Why experts are cautious about using melatonin as a nightly habit
Matt Walker and Andrew Huberman both raise concerns about relying on melatonin, pointing out issues with dosing and questioning whether it is the right tool for most sleep problems. Readers reaching for a supplement habit should first understand these cautions and the behavioral alternatives.
Experts are cautious about nightly melatonin because it is a timing signal, not a sleeping pill. It tells the body that night has arrived, but it does not make sleep happen. For healthy adults the measured benefit is tiny, store doses are far above what worked in studies, and the label often does not match what is in the bottle.
Matt Walker, a sleep scientist at UC Berkeley, compares melatonin to the starting official at an Olympic 100-meter race: it calls the runners to the line but does not run the race. He cites a meta-analysis in which melatonin added only 3.9 minutes of total sleep for healthy, non-elderly adults, which he calls "a weak sauce effect". The doses that helped in studies were 0.1 to 0.3 milligrams, while store products commonly hold 5, 10 or more. In one study of more than 20 brands, the real content ranged from 83% less to 478% more than the label claimed.
Andrew Huberman's caution is more about hormones and staying asleep. He says melatonin helps people fall asleep but not stay asleep, and that many wake three to five hours later. He finds it odd that a hormone is sold over the counter. Melatonin acts on the hormones that drive testosterone and estrogen, and although the dramatic effects seen in seasonally breeding hamsters do not happen in humans, the mechanism makes him wary. His biggest worry is children, because melatonin is involved in the timing of puberty and the doses they may be getting have not been studied.
Both see the same narrow place for it: older adults, in discussion with a doctor. Walker's reason is that the pineal gland can calcify with age and flatten the nightly rise. Huberman doubts calcification is the problem it is made out to be, and reasons instead that the reproductive concern matters less late in life. Their label figures also differ, but all point the same way: you cannot trust the label to tell you the dose. Neither is absolutist. Huberman acknowledges that many people find melatonin helpful and says adults can decide with their physician.
Why it cannot carry the load: sleep is driven by sleep pressure, which builds from adenosine while you are awake, and by the body clock. Melatonin belongs only to the clock. Light works on the same system from the input side. Walker cites a study in which moving workers to window-facing desks raised total sleep by more than 30 minutes, against 3.9 minutes for melatonin.
What to do with it: ask how your sleep habits are before asking what to take. Huberman's order is "behavioral protocols first". Get outdoor light early in the day. Dim the lights in the evening and avoid bright light between 11 PM and 4 AM. Stop caffeine about 8 to 10 hours before bed, and do not treat alcohol as a sleep aid. Build a wind-down routine. For chronic insomnia, look into cognitive behavioral therapy for insomnia, which Walker says matches sleeping pills in the short term and beats them over time.
If you and your doctor decide to try melatonin, respect the small study doses and remember it will not keep you asleep. Anyone with a persistent sleep problem, or considering melatonin for a child, should talk with a doctor first.