A Beginner’s Guide to Melatonin

Melatonin has been a buzzword for years, but what is it, exactly? Here, everything you need to know about this naturally occurring hormone and supplement.

by Cara Roberts Murez Health Writer

You may have heard about melatonin. This naturally occurring hormone is credited with everything from keeping your internal clock on track and helping you catch some ZZZs to reducing jet lag and easing anxiety about surgery.

Your body already makes melatonin, but sometimes, it doesn’t make enough of it. “Melatonin is secreted in darkness,” says Jennifer Martin, Ph.D., professor of medicine at the David Geffen School of Medicine at UCLA in Los Angeles and a member of the American Academy of Sleep Medicine Board of Directors. “When we’re exposed to light, it turns off melatonin production.”

Your melatonin levels aren’t static over the course of your life—they change as you age. “In young people, there’s no melatonin production during the day and levels are very high at night, so it's almost like an on-off switch,” Martin says. “As people age, there's more of a gradual increase and a gradual decline, and the peak levels of melatonin aren't quite so high.”

So what exactly is melatonin, and what are people so hyped up about it? Take a closer look at the role this hormone plays in your life.

What Is Melatonin?

In the center of your brain is the pinecone-shaped pineal gland, which really has one main job—producing melatonin. It works by both receiving and sending signals surrounding light and darkness in your environment. In response to those signals, it either makes melatonin (when it senses darkness) or shuts off production (when it senses light). This is exactly why it’s a bad idea to pick up your smartphone in the middle of the night if you can’t sleep. “The phone’s light will tell your brain to stop making melatonin and start the day,” Martin says.

This light-dark interplay is part of your body’s circadian rhythm, also called your internal clock, that affect such functions as body temperature, hormone release (melatonin is just one of many), and even digestion. Circadian arousal peaks in the evening, so most people are more awake and alert in the early evening than at any time throughout the 24-hour cycle, says David Neubauer, M.D., an associate professor of psychiatry and behavioral sciences at Johns Hopkins University School of Medicine in Baltimore and a sleep expert.

Melatonin for Sleep

Because of its direct relationship with circadian rhythms, melatonin may help improve some sleep-related conditions, including:

  • Jet lag. Research suggests that taking melatonin supplements may help reset your internal clock when traveling to different time zones. If you’re traveling from west coast to east and bedtime is earlier than you’re used to, try taking it at your new bedtime. If you’ve traveled west and bedtime is later than you’re used to, take it in the morning.

  • Circadian rhythm disorders. If you have an internal clock that’s misfiring, melatonin may help you adjust your sleep timing, though it can be difficult to figure out exactly when and what time of day to take melatonin supplements.

  • Delayed sleep-wake phase disorder. With this circadian rhythm disorder, people typically fall asleep sometime between 2 a.m. and 6 a.m. and tend to wake up between 10 a.m. and 1 p.m. Studies show melatonin may help you fall asleep about half an hour earlier.

  • Neurodevelopmental disorders. A 2019 review of clinical trials in the Journal of Child Neurology found melatonin to be effective for improving the ability to fall asleep and sleep duration in children with autism and other neurodevelopmental disorders.

Melatonin Health Benefits

Beyond regulating your internal clock, melatonin has beneficial properties that work in concert with the body to improve health. Here’s what we know so far:

Cancer Symptoms

Melatonin may help with the side effects of cancer treatments. One study found significant impact in sleep quality for postmenopausal breast cancer survivors. Another found that melatonin significantly decreased depression symptoms for three months after surgery in women who had breast cancer. Talk with you doc before taking any supplements.


A 2015 review of studies found that taking melatonin reduced anxiety in adults awaiting surgery because it has sedative and analgesic properties, in addition to helping regulate sleep, so it can have a calming influence.

Alzheimer’s Disease

One theory is that melatonin production decreases in people with Alzheimer’s, and that supplementation may help restore some sleep functions, but more research is needed. The American Academy of Sleep Medicine recommended against melatonin use by people with dementia in its 2015 guidelines.


Experts have even been studying whether this hormone may have an impact on viruses, such as Ebola and COVID-19, or their side effects. This is because melatonin has anti-inflammatory and antioxidant properties that may help fight infection.

Maximizing Your Natural Melatonin

Light sensitivity is a highly individual thing, and therefore how much melatonin you produce is unique to you. Some people easily fall asleep and may even have trouble staying awake before bedtime without the distraction of the computer or the TV. For them, it’s OK to keep those screens on a little later.

But if you’re very sensitive to light near bedtime, meaning you have a hard time falling asleep right after shutting off the TV, for example, it’s a good idea to start reducing light levels in your environment at least an hour before you plan to go to sleep. That means turning off all devices because those screens have the direct effect of keeping your brain awake.

