Melatonin Dosage Calculator

Melatonin is a naturally occurring hormone produced by the pineal gland in response to darkness. It plays a central role in regulating the body's circadian rhythm — the roughly 24-hour internal clock that governs sleep and wakefulness, hormone release, body temperature, and many other physiological processes. As a supplement, melatonin is widely used to help people fall asleep faster, adjust to new time zones, adapt to rotating shift schedules, or simply promote a sense of calm relaxation before bed. Unlike many sleep aids, melatonin is not a sedative. It works by signalling to the brain that darkness has arrived and that it is time to prepare for sleep, which is why timing is often as important as dose. Taking melatonin 30–60 minutes before a desired bedtime is generally recommended for most sleep-onset purposes. For jet lag, strategically timed doses at the destination's local bedtime can accelerate circadian re-entrainment by one to two days. Dosing recommendations have evolved considerably over the past decade. Early clinical studies often used doses of 5–10 mg, but more recent research suggests that much smaller doses — in the range of 0.1–0.5 mg — can be equally effective for many individuals while causing fewer next-day side effects such as grogginess or daytime sleepiness. This calculator uses a weight-based approach to estimate a starting dose, because body weight is one of the factors that influences how quickly melatonin is metabolised. Adults metabolise melatonin differently than children, which is reflected in the separate dosing factors applied. The purpose multiplier accounts for the fact that different applications call for different pharmacological profiles. Jet lag recovery, for example, benefits from a slightly lower dose that avoids excessive daytime sedation during travel. Shift work adjustment, by contrast, may warrant a marginally higher dose to overcome stronger circadian resistance when sleeping at non-traditional hours. General relaxation without a primary sleep disorder is best served by the lowest effective dose. It is important to understand that this calculator provides a suggested starting dose only, not a prescription. Individual responses to melatonin vary substantially due to differences in enzyme activity (primarily CYP1A2), age-related changes in pineal gland output, medication interactions, and underlying health conditions. Always start at the lowest calculated dose, and only increase gradually if the initial dose is insufficient. Children and adolescents should use melatonin only under medical supervision. Pregnant or breastfeeding individuals should consult a healthcare provider before use. Melatonin may interact with anticoagulants, immunosuppressants, and certain antidepressants.