Melatonin is a hormone produced mainly by the pineal gland in the brain. The body releases more melatonin in darkness. The hormone helps regulate the circadian rhythm, the internal 24-hour clock that controls sleep and wake timing. A July 2024 explanation from the National Institute of General Medical Sciences describes the distinction between hormones and neurotransmitters.
Melatonin at a Glance
| Question | Answer |
|---|---|
| Is melatonin a hormone? | Yes. |
| Where is melatonin produced? | Mainly in the pineal gland in the brain. |
| What triggers melatonin release? | Darkness. |
| What does melatonin regulate? | Circadian rhythm and sleep timing. |
| Is supplement melatonin the same hormone? | Yes. Supplements contain the same melatonin molecule, usually made synthetically. |
What Does Melatonin Do?
Melatonin signals that the body's biological night is approaching. Melatonin levels usually rise after darkness and help coordinate the timing of sleep. Light exposure at night can reduce or suppress melatonin production.
Melatonin is mainly a sleep-timing hormone. It helps the body prepare for sleep, but it does not always cause someone to fall asleep immediately.
Is Melatonin in Supplements the Same as the Body's Melatonin?
Yes. Melatonin supplements contain the same hormone made naturally by the body. Most melatonin supplements sold in the United States are made synthetically, although some products may come from animals or microorganisms.
The difference is the amount and timing. The body releases its own melatonin in response to the light-dark cycle. A supplement adds melatonin at a chosen time.
Is Melatonin a Hormone or a Neurotransmitter?
Melatonin is classified as a hormone. Hormones are chemical messengers released by glands and carried through the bloodstream to affect tissues and organs. Neurotransmitters mainly carry signals between nerve cells or between nerve cells and muscles.
Melatonin interacts with the nervous system because it affects the brain's circadian clock. Its primary classification is still a hormone.
Does Taking Melatonin Affect Other Hormones?
It can. Melatonin supplements provide more of the hormone than the body may produce at that moment, and the long-term effects of supplementation are less certain. Melatonin can interact with medicines, so people who are pregnant, breastfeeding, taking blood thinners or using other medications should seek medical advice before taking it.
Children should not be given melatonin routinely without guidance from a healthcare professional. Researchers still have questions about appropriate dosing, long-term effects and possible effects on hormonal development.
Bottom Line
Melatonin is a hormone that helps set the timing of the sleep-wake cycle. Supplements contain the same molecule, but they deliver it in a different amount and at a chosen time. That makes medical guidance especially important for children, pregnant or breastfeeding people and anyone taking medication.