What is Melatonin?


If you are having trouble feeling tired at the times you would like to sleep, disruption to your circadian rhythm and melatonin levels may be to blame.

The circadian rhythm (1) operates on a 24-hour schedule and regulates when we feel tired and when we feel awake. Melatonin (2), a hormone naturally created by the pineal gland in the brain, plays a major role in this process by making us sleepy in response to darkness.

Synthetic melatonin (3) can be taken in tablet or liquid form as a sleep aid supplement and is available without a prescription. It is also available as a patch, so it may be absorbed by the skin, and as a suppository. We discuss how melatonin supplementation works, if it might help with your sleep troubles, potential side effects, and dosage.

What Is Melatonin?

Melatonin is often called the sleep hormone because we tend to feel sleepy after it is released. This hormone is naturally produced by the body on a daily basis. A person's melatonin level is generally low throughout the day, then increases in the evening and peaks in the middle of the night. Light suppresses the release of melatonin, which is why we normally feel tired after dark.

Can Melatonin Improve Sleep?

Synthetic melatonin is designed to impact when a person feels tired and how tired they feel. Although melatonin supplements are not approved as a sleep aid by the U.S. Food and Drug Administration (FDA), research suggests melatonin may improve sleep for some people.


Adults often take melatonin for the following sleep issues:

  • Insomnia: Insomnia (4) refers to when a person has trouble falling asleep and/or trouble staying asleep throughout the night. Doctors may recommend melatonin for insomnia, although research suggests people with chronic insomnia might not benefit (5) from taking melatonin. Instead, cognitive behavioral therapy for insomnia (CBT-I) is the preferred first-line treatment.
  • Jet Lag: Jet lag occurs when a person travels across several time zones and is still accustomed to feeling tired and awake according to the time in their original time zone (6). Melatonin supplements may offer some relief from jet lag symptoms.
  • Shift Work: People who work at night or on a rotating schedule often have trouble feeling alert at work and sleeping when they would like. Research studies have produced mixed results about the effectiveness of melatonin supplementation for shift work sleep problems.
  • Delayed Sleep-Wake Phase Disorder (DSWPD): People with delayed sleep-wake phase disorder have an unusual sleep schedule that is misaligned with daylight hours, causing them to stay up very late at night and sleep in until late morning or early afternoon. Melatonin supplements may help these individuals shift to an earlier bedtime.

Researchers continue to study the effect of melatonin supplementation for other disorders, such as cancer, heart problems, digestive disorders, and mental illnesses.


Researchers have had some success in using melatonin supplements to treat sleep problems in children, particularly children with accompanying conditions such as autism, attention deficit hyperactivity disorder (ADHD), or eczema. Studies show taking melatonin before bed may help these children fall asleep faster and stay asleep longer, though more research is needed. Parents should consult with their pediatrician if they are considering melatonin supplements for their children.

Side Effects of Melatonin

Melatonin supplements are generally considered safe for short-term use and do not pose a high risk of serious side effects. The most common documented side effects (7) include:

  • Daytime sleepiness
  • Headaches
  • Dizziness
  • Feeling cold
  • Nausea

More research is needed to gain a clearer picture of melatonin’s potential side effects, especially when used for longer periods of time. With regards to using melatonin supplements for children, there are some concerns that melatonin may interfere with puberty, as it is a hormone.

Melatonin Dosage

The correct dose of melatonin may vary depending on the situation. Experts generally recommend taking between 0.5 and 5 milligrams (8) per night, about an hour before sleeping. It may be best to start with a lower dose and gradually increase it, under the guidance of your doctor.

How to Choose a Melatonin Supplement

Because the FDA does not regulate supplements, it is a good idea to do your research before purchasing a melatonin supplement. Consider looking for a brand that has undergone third-party testing through organizations such as United States Pharmacopeia (USP).

Researchers have found that many melatonin supplements on the market are not accurately labeled. A 2017 study conducted in Canada found that the melatonin content (9) varied by more than 10% in 71% of the supplements tested, and some samples contained almost five times more melatonin than claimed. Moreover, some supplements also contained unlisted substances such as serotonin (10), another neurotransmitter that comes with potential side effects of its own.

When to Talk to Your Doctor

Although melatonin supplements are available without a prescription, you should talk to your doctor before trying these supplements for the first time. This is especially important if:

  • You are currently taking other medications
  • You are pregnant or breastfeeding
  • You have another medical condition
  • You are interested in giving melatonin to your child
  • You believe you might have an underlying sleep disorder

Your doctor can provide advice on whether melatonin is safe for you to take. They can also help identify and treat any underlying sleep disorders or other conditions that might be interfering with your sleep.


+ 10 Sources
  1. 1. Accessed on September 19, 2021.https://www.nigms.nih.gov/education/fact-sheets/Pages/circadian-rhythms.aspx
  2. 2. Accessed on September 19, 2021.https://pubmed.ncbi.nlm.nih.gov/23996364/
  3. 3. Accessed on September 19, 2021.https://pubmed.ncbi.nlm.nih.gov/30521244/
  4. 4. Accessed on September 19, 2021.https://medlineplus.gov/insomnia.html
  5. 5. Accessed on September 19, 2021.https://www.nccih.nih.gov/health/melatonin-what-you-need-to-know
  6. 6. Accessed on September 19, 2021.https://pubmed.ncbi.nlm.nih.gov/32066704/
  7. 7. Accessed on September 19, 2021.https://pubmed.ncbi.nlm.nih.gov/31722088/
  8. 8. Accessed on September 19, 2021.https://www.merckmanuals.com/professional/special-subjects/dietary-supplements/melatonin
  9. 9. Accessed on September 19, 2021.https://pubmed.ncbi.nlm.nih.gov/27855744/
  10. 10. Accessed on September 19, 2021.https://pubmed.ncbi.nlm.nih.gov/31424752/

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