Melatonin

Updated June 3, 2026

Melatonin signals biological night to the suprachiasmatic nucleus, and at the right dose at the right hour it pulls the body's clock toward the sleep window you want. That mechanism is well established. It is a chronobiotic, not a sedative, which is why timing and dose carry more weight than the milligram count on the bottle suggests. A small, well-timed dose performs as well or better than the 3 to 10 mg drugstore tablet, and the physiologic dose people respond to is closer to 0.3 mg.

The reason the low dose works is straightforward. The pineal gland releases tiny amounts of melatonin in the evening, and the receptors are tuned for that scale. Flooding them with ten or twenty times the physiologic dose does not deepen the signal. It blurs it, extends the half-life into the next afternoon, and adds grogginess. Lower doses match the body's own release pattern and clear in time for a clean morning.

The pineal signal is only one face of the molecule. Melatonin is also synthesized inside mitochondria of nearly every cell, and at concentrations far above what circulates in blood. There it functions as a direct scavenger of reactive oxygen and nitrogen species, including the peroxynitrite radical that ordinary antioxidants struggle to neutralize. It does this without being recycled, which means it acts as a terminal sink for free radicals rather than a regenerating shuttle. Both the parent molecule and its metabolites (AFMK and AMK) keep scavenging, a cascade that protects the inner mitochondrial membrane and helps preserve electron transport chain efficiency under oxidative stress. It also supports the activity of glutathione peroxidase and superoxide dismutase, the cell's own enzymatic antioxidant arms, which is why some of the strongest melatonin literature sits outside sleep entirely.

That mitochondrial role connects to a quieter anti-inflammatory effect. Melatonin dampens NF-kB signaling, lowers nighttime IL-6 and TNF-alpha activity in some clinical samples, and calms microglial activation in brain tissue. The downstream consequence is less neuroinflammatory tone overnight, which is part of why people often report cleaner mornings on a low dose even when sleep latency itself barely moves. It is also one reason researchers have looked at melatonin in contexts as different as migraine prevention, sepsis support, and post-stroke neuroprotection. Most of that work is still early. The mechanism, however, is real and is part of why the molecule is unusually well tolerated.

The evidence is strongest in three specific contexts, and in those contexts it is consistent. Jet lag responds to 0.3 to 0.5 mg at the destination's local bedtime for several days, with the eastward direction (which compresses your day) showing the cleanest effect. Delayed sleep phase syndrome and shift-work circadian disruption respond to low doses in the early evening, pulling circadian timing earlier over weeks. Older adults, whose endogenous melatonin production has declined with age, often get real sleep-onset help from small doses where a young insomniac would not. The age-related drop matters in two ways. Less circulating signal at night, and less mitochondrial antioxidant reserve to draw on. A small physiologic dose addresses both.

For the common "I have trouble falling asleep" case in healthy younger adults, the effect is real but smaller than the marketing suggests. A 2013 meta-analysis (Ferracioli-Oda and colleagues) found melatonin reduces sleep onset latency by about seven minutes on average and increases total sleep time by about eight minutes. Useful at the margin. CBT-I produces a larger effect for chronic insomnia, and the two are not in competition.

Dose for the common case. Start with 0.3 to 0.5 mg, taken thirty to sixty minutes before the bedtime you want to land at. A pill cutter handles standard tablets. Sublingual or liquid forms hit faster and let you titrate cleanly. If 0.5 mg does nothing after a week or two, 1 mg is reasonable. Going above 3 mg is rarely productive, and the 10 mg supermarket pill is pharmacological overshoot.

Timing is the lever most people miss. Taking melatonin at midnight after two hours of struggle does almost nothing for sleep onset, because the signal needs to reach the brain ahead of the desired sleep window. Take it on a schedule, the same time each evening, and the chronobiotic effect compounds. Skip the schedule and the supplement looks broken when the real failure is the clock.

Safety notes. Melatonin interacts with several medications, including some antidepressants (fluvoxamine increases melatonin levels several-fold), benzodiazepines, and blood pressure drugs. People with autoimmune conditions occasionally report flares, though the evidence is weak. Children should not take it casually. Pregnancy data is limited and the responsible move is to skip it. Quality control in US melatonin supplements has been historically poor: one 2017 audit (Erland and Saxena) found actual content ranged from 17 to 478 percent of the label across products tested, so a reputable brand matters more than usual here. None of this is medical advice. If you take prescription medication, are pregnant, have an autoimmune condition, or are considering melatonin for a child, ask a clinician first.

Glycine is a fair comparison point. Both are taken before bed, both are cheap, both have honest mechanisms. Glycine lowers core body temperature through peripheral vasodilation and improves subjective sleep quality. Melatonin moves the clock and quiets the oxidative tone of the night. The two solve different problems, and people with circadian timing issues should reach for melatonin first.

What you actually get from a well-run protocol. A reliable chronobiotic signal that lines up the body's internal night with the sleep window you want. Faster recovery from jet lag, especially eastward. A practical lever for shift workers and delayed sleep phase. Modest but real help with sleep onset and duration in the right user. A quieter mitochondrial and inflammatory backdrop while you sleep, which matters more as you age. Buy a low-dose product (0.3 to 1 mg) or cut a higher-dose pill, take it thirty to sixty minutes before target bedtime, and keep the timing consistent. The 10 mg tablet is a marketing artifact, not a better dose.