Melatonin is a hormone that promotes sleep and normal circadian rhythms. In addition, melatonin plays a role in enhancing immune function and performs various antioxidant activities such as protecting against mitochondrial oxidative stress.

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    Promoting Sleep Onset

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    Circadian Rhythm

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What is Melatonin?

Melatonin is a hormone common to animals, plants, and microbes. In plants, melatonin protects the plant from a variety of bacteria, fungi, and viruses, as well as influences reproductive development and circadian rhythms.1,2

In humans, it is produced by converting tryptophan to serotonin to melatonin and is especially important for promoting sleep and maintaining a healthy sleep-wake cycle. When light decreases in the evening, melatonin is released from the pineal gland, a small endocrine gland at the base of the brain.

Melatonin levels are highest in children and commonly decrease with age. Factors that can disrupt normal melatonin secretion include:

  • Stress
  • Odd working hours
  • Shifts in day-night cycles associated with travel across multiple time zones
  • Artificial light in the evening

Melatonin can be synthetically produced and used to supplement natural melatonin production in the body. If used in appropriate amounts, melatonin supplementation does not affect our natural production of this hormone.

Young pensive doctor is skeptical about x-ray image on the monitor at dark office.
Regularly working at night can disrupt normal melatonin secretion


Molecular Formula: C13H16N2O2
Scientific name: Mel, N-acetyl-5-methoxytryptamine
Known for: Supporting sleep
Fun fact: Melatonin regulates circadian rhythms not only in humans, but also in plants!
Good for: Promoting sleep onset and recalibrating circadian rhythm
Key Properties & Actions: recalibrates circadian rhythm, initiates sleep, immunomodulatory, antioxidant

Benefits of Melatonin and How It Works

Supports Sleep Onset and Normal Sleep Cycles

The release of melatonin initiates a tide of sedating hormones and neurotransmitters that flow into the brain and promote sleep. Note that melatonin is a sleep initiator, not a sleep sustainer. Once sleep becomes established each night, melatonin levels naturally decline making way for cortisol, the primary hormone responsible for helping us wake up and get into the day. Melatonin taken at night may be helpful for rebalancing a disrupted circadian rhythm.

circadian rhythm line graph, normal and disrupted
In a normal healthy circadian rhythm, cortisol levels are highest in the morning. Working late hours, travelling across several time zones, and physical inactivity are just a few factors that can make it hard to fall asleep when the evening comes. The result can be a disrupted circadian rhythms and where cortisol levels peak later in the day.

Immune Enhancement

Melatonin is thought to enhance immune function through a variety of pathways. While research is still ongoing, it appears that melatonin exhibits some immunomodulatory activity, stimulating immune function when it’s depressed and calming immune function when it’s excessive. This activity supports emerging evidence showing potential benefit of melatonin for immune issues ranging from autoimmunity to infections to the natural decrease in immune function common among older adults.3,4

Antioxidant Activity

Melatonin, when naturally secreted from the pineal gland, is a powerful free-radical scavenger and antioxidant. It works with other antioxidants to improve the overall effectiveness of each antioxidant. It has also been shown to be twice as active as vitamin E (another antioxidant) and a better protector against mitochondrial oxidative stress.5

How to Use and Dosing

Herbal supplements and sleep practices that balance normal circadian rhythms help promote the natural secretion of melatonin. In addition, supplemental melatonin can be used to help restore normal sleep cycles that have been disrupted.

Melatonin supplements are best taken 30-60 minutes before bedtime. This timing supports normal onset of sleep by mimicking the body’s natural sleep initiation processes.

The dosage of melatonin should be limited to physiologic doses, or around 1.5 mg. In general, high doses of oral melatonin (>5 mg) and time-released melatonin do not mimic the normal secretion of melatonin in the body and should be avoided. Note that some products contain much higher doses of melatonin which can actually be counterproductive causing morning grogginess and potentially interfere with natural melatonin production.

