Melatonin half-life
Immediate-release melatonin has a half-life of about 40 minutes, so blood levels rise and fall fast. Sustained-release versions are formulated to release it gradually over roughly 5 to 8 hours, which gives a longer, flatter curve. The exact window varies by product.
This one depends on the version. The figure above is the first one listed. Different esters and routes clear at genuinely different speeds, so check which one you actually have before using this number.
What a half-life actually means
A half-life is the time it takes for half of what is in your blood to be gone. It does not mean the compound is finished at that point. Half goes, then half of what is left goes, and so on.
That is why the last traces take so much longer to disappear than the first. Most references treat something as effectively cleared after about five half-lives, which for Melatonin is roughly 3.3 hours.
How Melatonin clears
| Half-lives | Time since dose | Roughly left |
|---|---|---|
| 1 | 40 minutes | 50% |
| 2 | 1.3 hours | 25% |
| 3 | 2 hours | 12.5% |
| 4 | 2.7 hours | 6.25% |
| 5 | 3.3 hours | 3.125% |
These are round numbers from a single half-life figure. Real clearance shifts with dose, body composition, liver and kidney function, and what else you are taking. Treat it as a shape, not a schedule.
Why the timing matters
A short half-life means levels swing between doses, so timing and frequency do most of the work. A long half-life means levels build for days or weeks before they settle, so a change you make today might not show up for a while, and stopping does not clear things straight away.
Melatonin sits at about 40 minutes, so it behaves like the short end of that range.
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On a repeating schedule the amount in your body climbs until what you take in each interval matches what clears in it. That plateau is called steady state, and it arrives after roughly five half-lives whatever the dose. For Melatonin that is about 3.3 hours of consistent dosing.
The typical starting schedule is 30-60 min pre-bed, at 0.5 mg. Until that plateau, every dose lands on top of more of the last one than it will later, which is why the first weeks of a protocol can feel different from the same dose a month in.
Skipping doses resets part of that climb. One missed dose costs roughly one half-life of accumulation, so the shorter the half-life the more a gap matters.
Mixing and measuring Melatonin
Oral tablet / capsule / gummy
Store at 15-25°C (room temp), keep dry. 2 years sealed.