The COVID-19 outbreak is a rapidly evolving situation. CDC health information   NIH research information

Nccih Logo

Melatonin: What You Need To Know

Woman yawing
© iStock

What is melatonin and how does it work?

Melatonin is a hormone that your brain produces in response to darkness. It helps with the timing of your circadian rhythms (24-hour internal clock) and with sleep. Being exposed to light at night can block melatonin production.

Research suggests that melatonin plays other important roles in the body beyond sleep. However, these effects are not fully understood.

Melatonin dietary supplement can be made from animals or microorganisms, but most often they’re made synthetically. The information below is about melatonin dietary supplements.

What are the health benefits of taking melatonin?

Melatonin supplements may help with certain conditions, such as jet lag, delayed sleep-wake phase disorder, some sleep disorders in children, and anxiety before and after surgery.

Does melatonin help with cancer symptoms?

Studies of the effect of melatonin supplements on cancer symptoms or treatment-related side effects have been small and have had mixed results.

Keep in mind that unproven products should not be used to replace or delay conventional medical treatment for cancer. Also, some products can interfere with standard cancer treatments or have special risks for people who’ve been diagnosed with cancer. Before using any complementary health approach, including melatonin, people who’ve been diagnosed with cancer should talk with their health care providers to make sure that all aspects of their care work together.

Can melatonin help with insomnia?

People with insomnia have trouble falling asleep, staying asleep, or both. When symptoms last a month or longer, it’s called chronic insomnia.

According to practice guidelines from the American Academy of Sleep Medicine (2017) and the American College of Physicians (2016), there’s not enough strong evidence on the effectiveness or safety of melatonin supplementation for chronic insomnia to recommend its use. The American College of Physicians guidelines strongly recommend the use of cognitive behavioral therapy for insomnia (CBT-I) as an initial treatment for insomnia.

Does melatonin work for shift workers?

Shift work that involves night shifts may cause people to feel sleepy at work and make it difficult to sleep during the daytime after a shift ends.

According to two 2014 research reviews, studies on whether melatonin supplements help shift workers were generally small or inconclusive.

  • The first review looked at 7 studies that included a total of 263 participants. The results suggested that (1) people taking melatonin may sleep about 24 minutes longer during the daytime, but (2) other aspects of sleep, such as time needed to fall asleep, may not change. The evidence, however, was considered to be of low quality.
  • The other review looked at 8 studies (5 of which were also in the first review), with a total of 300 participants, to see whether melatonin helped promote sleep in shift workers. Six of the studies were high quality, and they had inconclusive results. The review did not make any recommendations for melatonin use in shift workers.

Is it safe to take melatonin?

For melatonin supplements, particularly at doses higher than what the body normally produces, there’s not enough information yet about possible side effects to have a clear picture of overall safety. Short-term use of melatonin supplements appears to be safe for most people, but information on the long-term safety of supplementing with melatonin is lacking.

Also keep in mind:

  • Interactions with Medicines

    • As with all dietary supplements, people who are taking medicine should consult their health care providers before using melatonin. In particular, people with epilepsy and those taking blood thinner medications need to be under medical supervision when taking melatonin supplements.
  • Possible Allergic Reaction Risk

    • There may be a risk of allergic reactions to melatonin supplements.
  • Safety Concerns for Pregnant and Breastfeeding Women

    • There’s been a lack of research on the safety of melatonin use in pregnant or breastfeeding women.
  • Safety Concerns for Older People

    • The 2015 guidelines by the American Academy of Sleep Medicine recommend against melatonin use by people with dementia.
    • Melatonin may stay active in older people longer than in younger people and cause daytime drowsiness.
  • Melatonin Is Regulated as a Dietary Supplement

    • In the United States, melatonin is considered a dietary supplement. This means that it’s regulated less strictly by the Food and Drug Administration (FDA) than a prescription or over-the-counter drug would be. In several other countries, melatonin is available only with a prescription and is considered a drug.
  • Products May Not Contain What’s Listed on the Label

    • Some melatonin supplements may not contain what’s listed on the product label. A 2017 study tested 31 different melatonin supplements bought from grocery stores and pharmacies. For most of the supplements, the amount of melatonin in the product didn’t match what was listed on the product label. Also, 26 percent of the supplements contained serotonin, a hormone that can have harmful effects even at relatively low levels.

