Pharmacology · Other hypnotics (melatonin agonists and orexin antagonists)
Melatonin !
The body's darkness hormone, taken as a medicine or supplement for jet lag and some sleep-timing problems. Evidence for chronic insomnia is weak.
Updated 2026-11-01
The figure shows 2-iodomelatonin, a close melatonin analogue that occupies the same site, bound to the human MT1 receptor with its G protein; no clean structure with melatonin itself on MT1 is listed.
Mechanism of action
Melatonin is made by the pineal gland in darkness and tells the body's 24-hour clock that it is night. Taken as a medicine, it stimulates MT1 and MT2 receptors in the brain's clock, which can shift the timing of sleep.
- Darkness: the pineal gland releases melatonin
- Melatonin stimulates MT1 and MT2 receptors in the brain's clock
- The body clock shifts toward night and sleep
Pharmacokinetics
- Absorption
- Given by mouth; most products are made synthetically
Indications
- Jet lag, especially after eastward travel (limited evidence)
- Delayed sleep-wake phase disorder
- Some sleep problems in children, after behavioural measures
- Insomnia: evidence is insufficient for chronic insomnia Insomnia disorder →
Adverse effects
Common
- Drowsiness
- Headache
- Daytime sleepiness in older adults
Contraindications
- Allergy to melatonin products
- Not advised in people with dementia (guidelines)
Key interactions
- Blood thinners (anticoagulants)
- Possible interaction; checked with the prescriber
- Antiseizure medicines
- Possible interaction in people with epilepsy
What is monitored
- Daytime drowsiness, especially in older adults
- Whether sleep timing actually improves
Administration and safety
- Given by mouth
- Supplement products vary in content; a regulated product is preferred
- Stored out of reach of children
Nursing care
- Ask about all supplements, including melatonin, during medication history
- Teach sleep hygiene and light exposure as first steps
- Teach safe storage of gummies away from children
Pregnancy and breastfeeding
Research in pregnancy and breastfeeding is limited, so safety is not established.
Test yourself
Think of the answer, then tap the question to see it.
Which gland makes melatonin, and what triggers its release?
The pineal gland, in response to darkness.
For which travel problem does melatonin have some evidence?
Jet lag, especially after flying east.
Why is safe storage of melatonin gummies important?
Accidental ingestion by young children is a serious concern.
Related drugs
Related conditions
← Back to the class: Other hypnotics (melatonin agonists and orexin antagonists)
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Melatonin: What You Need To Know (National Center for Complementary and Integrative Health (NIH), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026); 7VGY: Melatonin receptor1-2-Iodomelatonin-Gicomplex (RCSB Protein Data Bank, 2022).
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Representative model, for educational purposes only.