Melatonin

What it is

Melatonin is a hormone and supplement that helps regulate the sleep-wake cycle over a roughly 24-hour circadian rhythm. Your brain, mainly the pineal gland, releases more melatonin in darkness and less in light, which helps signal that it is time to sleep. The most important practical point is that melatonin is usually more helpful for circadian-timing problems such as jet lag and delayed sleep-wake phase disorder than for chronic insomnia alone.

Melatonin is often called the “sleep hormone,” but it does not work like a general sedative for everyone. In the body, it is part of the circadian system that coordinates sleep timing with the light-dark cycle. Melatonin production tends to decline with age, which may partly explain why some older adults respond better to supplements.

As a supplement, melatonin is usually sold as tablets, capsules, gummies, or prolonged-release products. In many countries it is regulated differently from prescription medicines. Product quality can vary, so the amount on the label may not always match the amount in the product. In India, melatonin products are available in the supplement and medicine market, but consumers should still check labeling carefully and use reputable brands.

How it works

Melatonin acts on MT1 and MT2 receptors in the brain, especially in pathways linked to the suprachiasmatic nucleus, the body's main circadian clock. In simple terms, it helps the body align sleep timing with darkness.

Two effects matter most:

1. Chronobiotic effect: It can shift the timing of the body clock earlier or later depending on when it is taken.
2. Sleep-promoting effect: It may make it easier to fall asleep, especially when the body is not producing enough melatonin at the right time.

Light exposure strongly affects melatonin. Bright light at night, including from phones and other screens, can suppress natural melatonin release. That is one reason sleep hygiene advice often includes dimming lights in the evening.

A simple comparison is below:

Form	Main idea	Typical use
Immediate-release	Rises quickly	Trouble falling asleep, jet lag, delayed sleep timing
Prolonged-release	Releases more slowly	Sometimes used when staying asleep is also a problem, especially in older adults

Evidence and uses

The best-supported uses of melatonin are circadian rhythm sleep disorders and jet lag. Evidence for general insomnia is more modest.

Uses with better support

• Jet lag: Reviews cited by NCCIH found benefit after crossing multiple time zones, including studies in 142 travelers after eastward flights and 90 travelers after westward flights.
• Delayed sleep-wake phase disorder: A small review found melatonin reduced sleep-onset time by about 22 minutes versus placebo. A 2018 randomized trial in 307 people found melatonin taken 1 hour before the desired bedtime, along with a fixed bedtime, helped people fall asleep about 34 minutes earlier.
• Circadian rhythm disorders in blind people: Melatonin can help some people whose body clock is not well synchronized to the 24-hour day.

Uses with mixed or limited support

• Insomnia: Melatonin may slightly shorten the time it takes to fall asleep, but effects on total sleep time and sleep quality are less consistent. It may be more useful in older adults or in people whose sleep problem is related to circadian timing.
• Sleep problems in children: Some small studies suggest benefit in selected children, including some with neurodevelopmental conditions, but behavioral sleep strategies are usually first-line. Parents should not start it without a clinician's advice.
• Perioperative anxiety or sleep-related uses outside standard indications: Some studies suggest possible benefit, but this is not a routine reason to self-treat.

Melatonin is not a cure for poor sleep caused by untreated sleep apnea, depression, chronic pain, stimulant use, heavy alcohol use, or irregular schedules. In those situations, treating the underlying cause matters more.

Safety and interactions

Melatonin is generally considered safe for short-term use in adults, but “natural” does not mean risk-free. Common side effects include headache, dizziness, nausea, and next-day drowsiness. Less common effects can include irritability, vivid dreams, mild anxiety, abdominal cramps, confusion, or short-lasting low mood.

Important safety points:

• Do not drive or operate machinery if you feel drowsy after taking it.
• Product strength and purity may vary between brands.
• People with autoimmune disease should ask a clinician before use; some sources advise avoiding it.
• Pregnancy, breastfeeding, and long-term use in children need medical guidance because safety data are more limited.

Potential interactions include:

Medicine or class	Why it matters
Anticoagulants or antiplatelet drugs	May increase bleeding risk
CNS depressants, alcohol, sedating medicines	Can add to drowsiness and impair alertness
Blood pressure medicines	May affect blood pressure control
Diabetes medicines	May affect glucose regulation
Anticonvulsants	May interfere with seizure control in some people

Talk to a clinician or pharmacist before using melatonin if you take regular medicines, have epilepsy, have a bleeding disorder, or have major liver or kidney disease.

When to see a clinician

See a clinician if sleep problems last more than a few weeks, keep returning, or affect work, school, mood, or safety. You should also seek care if you snore loudly, stop breathing during sleep, have restless legs, severe daytime sleepiness, or symptoms of depression or anxiety.

Melatonin should not be used to delay evaluation of chronic insomnia. Persistent sleep problems can be caused by sleep apnea, thyroid disease, medication effects, circadian disorders, mental health conditions, or other medical issues.

Children, older adults with falls risk, and people taking multiple medicines should get individualized advice before use. In India as elsewhere, a qualified physician can help distinguish simple sleep timing problems from disorders that need formal treatment.

Limitations and open questions

Evidence in humans is stronger for circadian rhythm problems than for broad claims about sleep, immunity, aging, or brain health. Many studies are small, use different doses and formulations, and measure different outcomes, which makes results hard to compare.

Long-term safety is not fully settled, especially for routine use over months to years, for children, and for people with complex medical conditions. Another limitation is supplement quality: independent testing has found that some products contain more or less melatonin than the label states.

There is also no single best dose or timing that fits everyone. Melatonin works partly by timing, not just by amount, so taking it at the wrong time may reduce benefit or even shift the body clock in the wrong direction. That is why persistent sleep problems are better managed with a clinician, especially if melatonin has not helped after a short trial.