Melatonin is the world's best-selling sleep supplement and is available without a prescription in many countries. Despite its popularity, many people don't know exactly what melatonin does — and what it doesn't. A 2024 meta-analysis of 26 clinical trials and 1,689 participants found that melatonin has a real but modest effect on sleep onset.[1] This article presents what science confirms about melatonin's efficacy, dosage, and safety as a supplement.
How melatonin works in the body
Melatonin is a hormone produced naturally by the pineal gland as ambient light decreases, signaling to the body that it's time to prepare for sleep. It doesn't induce sleep like a sedative: its function is to regulate your biological clock, reducing alertness and lowering core body temperature. Endogenous production begins rising about 2 hours before your usual bedtime, peaks around 3 am, and drops before dawn. Exposure to artificial light — especially the blue light from screens — can suppress melatonin production by up to 50%.[4] When taken as a supplement, exogenous melatonin mimics that natural signal. Levvi's Sleep domain in the Health Hub tracks your sleep patterns over time, helping you see whether supplementation is making a real difference.
What studies show about melatonin's efficacy
Melatonin reduces sleep onset latency — the time it takes you to fall asleep. The dose-response meta-analysis by Cruz-Sanabria et al. (2024) analyzed 26 clinical trials and found an average reduction of 7 minutes in sleep latency, with a dose-dependent effect.[1] An umbrella review from 2022, compiling multiple meta-analyses, confirmed robust evidence for improved latency in people with insomnia, but found no clear evidence of improvement in sleep efficiency.[2] In short: melatonin helps you fall asleep faster, but does not necessarily help you sleep better or longer. Levvi lets you log melatonin as a medication with an alarm set for the optimal time to take it.
Dose and timing: what science recommends
The ideal melatonin dose is lower than most people expect. The 2024 dose-response meta-analysis showed that 1 to 5 mg is effective, with little additional benefit above 5 mg.[1] Very high doses (10 mg or more) can cause residual daytime sleepiness and desynchronize your biological clock. Timing matters as much as dose: taking melatonin 1 to 2 hours before your desired bedtime maximizes the effect. For immediate-release formulas, the plasma peak occurs within 30 to 60 minutes. Extended-release formulas are better for people who wake during the night. Levvi's medication alarm can be set to ring at the optimal time, respecting your registered sleep schedule and helping you stay consistent.
Safety and side effects
Melatonin has a favorable safety profile in adults, with no evidence of dependence or suppression of endogenous production with long-term use. The 2022 umbrella review found no serious adverse effects in the trials analyzed.[2] The most common side effects — daytime drowsiness, mild headache, and dizziness — are usually linked to high doses. Interactions with hormonal contraceptives may increase melatonin levels, requiring dose adjustment. Anticoagulants, antihypertensives, and immunosuppressants may also interact. Pregnant or breastfeeding women should avoid melatonin due to insufficient safety data. Children should only use it under medical guidance. Levvi's dose log helps you keep track of your usage over time.
When melatonin is not enough
Melatonin helps reset your biological clock, but it doesn't replace good sleep hygiene. If sleep difficulties persist despite supplementation, it's worth investigating underlying causes: anxiety, sleep apnea, chronic pain, or excessive caffeine intake. An estimated 30 to 40% of adults experience insomnia symptoms at some point in their lives. Cognitive behavioral therapy for insomnia (CBT-I) is considered the first-line treatment, with long-term efficacy superior to medication.[4] Levvi lets you create recurring sleep hygiene tasks in the Self-Care menu — reducing screen time 1 hour before bed, keeping regular schedules, building relaxation rituals. These behavioral changes amplify melatonin's effect and often make it unnecessary.
Conclusion
Melatonin has proven efficacy for reducing sleep onset time, but it's not a magic solution for all sleep problems. Low doses of 1 to 5 mg, taken 1 to 2 hours before bedtime, offer the best balance of efficacy and safety. Combining it with consistent sleep hygiene habits is the smartest approach to improving the quality of your rest long-term.