Most adults should start with 0.5 to 1 mg of melatonin, taken 30 to 90 minutes before bedtime. That’s far less than what most supplements on store shelves contain, but research consistently shows that low doses work as well as high ones for helping you fall asleep. A Mayo Clinic review found that a dose as small as 0.5 mg seems just as effective as 5 mg or higher.
The reason lower works as well as higher has to do with how melatonin actually functions in your body, and why taking too much can backfire.
Why Less Melatonin Often Works Better
Melatonin isn’t a sedative. It’s a hormone your brain already produces each evening as light fades, signaling your body that it’s time to wind down for sleep. When you take a supplement, you’re topping up that signal. Your body only needs a small nudge to get the message.
The sleep receptors that respond to melatonin can become desensitized when flooded with more hormone than they’re designed to handle. Research published in The American Journal of Managed Care describes this effect: exposure to unnaturally high levels of melatonin in the bloodstream can cause these receptors to stop responding normally. In practical terms, taking too much melatonin can actually make your sleep worse over time, not better. The European Food Safety Authority has recommended a ceiling of 0.3 to 1 mg as the maximally effective dose range, noting that this is where the strongest evidence for reducing the time it takes to fall asleep was established.
Dosage by Age Group
Adults Under 65
Start at 0.5 mg. If that doesn’t help after a week, move to 1 mg, then up to 3 mg if needed. Most people won’t benefit from going higher. Melatonin has a short half-life of 20 to 40 minutes, meaning half the dose leaves your body quickly. In total, it stays active in your system for about four to five hours. One study found that even after a 10 mg dose, blood levels of melatonin dropped to zero within five hours. So timing matters more than size: take it 30 to 60 minutes before you want to sleep.
Adults Over 65
Older adults typically produce less melatonin naturally, which is one reason sleep quality often declines with age. But that doesn’t mean you need a large dose to compensate. In fact, older adults are more susceptible to receptor desensitization, so sticking to 0.3 to 1 mg is especially important for this group. Higher doses are more likely to cause next-day grogginess or disrupt the natural sleep cycle rather than support it.
Children
There are no official dosing guidelines for children. Most children who respond to melatonin do well on 0.5 to 1 mg taken 30 to 90 minutes before bed. Even children with ADHD or other conditions that affect sleep rarely need more than 3 to 6 mg. The American Academy of Pediatrics urges caution: short-term use appears relatively safe, but there’s limited data on how long-term melatonin use might affect growth and development, particularly during puberty. Between 2012 and 2021, poison control centers received more than 260,000 reports involving children and melatonin, largely due to unsupervised access to bottles that look like candy.
What Melatonin Actually Helps With
Melatonin is best suited for problems related to sleep timing, not sleep quality. The American Academy of Sleep Medicine recommends it as a treatment option for jet lag and shift work disorder, situations where your internal clock is out of sync with when you need to sleep. For jet lag, taking 0.5 to 1 mg at your destination’s bedtime can help reset your rhythm faster.
For chronic insomnia, the picture is different. The AASM specifically recommends against using melatonin as a treatment for ongoing insomnia in adults. If you’ve struggled with sleep for months, the first-line approach is cognitive behavioral therapy for insomnia (CBT-I), a structured program that retrains your sleep habits and thought patterns. Melatonin may serve as a short-term bridge, but it’s not the long-term fix for true insomnia.
The Label Problem
One of the biggest practical issues with melatonin is that the pill you’re taking may not contain what it says on the bottle. A study highlighted by the American Academy of Sleep Medicine found that more than 71% of melatonin supplements tested fell outside a 10% margin of their labeled dose. Actual melatonin content ranged from 83% less than advertised to 478% more. Even different batches of the same product varied by as much as 465%.
Perhaps more concerning, 26% of the supplements tested contained serotonin, a neurotransmitter that is far more tightly regulated as a pharmaceutical ingredient and has no business being in an over-the-counter sleep aid. Because melatonin is classified as a dietary supplement in the United States, the FDA does not review it for accuracy or purity before it hits shelves. If you’re going to take melatonin, choosing a brand that carries a third-party testing seal (such as USP or NSF) reduces your risk of getting an inaccurate dose.
Side Effects and Drug Interactions
At low doses, melatonin is generally well tolerated. The most common side effects are next-morning drowsiness, headache, dizziness, and nausea. Some people, especially children, notice increased urination at night.
Melatonin does interact with several categories of medication. If you take blood thinners, combining them with melatonin may increase your risk of bleeding. People on blood pressure medication should be cautious, as melatonin can affect blood pressure regulation. Anticonvulsant medications may become less effective with melatonin use, which is particularly relevant for children with neurological conditions. Any sedating medication, including certain antidepressants and anti-anxiety drugs, can produce compounded drowsiness when paired with melatonin. The antidepressant fluvoxamine is a notable example: it dramatically increases melatonin levels in the bloodstream, potentially causing excessive sedation. Hormonal birth control can have a similar amplifying effect.
A Practical Starting Plan
If you’ve never taken melatonin before, here’s a straightforward approach:
- Start at 0.5 mg. This is closer to what your body produces naturally and less likely to overwhelm your receptors.
- Take it 30 to 60 minutes before bed. Melatonin works fast but wears off within four to five hours, so timing it right matters more than taking a larger dose.
- Increase slowly if needed. Move to 1 mg after a week, and up to 3 mg only if lower doses have no effect. Going above 5 mg offers no proven additional benefit for most people.
- Use it short-term. A few weeks for jet lag or a temporary schedule disruption is the sweet spot. If sleep problems persist beyond that, the issue is likely something melatonin alone won’t solve.
Finding a 0.5 mg tablet can take some hunting, since most drugstore options start at 3, 5, or even 10 mg. Some brands sell 1 mg tablets that are scored for easy splitting. That small dose, taken consistently at the right time, is where the evidence points for most people.