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What Happens If You Take Too Much Melatonin? (Effect on Sleep)

by Dale Cudmore | Updated: Feb 04, 2022

There’s a lot of evidence showing that melatonin can help insomnia in many cases, although there are exceptions.

But more is often not better.

The optimum dosage of melatonin is relatively low, and taking too much can either make your sleep quality worse, or even be dangerous.

What’s the Ideal Dosage of Melatonin For Sleeping?

There’s no one universal ideal dosage for everyone, so some experimenting can be needed.

However, there are plenty of studies that can give us a good range to start with.

The following table is from a meta-analysis of melatonin studies and shows that most studies give subjects from 0.1-5 mg of melatonin. Note that some studies do go up to 10 mg (1).

Even in the studies that use multiple dosages, there’s rarely any difference in its effect on sleep quality between the groups.

With all that being said, certain individuals may do best with a dosage on the lower or higher end of that range. That could vary based on weight, overall size, and sensitivity to melatonin.

SummaryThe ideal dosage for melatonin is likely around 5 mg, depending on the individual. Most products usually contain 3-5 mg per pill, and instruct you to take 1 because that’s all that’s needed.

What If A Low Melatonin Dosage Isn’t Working?

Melatonin often makes it easier to fall asleep in situations where someone is exposed to light stimulation right until they go to bed.

But it’s not a fix for every type of sleep issue (e.g. sleep anxiety, too much caffeine, etc.).

So if a low dosage of melatonin isn’t doing much, more is not necessarily going to help, and could actually hinder sleep.

With that being said, testing out 10 or 20 mg is safe in most cases. Obviously if you have other medication that could interact, this is something that needs to be cleared by a doctor.

SummaryWhile trying a slightly higher dosage of melatonin can help in some cases, it’s not particularly likely to help if a lower dosage isn’t already having a significant effect.

Melatonin Overdose: How Much is Safe?

For the most part, research shows that melatonin is quite a safe substance, which explains why it’s available over the counter.

However, there aren’t too many studies that look at very high dosages or high dose melatonin usage for a long time.

It’s possible that it could take years for toxicity to reach a dangerous threshold, but no studies that I could find have looked at a long period of continuous melatonin usage (2).

One study did have patients take 1,000 mg (or about 200 times the recommended amount) and saw significant adverse effects (3).

Even in a report of melatonin overdose case studies, the side effects were relatively mild in healthy people (4):

While changes in pituitary hormones were observed, no toxic effects were reported.

Hypotension can certainly be dangerous for some people with existing health concerns.

SummaryWhile taking more melatonin is rarely effective, even large doses are generally well-tolerated, at least in the short term.

Summary: Can You Take Too Much Melatonin?

In theory, there’s some limit where taking too much melatonin will have severe health effects.

However, that limit is very high.

Studies have shown that taking several times the dosage typically recommended on a melatonin product is unlikely to cause health issues in most people.

At the same time, a higher dosage doesn’t improve sleep quality in most cases, and can actually make it worse. It can also lead to daytime drowsiness the next day.


  1. Meta-Analysis: Melatonin for the Treatment of Primary Sleep Disorders
  2. Evidence for the efficacy of melatonin in the treatment of primary adult sleep disorders
  3. The effects of oral melatonin on skin color and on the release of pituitary hormones
  4. An Upsurge in Melatonin Overdose,Severe Hypotension in an Adolescent After a Melatonin Overdose

Medical Disclaimer: The information on is not intended to be a substitute for physician or other qualified care. We simply aim to inform people struggling with sleep issues about the nature of their condition and/or prescribed treatment.

About the authorDale is the founder of Snooze University and a sleep researcher. I overcame my sleep issues and now I'd like to help you do the same by summarizing the latest sleep studies for you.