Melatonin

Melatonin is a hormone synthesized primarily by the pineal gland in the brain from the amino acid tryptophan, by way of serotonin. Its release follows a daily rhythm governed by the light-dark cycle: levels rise in the evening as darkness falls, peak overnight, and fall toward morning, which is why melatonin functions as the body's internal timing signal for sleep ^[1][2]. As a supplement, it is one of the most widely used and thoroughly studied sleep aids in the world.

Taken as a supplement, melatonin acts less like a sedative and more like a chronobiotic, a signal that nudges the body clock. Meta-analyses of randomized controlled trials show that it reduces the time needed to fall asleep, increases total sleep time, and improves overall sleep quality in people with primary sleep disorders ^[1][2]. It is particularly useful for circadian problems such as jet lag and shift-work schedules, where the aim is to shift the clock rather than simply to sedate; a systematic review found melatonin remarkably effective at preventing or reducing jet lag when taken near the target bedtime after crossing several time zones ^[3].

Melatonin is available over the counter in many countries as a dietary supplement, while in some jurisdictions it is regulated as a medicine, and it is sold in immediate-release and prolonged-release forms. It is generally regarded as safe and non-habit-forming for most adults, and its benefits do not appear to fade with continued use ^[1]. Beyond sleep, melatonin is also an antioxidant and has been studied for other roles, including neuroprotective effects in laboratory models ^[4]. The main practical consideration is timing, because taken at the wrong hour it can shift the body clock in an unhelpful direction ^[3].

Melatonin is generally well tolerated but can cause next-morning grogginess, headache, dizziness, and vivid dreams, and it should not be taken before activities requiring alertness such as driving. It may interact with anticoagulants, immunosuppressants, and sedatives, and because it is a hormone its long-term effects, particularly in children and during pregnancy, are not well characterized. Potency also varies widely between over-the-counter products.

The best-documented melatonin interaction is with fluvoxamine, a strong CYP1A2 inhibitor that markedly raises melatonin plasma concentrations (multi-fold increases in exposure) by blocking its primary metabolic pathway; other CYP1A2 inhibitors and, conversely, inducers such as smoking can shift melatonin levels similarly. Melatonin can add to the effects of CNS depressants and sedatives (benzodiazepines, alcohol, other hypnotics), increasing drowsiness. Several reports describe altered anticoagulant response, including raised INR and bleeding, when melatonin is taken with warfarin, so caution with anticoagulants is advised. It may also modestly affect blood pressure and glucose control, potentially interacting with antihypertensive and antidiabetic regimens. This is research information, not medical advice.

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Melatonin was discovered in 1958 by Aaron Lerner, a dermatologist at Yale University, who isolated the hormone from bovine pineal glands while searching for a substance that might affect skin pigmentation. He named it melatonin because it lightened the color of frog skin by aggregating the pigment within melanocytes, and its chemical identity as N-acetyl-5-methoxytryptamine was established soon after.

In the decades that followed, researchers uncovered its central role as the body's chemical signal of darkness, secreted by the pineal gland at night to help govern the sleep-wake cycle and other circadian rhythms. From the late twentieth century onward it became widely available as a dietary supplement, studied and used for insomnia, jet lag, and shifted sleep schedules. More recent research has revealed a deeper biology; melatonin is synthesized inside the mitochondria of nearly every cell and behaves as a potent antioxidant, a role thought to predate its later function as a sleep and timing signal.

Melatonin is one of the best-regarded sleep aids in the supplement world, prized for being effective in its niche, non-habit-forming, and remarkably gentle compared with conventional hypnotics. Its greatest strengths are as a circadian tool; systematic reviews and meta-analyses of randomized trials confirm that it modestly shortens the time to fall asleep, lengthens total sleep, and improves overall sleep quality, and that these benefits do not fade with continued use.

It is especially valued for jet lag and for realigning disrupted schedules, where correct timing of the dose matters as much as the amount. Honesty requires keeping expectations realistic; the effects on sleep are real but modest in size, and because melatonin shifts the clock, mistimed use can nudge the rhythm the wrong way. Dose-response research even suggests that taking it a few hours before the desired bedtime may work better than the usual bedtime dose. Beyond sleep, its antioxidant biology continues to intrigue researchers.