidant and mitochondrial protectant, and from oncology, where high-dose melatonin has been studied as an adjunct alongside conventional treatment. Some of that work reports benefit and much of it is small and open-label.

Two things follow. Those amounts are not for sleep — they are worse for sleep than the small ones — and the population they were studied in is people with cancer receiving treatment, which is not the population reading this page. Extrapolating an oncology adjunct dose into a longevity supplement is exactly the move this site keeps flagging.

Melatonin is a hormone, which the app’s own regulatory string says. Long-term high-dose use has not been characterised for its effects on the reproductive axis in adults, and the app puts reproductive hormones on the monitoring list for that reason — theoretical rather than demonstrated, and a reasonable thing to have measured rather than assumed.

Practical points

It is a supplement in the United States and a prescription medicine in much of Europe and in Australia, which tells you something about how the same evidence is read in different places. Independent analyses of commercial melatonin products have repeatedly found content varying widely from label, sometimes by several fold, and some products have been found to contain serotonin. This site names no brand and no testing service.

The interaction worth naming is with anticoagulants, where melatonin may add to bleeding risk, and with anything sedating. Anyone on either should be raising it rather than assuming an over-the-counter product is inert.

And the same caveat the DSIP page carries applies here: persistent sleep disruption is a symptom rather than a diagnosis, and sleep apnoea, thyroid disease, depression and medication effects are all worth excluding before treating it. Cognitive behavioural therapy for insomnia outperforms hypnotics in trials and keeps working after it stops.

The dosing rows the app records

Off-label or community practice Reproduced from the app’s reference so you can see what it holds, not as a recommendation. Which row applies to a particular person, if any, is a clinical decision this page does not make — and rows describing supraphysiological or post-cycle use are filtered out before this table is built, so what you see here is a subset.

What the app monitors alongside it

The panel below is the app’s own monitoring note for Melatonin (Therapeutic), verbatim. None of the analytes it names has a page here yet.

Drawbacks and risks the app records

From the app’s own entry, and the first two items are the practical consequences of taking a clock signal at sedative-sized amounts.

• High doses may cause morning grogginess
• Can suppress endogenous melatonin production at high doses
• Theoretical concern about reproductive hormones at very high doses
• Most high-dose human data from cancer contexts
• Not recommended during pregnancy
• Interacts with anticoagulants — check with physician

Questions people actually ask

How much should be taken for sleep?

Less than most products sell. Roughly 0.3 to 1 mg reproduces physiological concentrations, and comparisons have generally not found more to work better — higher amounts mainly add next-day grogginess. The app’s own row says the same.

Why does timing matter?

Because it acts on the body clock. Taken hours before the target sleep time it advances the clock; taken in the early morning it delays it. For jet lag that is the whole mechanism.

What are the 10 to 60 mg protocols for?

Not sleep. They come from antioxidant and oncology-adjunct work in people receiving cancer treatment, which is a different population and a different purpose. Using that dose for sleep makes sleep worse.

Is content on the label reliable?

Often not. Independent analyses have repeatedly found melatonin content varying widely from label, sometimes several fold, and it is a prescription medicine in much of Europe and Australia.

Where the load-bearing numbers come from

Named rather than linked. Publisher URLs move, and a citation that resolves to a 404 two years from now is worse than one you can search for by name — every entry below is findable from the title and year alone.