Is melatonin safe for children?

In addition to issues mentioned above, there are some things to consider regarding melatonin’s safety in children.

Melatonin supplements appear to be safe for most children for short-term use, but there aren’t many studies on children and melatonin. Also, there’s little information on the long-term effects of melatonin use in children. Because melatonin is a hormone, it’s possible that melatonin supplements could affect hormonal development, including puberty, menstrual cycles, and overproduction of the hormone prolactin, but we don’t know for sure.

Possible melatonin supplement side effects reported in children have usually been mild and have included:

  • Drowsiness
  • Increased bedwetting or urination in the evening
  • Headache
  • Dizziness
  • Agitation.

What are the side effects of melatonin?

A 2015 review on the safety of melatonin supplements indicated that only mild side effects were reported in various short-term studies that involved adults, surgical patients, and critically ill patients. Some of the mild side effects that were reported in the studies included:

  • Headache
  • Dizziness
  • Nausea
  • Sleepiness.

The possible long-term side effects of melatonin use are unclear.

Tips To Consider

  • Remember that even though the FDA regulates dietary supplements, such as melatonin, the regulations for dietary supplements are different and less strict than those for prescription or over-the-counter drugs.
  • Some dietary supplements may interact with medicines or pose risks if you have medical problems or are going to have surgery.
  • If you’re pregnant or nursing a child, it’s especially important to see your health care provider before taking any medicine or supplement, including melatonin.
  • If you use dietary supplements, such as melatonin, read and follow label instructions. “Natural” doesn’t always mean “safe.” For more information, see Using Dietary Supplements Wisely.
  • Take charge of your health—talk with your health care providers about any complementary health approaches you use. Together, you can make shared, well-informed decisions.

For More Information

NCCIH Clearinghouse

The NCCIH Clearinghouse provides information on NCCIH and complementary and integrative health approaches, including publications and searches of Federal databases of scientific and medical literature. The Clearinghouse does not provide medical advice, treatment recommendations, or referrals to practitioners.

Toll-free in the U.S.: 1-888-644-6226

tty (for deaf and hard-of-hearing callers):

1-866-464-3615

Website: https://nccih.nih.gov/

Email: info@nccih.nih.gov (link sends e-mail)

PubMed®

A service of the National Library of Medicine, PubMed® contains publication information and (in most cases) brief summaries of articles from scientific and medical journals. For guidance from NCCIH on using PubMed, see How To Find Information About Complementary Health Approaches on PubMed.

Website: https://pubmed.ncbi.nlm.nih.gov/

NIH Clinical Research Trials and You

The National Institutes of Health (NIH) has created a website, NIH Clinical Research Trials and You, to help people learn about clinical trials, why they matter, and how to participate. The site includes questions and answers about clinical trials, guidance on how to find clinical trials through ClinicalTrials.gov and other resources, and stories about the personal experiences of clinical trial participants. Clinical trials are necessary to find better ways to prevent, diagnose, and treat diseases.

Website: https://www.nih.gov/health-information/nih-clinical-research-trials-you

National Heart, Lung, and Blood Institute (NHLBI)

The NHLBI Health Information Center provides information to health professionals, patients, and the public about heart, lung, and blood diseases and sleep disorders and accepts orders for publications.

P.O. Box 30105
Bethesda, MD 20824-0105

Toll-free in the U.S.: 301-592-8573, or dial 7-1-1 for access to free Tel

Website: https://www.nhlbi.nih.gov/

Email: nhlbiinfo@nhlbi.nih.gov (link sends e-mail)

Key References

Acknowledgments

NCCIH thanks D. Craig Hopp, Ph.D., and David Shurtleff, Ph.D., NCCIH, for their review of the 2019 update of this publication.

This publication is not copyrighted and is in the public domain. Duplication is encouraged.

NCCIH has provided this material for your information. It is not intended to substitute for the medical expertise and advice of your health care provider(s). We encourage you to discuss any decisions about treatment or care with your health care provider. The mention of any product, service, or therapy is not an endorsement by NCCIH.

Last Updated: October 2019