Can You Overdose On Melatonin?

Man awake staring at alarm clock

Cavan Images / Getty Images

Melatonin is a hormone your brain produces to control your sleep-wake cycle. This hormone can also be made synthetically and is available as a dietary supplement that can help you sleep.

Melatonin supplements come in the forms of pills, capsules, and liquids and can be effective in helping to control your sleep cycle.

Melatonin is also naturally occurring in fruits such as tomatoes, almonds, and oranges, but only in very small amounts. While research shows that melatonin can be an effective treatment for people who are having sleep troubles, it might not be for everyone. 

Melatonin's Role in the Body

The role of melatonin in our bodies is to regulate our wake and sleep cycle. Melatonin supplements are thought to mimic the effects of the naturally occurring hormone and can help improve your sleep. 

Melatonin Production

Your natural melatonin levels start to rise in the evening. It then peaks at night and dwindles in the morning. The season of the year might also affect your melatonin levels. During winter, your brain might produce melatonin later or earlier in the day than usual.

Melatonin production peaks at night and dwindles during the day when it’s bright out. This is because when it’s dark, our optic nerves signal the pineal gland in our brain to produce melatonin. 

Overexposure to bright light and blue light from screens can disrupt this melatonin production therefore disrupting your sleep pattern. Other things that may disrupt your melatonin production include: 

  • Aging
  • Jet lag
  • Not exercising regularly 
  • Delayed sleep-wake phase disorder
  • Working night shifts 

Uses

Melatonin supplements are usually recommended for people who find it difficult to fall asleep at night or sleep through the night. It’s typically recommended for people dealing with the following issues.

Insomnia

Melatonin is most commonly used by people who have insomnia. However, there are mixed results on its effectiveness to treat the disorder.

While some people with chronic insomnia report no improvement when using melatonin, others say it makes them sleep longer and better. The synthetic hormone has proven to be more effective in treating insomnia in the elderly than in younger people.

Sleep Disorders in Children

Melatonin can help children who find it difficult to fall asleep or sleep through the night. The supplement helps children to fall asleep more quickly and increases their sleep time.

Children with autism and Asperger’s syndrome often suffer from sleep disorders. Many children with these conditions report not being able to fall asleep at night or sleep through the night.

Jet Lag

People who travel across different time zones often experience jet lag. Melatonin can be very effective in reducing or preventing jet lag from occurring.

It is typically recommended for people flying across five or more time zones, especially when going in an eastern direction. But it can also be recommended for people flying across 2 to 4 different time zones if they usually experience jet lag during these trips.

Non-24-Hour Sleep-Wake Disorder

Non-24-hour sleep-wake disorder is a condition that throws people’s sleep cycles out of alignment. Their sleep and wake up times tend to move later and later each day, the longer the condition goes untreated.

Visually impaired people most commonly report having this condition, but sighted people may develop it too. Melatonin is a potential treatment for this condition, particularly in blind people.

Night Shift Workers

The sleep patterns of night shift workers are often disrupted and this causes low quality of sleep. Melatonin helps to improve the duration and quality of their sleep.

It is typically recommended for night shift workers to take melatonin at the end of a shift or a couple of hours before your bedtime. This supplement shouldn’t be taken if you are about to drive or operate heavy machinery.

Effects of Daily Melatonin Use

Studies show serious adverse affects and toxicity of melatonin is relatively rare. However, more long-term human research needs to be conducted to conclusively prove this.

What this means, is that it's relatively safe to use melatonin daily. However it’s advisable to only do this for a short period. While no current research points at the toxicity of using melatonin long term, you can have side effects when you take it at too high a dose.

Most doctors recommend a dosage of 1 to 3 milligrams (mg). In some people, an overdose of melatonin may cause excessive sleepiness while in others it might produce the opposite of the desired effect and trigger over alertness.

Signs of an overdose include nausea, diarrhea, headaches, and anxiety. In some cases, some people might also experience a spike in their blood pressure. 

Where to Buy Melatonin

In the United States, melatonin is available as a dietary supplement and not a medication which means it’s not as closely regulated as most medications by the Food and Drug Administration (FDA).

When shopping for melatonin supplements it’s important to be careful. Some brands have their dosages listed incorrectly while others contain other chemicals you might not want to consume.

While melatonin is sometimes recommended for children with sleep disorders there isn’t enough research to establish its safety for children. Even though it’s readily available over the counter and doesn’t need a prescription, it’s always best to speak to a doctor or medical professional before giving your child melatonin.

Before Taking

Melatonin is available as an over the counter treatment (OTC). This means it can easily be bought at your local pharmacy without a doctor’s prescription.

If your deal with the following conditions, it's important to speak to a doctor before taking melatonin:

  • People who are epileptic 
  • If you suspect you might be at risk of experiencing an allergic reaction 
  • Older people 
  • People with dementia 
  • Pregnant or breastfeeding women 

How to Take Melatonin

Taking high doses of melatonin is not recommended by most medical experts. Most over-the-counter melatonin supplements contain between 0.1 to 12 milligrams of melatonin.

According to the American Academy of Pediatrics (AAP) doses above 3 to 6 mg of melatonin shouldn’t be given to children. 

The National Health Service (NHS) also advises that you take melatonin supplements an hour or two before your bedtime. Taking it too early or too late might only further disrupt your wake-sleep cycle instead of helping to regulate it. 

Side Effects 

Even though taking melatonin is relatively safe its use might sometimes result in some mild side effects. Side effects of taking melatonin are similar in children and adults. Taking melatonin can sometimes cause the following side effects: 

  • Anxiety 
  • Dizziness 
  • Headache 
  • Fatigue 
  • Nausea
  • Daytime drowsiness

If you experience swelling, difficulty breathing, or hives when using melatonin you might be having an allergic reaction to it and should see a doctor at the emergency room.

Was this page helpful?
6 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Olde Rikkert MGM, Rigaud A-SP. Melatonin in elderly patients with insomniaZ Gerontologie und Geriatrie. 2001;34(6):491-497. doi:10.1007/s003910170025

  2. Herxheimer A, Petrie KJ. Melatonin for the prevention and treatment of jet lag. Cochrane. Published April 22, 2002.

  3. National Organization of Rare Disorders. Non-24-Hour Sleep-Wake Disorder. Rare Disease Database.

  4. National Center for Complementary and Integrative Health. Melatonin: What You Need to Know. Updated October 2019.

  5. Bruni O, Alonso-Alconada D, Besag F, et al. Current role of melatonin in pediatric neurology: Clinical recommendationsEuropean Journal of Paediatric Neurology. 2015;19(2):122-133.

  6. Melatonin. University of Michigan: Michigan Medicine. Updated May 28, 2019.