You're Probably Taking Way Too Much Melatonin
Most melatonin doses sold in the US are 5–10x higher than what research shows is effective. Here's what the science actually says.
Walk into any pharmacy or grocery store and you’ll find melatonin in doses of 5mg, 10mg, even 20mg. These numbers are so common they’ve come to feel normal. They aren’t.
The effective dose of melatonin for most adults is 0.1 to 0.5 milligrams, somewhere between 10 and 100 times less than what most products sell. This isn’t a fringe position; it’s well-supported in the research literature and has been for decades. We just collectively ignore it because higher doses sell better.
What melatonin actually is
Melatonin is a hormone produced by your pineal gland in response to darkness. It doesn’t cause sleep directly. It signals to your brain that it’s nighttime, which shifts your circadian clock and creates conditions conducive to sleep.
This is an important distinction. Melatonin is not a sedative. It’s a timing cue. Taking a massive dose doesn’t knock you out the way an antihistamine does. It just floods your receptors with a signal that should be a whisper.
The dose problem
A 1994 study by MIT’s Richard Wurtman, one of the researchers who first characterized melatonin’s effects in humans, found that doses as low as 0.1–0.3 mg were as effective as doses of 3mg or more for sleep onset, while producing more physiologically normal blood melatonin levels. Higher doses created supra-physiological peaks and extended the duration of elevated melatonin into daytime hours.
A 2022 systematic review in JMIR Mental Health echoed this. Low-dose melatonin (under 1mg) works for circadian-related sleep issues, but evidence for high doses is not stronger, and there are reasons to be cautious.
What too much melatonin might do
The short-term safety profile of melatonin is generally good. But there’s growing interest in the effects of chronically elevated melatonin on reproductive hormones, particularly in adolescents and people of reproductive age.
Melatonin interacts with the HPG axis, the hypothalamic-pituitary-gonadal axis that regulates sex hormones. Some animal research and limited human data suggest that chronic exposure to high doses may suppress LH and FSH, which regulate ovulation and testosterone production. The clinical significance in healthy adults isn’t settled, but it’s one reason researchers and some clinicians recommend using the lowest effective dose.
What melatonin is and isn’t good for
Melatonin is most effective for circadian disruption, including jet lag, shift work, and delayed sleep phase syndrome. In these cases, the timing of when you take it matters as much as how much you take. For jet lag moving eastward, taking 0.5mg at local bedtime for a few days after arrival is well-supported.
For general insomnia, meaning trouble falling or staying asleep driven by anxiety, lifestyle, or poor sleep hygiene, melatonin is less compelling. The underlying drivers aren’t a melatonin deficiency.
What to do instead
For jet lag or shift work, try 0.3–0.5mg taken at your new target bedtime. Low-dose products exist but require some searching, so check the supplement aisle more carefully or look for products marketed to children, which tend to have lower doses.
For chronic insomnia, the best-studied, most effective intervention is Cognitive Behavioral Therapy for Insomnia (CBT-I), which has better long-term outcomes than any sleep medication. Apps like Sleepio and Somryst have validated digital CBT-I programs. Your doctor may also be able to refer you to a sleep specialist.
For general sleep quality, sleep hygiene improvements like a consistent wake time, limiting evening light exposure, and a cooler bedroom temperature have reliable effects. These aren’t glamorous, but neither is lying awake at 2am.
The bottom line
Melatonin at low doses, used correctly for circadian timing issues, is a useful tool. The 10mg gummies are a marketing success story, not a clinical recommendation. Less is more, and in this case, much less is more.
