The Danger of Treating Melatonin as a Supplement

The human body naturally produces the hormone melatonin, which plays an important role in sleep. Critically, melatonin helps regulate the sleep-wake cycle by signaling the body when it's time for sleep.

Many people are familiar with melatonin as a widely available supplement promoted as a product to improve sleep problems. Available in doses of 1 to 10 milligrams, melatonin is marketed as a dietary supplement and, as such, does not need premarket approval by the Food and Drug Administration (FDA), so verifying vendor and source quality is vital.

That may be a slight cause for concern, as the amount of melatonin found in over-the-counter (OTC) melatonin supplements often varies from what is listed on the label, according to a study published in the February 2017 edition of Journal of Clinical Sleep Medicine. The study indicated melatonin content did not meet within a 10 percent margin of the label claim in more than 71 percent of supplements. Actual melatonin content ranged from 83 percent less to 478 percent more than the amount declared on the label, with lot-to-lot differences within a particular product varying by as much as 465 percent.

These discrepancies are particularly alarming given the sharply rising interest in melatonin. A 2022 research letter published in the Journal of the American Medical Association indicated a fivefold increase in melatonin usage between 1999 and 2018. These trends were similar for women and men and across all age groups. Melatonin is indeed a safer alternative to prescription sleep aids that may become addictive, but accurate dosage is critical to make it a truly healthy choice.

What we know about melatonin

Melatonin is not like pain medication. It is a hormone that when ingested, interacts with other hormones in the body. In its natural form, melatonin is manufactured by the pineal gland, the neuroendocrine gland within the brain, located deep at the midline of the brain just behind the thalamus.

The melatonin hormone drives homeostasis and other vital processes such as regulation of the body's circadian rhythm system, which is intimately related to healthy sleep patterns and the circadian rhythm system. Circadian rhythm encompasses the physical, mental and behavioral changes which follow a 24-hour cycle, natural processes that respond primarily to light and dark. Melatonin levels in the body gradually start rising in the evening and upon reaching certain threshold levels, begin to induce sleep. The reversal of this process as daylight occurs creates wakefulness.

Melatonin is not like pain medication—it is a hormone that when ingested, interacts with other hormones in the body.

As an artificial supplement, melatonin is effective in treating sleep disorders that relate to the body clock. Many people self-administer melatonin to treat acute insomnia, a sleep disorder that makes it difficult for someone to fall asleep or stay asleep for one night to a few weeks. In cases of chronic insomnia, sleep is affected for at least three nights per week for three months or more. In these cases, a sleep specialist can prove more helpful than at-home solutions.

In fact, Muhammad Rishi, M.D., a sleep doctor at Mayo Clinic Health System in Eau Claire, Wisconsin, explained that problems arise when melatonin is marketed as a cure-all for sleep issues.

"If you ask the supplement industry, they will tell you that [it helps] everything, from headaches to insomnia," he said. "But really, if you talk about what there is evidence for and what the American Academy of Sleep Medicine recommends its usage for, it certainly has a role in treating circadian rhythm disorders, advanced sleep phase and delayed sleep phase disorders. It can also be used to treat jet lag. And there may be a role in treating acute insomnia in certain situations. However, at the American Academy of Sleep Medicine, we do not think that there's any role for melatonin in the treatment of chronic insomnia."

The dosage depends on the need

Melatonin dosages can vary significantly contingent on the disorder that's being treated as well as the formulation of the supplement.

"It depends on why you're taking the medicine," Rishi advised. "It's a medicine and that's why you can't have a one-size-fits-all approach. For example, if it's taken for a delayed sleep phase, you want to take it several hours before bedtime. If you're taking it for jet lag, it has to be taken during your journey. You have to realize that this is a hormone and it interacts with other hormones. That's how it works, so having some [medical] knowledge is important. It has to be done under the supervision of a physician [who can] prescribe it and [explain] how to use it."

The general consensus in online discussions among regular melatonin users is that lower doses have very few aftereffects. For people taking longer-acting formulations of melatonin, feeling sleepy during the day is a common effect.

Emerging research suggests that some caution needs to be taken with long-term use of melatonin. Like all medications, it is important to consult a physician when administering to children, as recent research shows more understanding is needed on the interactions of melatonin on growth and sexual maturation processes, particularly with long-term use. Experts are still uncovering the exact extent and mechanisms of those interactions. Speak to your doctor if you notice any changes in your or your child's health.

Take it and do your own research

The primary concern with melatonin is the continued lack of conclusive research on its use and implications.

It's important to conduct individual research before deciding to keep taking melatonin as your sole medicinal strategy, according to Mahyar Etminan, a pharmacologist and researcher at the University of British Columbia. If you decide to take melatonin, take it as directed and consult your physician if you have questions or notice continued sleep problems.

"[Try] taking it for a couple of nights," Etminan said. "If it's too much—and you'll know if you're experiencing side effects—lower the dose. If you fall asleep without any side effects, that's probably the right dose."

He suggested looking out for common side effects such as drowsiness, irritability, confusion and alterations to the body's circadian rhythm. Etminan also recommended speaking to your primary doctor or a pharmacist before taking melatonin and starting to monitor it for any side effects.

The research on melatonin and its effectiveness (or lack thereof) is concerning. Rishi believes this is a problem because melatonin, classified as a dietary supplement, is regulated by the FDA as food and doesn't undergo the same regulatory process as a pharmaceutical drug.

Both Etminan and Rishi encourage people interested in taking melatonin to do their own research. Most importantly, both recommended involving a medical practitioner or pharmacist in any decision involving melatonin and being aware that melatonin serves as a Band-Aid rather than a long-term solution to sleep problems.

Editor's note: These statements have not been evaluated by the Food and Drug Administration. Our medical experts advise that you consult with your primary healthcare provider before you begin using a supplement. This information is not intended to diagnose, treat, cure or prevent disease.