For a better effect that supports sleep at multiple levels, consider using melatonin supplements in combination with other supplements and herbs like passionflower, lemon balm, bacopa, GABA, L-theanine, and ashwagandha.

After normal sleep cycles are reestablished, supplemental melatonin should be discontinued to prevent tolerance from occurring. Clinical studies that support efficacy of melatonin suggest it’s best use primarily as a short-term dietary supplement for dealing with issues like occasional sleeplessness, jet lag, and disruption of normal day-night schedules.

For jet lag, combining the use of melatonin at night with bright light exposure during the morning and dim light in the evening before bed can help reduce symptoms.6

There are also numerous food sources of melatonin that have been shown to modestly increase blood levels of the hormone. Some of these foods include tart cherries, oats, bananas, seaweed, turkey, tofu, and milk.7,8


Always check with your healthcare practitioner before using melatonin if you have a medical condition or are taking medications. Avoid use with calcium channel blockers, benzodiazepines, or methamphetamine.

Precautions & Side effects

The safety of using melatonin supplementation during pregnancy is unknown, so it’s recommended to avoid it during this time.

People with significant depression should consult with their healthcare provider before using melatonin.

A 2017 study published in the Journal of Clinical Sleep Medicine investigated the contents of 30 commercial melatonin supplements. Many of the products did not contain the quantity of melatonin that they claimed to and about a quarter contained serotonin which was not indicated on the product label and can have harmful effects at low levels.9 This is a good reminder about the importance of purchasing melatonin, and other supplements from a trustworthy company with thorough quality controls.


This information is intended only as general education and should not be substituted for professional medical advice. Any mentioned general dosage option, safety notices, or possible interactions with prescription drugs are for educational purposes only and must be considered in the context of each individual’s health situation. Use this information only as a reference in conjunction with the guidance of a qualified healthcare practitioner.

1. Moustafa-Farag M, Almoneafy A, Mahmoud A, et al. Melatonin and Its Protective Role against Biotic Stress Impacts on Plants. Biomolecules. 2020;10(1). doi: 10.3390/biom10010054
2. Arnao MB, Hernández-Ruiz J. The Physiological Function of Melatonin in Plants. Plant Signal Behave. 2006;1(3):89. doi: 10.4161/psb.1.3.2640
3. Carrillo-Vico A, Lardone PJ, Álvarez-Sánchez N, Rodríguez-Rodríguez A, Guerrero JM. Melatonin: Buffering the Immune System. Int J Mol Sci. 2013;14(4):8638. doi: 10.3390/ijms14048638
4. Srinivasan V, Maestroni GJM, Cardinali DP, Esquifino AI, Perumal SP, Miller SC. Melatonin, immune function and aging. Immun Ageing. 2005;2:17. doi: 10.1186/1742-4933-2-17
5. Reiter RJ, Mayo JC, Tan D-X, Sainz RM, Alatorre-Jimenez M, Qin L. Melatonin as an antioxidant: under promises but over delivers. J Pineal Res. 2016;61(3):253-278. doi: 10.1111/jpi.12360
6. Malhotra S, Sawhney G, Pandhi P. The Therapeutic Potential of Melatonin: A Review of the Science. Medscape Gen Med. 2004;6(2). Accessed August 2, 2021.
7. Kuhn M. Herbal Therapy & Supplements: A Scientific and Traditional Approach. Lippincott; 2001.
8. Salehi B, Sharopov F, Fokou PVT, et al. Melatonin in Medicinal and Food Plants: Occurrence, Bioavailability, and Health Potential for Humans. Cells. 2019;8(7). doi: 10.3390/cells8070681
9. Erland LAE, Saxena PK. Melatonin Natural Health Products and Supplements: Presence of Serotonin and Significant Variability of Melatonin Content. J Clin Sleep Med JCSM Off Publ Am Acad Sleep Med. 2017;13(2):275-281. doi: 10.5664/jcsm.6462

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