It may also help to use an app that blocks blue light on your devices when they are in use—the blue light that they emit suppresses melatonin. Your phone, tablet, and/or computer might already have a built-in “night mode” setting that blocks blue light between certain hours. Check for it in the settings or preferences sections of your devices and enable it.

Another helpful step is switching to low color-temperature LED light bulbs that emit light from the red spectrum in your home. “You can search for ‘sleep bulbs’ in your favorite online store, and you’re likely to find examples of these bulbs that can be used in a bedroom,” Dr. Neubauer says.

When Your Own Melatonin Isn’t Enough

Sometimes, though, the body struggles to produce enough melatonin on its own. Melatonin supplements, available over the counter at pharmacies and health food stores, might help. You’re likely to find both “natural” and synthetic melatonin formulations. Though it can be derived from animals and microorganisms, the natural form also carries the risk of virus, so some doctors advise against it. The synthetic form of the hormone is considered to be relatively safe over the short term—its long-term safety hasn’t been determined.

Not sure whether the bottle you’re looking at is natural or synthetic melatonin? If the label doesn’t make it clear, ask the pharmacist. “People have to be aware that because it’s not an FDA-approved medication, it’s not subjected to the same standards as one would expect for a medication that you get prescribed by your doctor,” Martin says. “Companies make all kinds of claims about what it might do, but they’re not required to show the same level of proof that it's true.”

One study of 31 melatonin supplements and found in many cases, the amount of melatonin in the supplement didn’t match the amount listed on the label—some had less and some had considerably more. Also, many contained the hormone serotonin, which can have harmful side effects. One way to protect yourself is to look for supplements from brands that have been tested by an independent lab, such as ConsumerLab.com, USP (U.S. Pharmacopeia), and NSF International—look for one of their seals on the label.

The typical doses used in melatonin research have varied from 0.1 to 10 milligrams. Higher doses have not been shown to be any more effective than lower doses. In fact, a very high dose can stay in your body so long that it confuses your natural melatonin production. Never exceed the recommended amount on supplement labels. Start with a low dose, Dr. Neubauer advises, such as 0.5 mg. For most people, just this little bit has the desired effect.

With your doctor’s OK, try a melatonin supplement about two hours before bedtime. It doesn’t work well right at bedtime because your natural melatonin is already rising then, so there’s less opportunity for supplemental melatonin to have an impact. It’s also important not to take it just before or just after eating. Emerging evidence suggests that melatonin taken around mealtime can provoke an unwanted increase in glucose and insulin responses.

Melatonin Side Effects and Cautions

Long-term side effects of melatonin use in adults are unknown. Short-term side effects can include:

  • Headache

  • Dizziness

  • Sleepiness

  • Nausea

  • Low blood pressure

  • Confusion or disorientation

  • Abdominal cramps

  • Mild tremor

  • Feelings of depression

  • Mild anxiety

Some people may have an allergic reaction to melatonin. Also, don’t drive or use machinery within five hours of taking the supplement because of potential drowsiness. Women who are pregnant or breastfeeding should not take melatonin because its impact on the fetus and infant is not known. Supplemental melatonin may stay active for longer periods in older adults than in younger ones, which can cause daytime drowsiness. People of any age with jobs where sedation could compromise safety, including commercial drivers or airline pilots, should be especially cautious.

While apparent side effects in kids are considered minor over the short term, the long-term impact of this hormone on development, such as puberty and overproduction of another hormone called prolactin needed to make breastmilk, is unknown. Side effects are similar to those in adults, such as headache, dizziness, and drowsiness, and children may also experience agitation and increased bedwetting.

Melatonin Drug Interactions

Another reason to talk to your doctor before starting melatonin (or any new supplement) is the risk of drug interactions with other over-the-counter medications, prescriptions, and supplements you’re taking, as well as how it might affect any other medical conditions you have.

There’s a long list of potential drug interactions with melatonin, but the most important ones include:

  • Immunosuppressants

  • Seizure threshold-lowering drugs

  • Anticoagulants and antiplatelet drugs, herbs, and supplements

  • Anticonvulsants in neurologically disabled children

It can also worsen blood pressure for people on high blood pressure medication, affect sugar levels for people using diabetes drugs, cause excessive drowsiness by increasing melatonin levels for people on fluvoxamine, increase the side effects of melatonin in people taking contraception, and have a negative impact on people on cytochrome substrates.

If your best efforts to boost melatonin naturally don’t help or if you struggle with sleep three or more times a week and the problem goes on longer than three months, reach out to a sleep specialist. He or she will help determine if melatonin supplements are right for you and what dose to take, Martin says. This is also a good idea if you have other sleep-related issues like snoring, extreme sleepiness during the day, or any unusual behaviors while asleep.

Cara Roberts Murez
Meet Our Writer
Cara Roberts Murez

Cara Roberts Murez is a writer and editor based in Oregon. Her work has appeared in HealthDay, U.S. News & World Report, WebMD, and many other media outlets.