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Melatonin is one of the most popular sleep aids in America, sold as tablets, gummies and sprays in almost every drugstore. Because it’s a hormone your body already makes, many people assume it’s harmless and works for any kind of sleeplessness. The reality is more nuanced: melatonin helps in specific situations, label doses vary widely, and some people should skip it entirely.
- Melatonin is a timing signal for your body clock, not a sedative; evidence is strongest for jet lag, not chronic insomnia.
- Over-the-counter products commonly come in the 1 to 5 milligram range, and labels are often inaccurate.
- Common side effects include headache, dizziness, nausea and daytime drowsiness.
- People who are pregnant, breastfeeding, have bleeding or seizure disorders, or take certain medicines should talk to a clinician first.
How melatonin works in your body
Melatonin is a hormone your brain releases in response to darkness. According to the Sleep Foundation, the body starts producing it in the evening around sunset. Levels peak roughly seven hours after sunset and drop to undetectable levels as morning light arrives.
Think of melatonin as a “darkness signal.” It tells your internal clock that night has begun, which nudges the timing of sleep. It doesn’t knock you out the way prescription sleeping pills do. That’s why it tends to be more useful for shifting your schedule, as with jet lag, than for fixing insomnia caused by stress, pain or other problems.
Because light is what shuts melatonin production off, keeping evenings dim and getting light in the morning are free ways to work with this system.
What the research shows melatonin helps with
The National Center for Complementary and Integrative Health (NCCIH) summarizes the evidence this way:
- Jet lag: Moderate evidence of benefit. Studies found melatonin may reduce symptoms after eastward and westward flights.
- Shift work: Inconclusive. One review found people may sleep about 24 minutes longer during the day, but other sleep measures showed no clear improvement.
- Chronic insomnia: The American Academy of Sleep Medicine (2017) and American College of Physicians (2016) concluded there isn’t enough strong evidence on its effectiveness or safety.
For long-term insomnia, the American College of Physicians recommends cognitive behavioral therapy for insomnia (CBT-I) as the first-line treatment, not supplements.
Typical doses on product labels
This section describes what’s sold and what general sources report. It is not a dosing recommendation for you; a pharmacist or doctor can help with that.
| What you’ll see | What sources report |
|---|---|
| Common over-the-counter strengths | Roughly 1 to 5 mg for adults and teens (Sleep Foundation) |
| Lower doses | Research suggests doses under 1 mg may be as effective for some people (Sleep Foundation) |
| Upper limit cited by Sleep Foundation | 10 mg in a 24-hour period |
| Timing on many labels | About 20 to 40 minutes before bed; effects last about 4 to 8 hours (Sleep Foundation) |
| Label accuracy | 22 of 25 gummies tested in a 2023 study were mislabeled, some with up to 3.5 times the stated amount (NCCIH) |
Because melatonin is sold as a dietary supplement in the U.S., it doesn’t go through the FDA approval process that drugs do. NCCIH also notes a 2017 study in which melatonin content often didn’t match labels and 26% of supplements contained serotonin. Choosing a product with independent third-party testing can reduce, but not eliminate, that uncertainty.
Bigger isn’t better. Sleep Foundation notes that experts generally suggest starting low and that lower doses may work as well as higher ones.
Side effects of melatonin
Short-term use appears safe for most adults, but long-term safety data are limited, NCCIH says. Mayo Clinic lists these side effects:
- Common: headache, dizziness, nausea and daytime drowsiness.
- Less common: vivid dreams or nightmares, short-term feelings of depression, irritability, stomach cramps, loose stools or constipation, reduced appetite and nighttime urinary incontinence.
- Other concerns: confusion, reduced alertness and an increased risk of falls.
Mayo Clinic advises not driving or operating machinery within five hours of taking melatonin.
New questions about long-term use
In late 2025, preliminary research presented at the American Heart Association’s Scientific Sessions linked more than a year of melatonin use in adults with chronic insomnia to higher rates of heart failure over five years, according to Nutritional Outlook. The study was observational and not yet peer-reviewed, and its lead author said it can’t prove cause and effect. It’s a reason for caution about daily, open-ended use rather than a reason to panic.
Who should avoid melatonin or check first
Sleep Foundation and Mayo Clinic flag several groups who should not take melatonin without medical advice:
- People who are pregnant or breastfeeding.
- People with bleeding disorders or who take blood thinners.
- People with seizure disorders or on anti-seizure medicines.
- People with depression, or taking certain antidepressants such as SSRIs.
- Organ transplant recipients and anyone on immunosuppressants.
- People taking birth control pills, blood pressure medicine or diabetes medicine.
Children and melatonin
Melatonin gummies look like candy, and that has consequences. NCCIH reports that the CDC estimated about 11,000 emergency department visits from 2019 to 2022 for unsupervised melatonin ingestion by children age 5 and younger. Poison control calls for people 19 and younger rose from 8,337 in 2012 to 52,563 in 2021. Store melatonin out of reach, and ask a pediatrician before giving it to a child.
Smarter ways to use (or skip) melatonin
If you and your clinician decide melatonin makes sense, a few habits help:
- Use it for a specific purpose, like adjusting to a new time zone, rather than nightly by default.
- Pair it with habits that reinforce your body clock: morning light, a consistent wake time and dim evenings.
- Bring the bottle to appointments so your doctor or pharmacist can check for interactions.
Many people also lean on non-supplement wind-down rituals. A warm, caffeine-free cup, such as some Ayurvedic herbal teas, can be part of a calming routine. And if you’re already taking several supplements, review whether you need them; our guide to vitamins and minerals people commonly take daily is a useful starting point for that conversation.
See a healthcare professional if insomnia lasts more than a few weeks, if you rely on melatonin most nights, or if you snore loudly, gasp at night or feel very sleepy during the day. Contact Poison Control or seek care if a child swallows melatonin. Check with a doctor or pharmacist before using melatonin if you are pregnant, breastfeeding, have a chronic condition or take prescription medicines.
Frequently asked questions
Is melatonin habit-forming?
Sleep Foundation says melatonin is not believed to be habit-forming. Long-term safety, however, hasn’t been well studied.
Does melatonin work for insomnia?
Major sleep and physician groups found there isn’t enough strong evidence to recommend it for chronic insomnia. It has better support for jet lag.
Why do melatonin products contain different amounts than the label says?
Supplements aren’t approved by the FDA like drugs. Testing has found many products contain much less or more melatonin than listed.
Can I drive after taking melatonin?
Mayo Clinic advises avoiding driving or operating machinery within five hours of taking it because it can cause drowsiness.
Is melatonin safe for kids?
Ask a pediatrician first. Accidental ingestions in young children have climbed sharply, so store it like medicine.
Sources
- NCCIH, Melatonin: What you need to know
- Mayo Clinic, Melatonin side effects
- Sleep Foundation, Melatonin and sleep
- Nutritional Outlook, AHA study finds potential connection between long-term melatonin use and heart health outcomes
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