Melatonin: benefits, dosage, and side effects

You’ve probably heard that melatonin supplements can help you get some shut-eye. But did you know that this popular dietary supplement has been linked to other potential health benefits?

Read on to learn more about the possible beneficial effects of melatonin, how much you should take, and some of the side effects that can occur with supplementation.

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Your body naturally makes melatonin in the pineal gland of your brain. Often called the sleep hormone, melatonin is the main influencer on your body’s circadian rhythm or internal clock. Its release increases in response to darkness, signaling your body that it’s time to get some shut-eye (Masters, 2014).

In the United States, melatonin is sold as an over-the-counter dietary supplement. Dietary supplements are in a distinct category, separate from drugs, and therefore aren’t regulated or approved by the Food and Drug Administration (FDA).

Sleep disorders are conditions that affect how much or how well you sleep. For example, insomnia (trouble falling asleep or staying asleep) is one of the most common sleep disorders. 

Most prescription treatments for insomnia and other sleep disorders have several downsides. For example, zolpidem (Ambien) can be addictive and cause dangerous side effects like sleep-walking or sleep-driving. So, many people are turning to melatonin as a natural sleep aid.

Most research supports that melatonin supplements are safe. But, melatonin’s benefits on sleep seem to be modest at best. So, melatonin might help you sleep a little bit better or longer, but most people won’t see dramatic improvements.  

A meta-analysis of 19 clinical studies of sleep disorders showed that melatonin supplements could help people fall asleep sooner, but only by about seven minutes. However, the supplement may improve overall sleep quality. With that said, more research on taking melatonin for sleep disorders is needed to reveal its long-term benefits (Ferracioli-Oda, 2013).

There is stronger evidence to suggest that Melatonin may help improve sleep for specific groups of people, such as (NCCIH, 2021; Savage, 2021; Masters, 2014):

• Shift workers

• People with circadian rhythm disorders

• Sleep disorders in children with an autism spectrum disorder or ADHD

• Older adults with insomnia

• People with sleep problems related to Alzheimer’s disease

• Women who have survived breast cancer (Chen, 2014)

Jet lag occurs when your body’s internal clock is thrown off by traveling across time zones. It takes your body a few days to naturally adjust, but in the meantime, you may feel groggy, have headaches, and struggle to fall asleep or stay awake when you want to.

There’s some evidence that taking a melatonin supplement may help to shorten that jet-lagged feeling. Taking melatonin before bedtime may help you adjust your sleep-wake schedule in preparation for travel. It’s recommended to take melatonin to help you fall asleep closer to the target bedtime of your destination at least two days before departure  (Lee, 2017). 

Some research shows that taking melatonin may help if you have seasonal depression or anxiety symptoms in certain situations.

Seasonal depression, also known as seasonal affective disorder (SAD), is depression related to changes in the season. Symptoms of depression tend to start at the same time each year as fall turns to winter and ease up in the spring. It is thought that SAD has something to do with the reduced exposure to natural light that happens in winter (Lewy, 2006).

A small study compared the effects of melatonin capsules to a placebo in people with SAD. Low doses of melatonin were given in the morning or afternoon, up to 0.3 mg per day. After three weeks, people who took melatonin had reduced SAD symptoms compared to those who took a placebo (Lewy, 2006). 

But, a recent review of melatonin for SAD was not conclusive (Nussbaumer-Streit, 2019). If you think you have seasonal depression, it’s best to talk to a healthcare professional about what might help.

Some research suggests that melatonin can help with anxiety symptoms. Researchers have studied the use of melatonin for a particular anxiety-inducing situation: surgery. Undergoing a surgical operation can be scary, and most people feel anxious beforehand. 

Research shows that melatonin, given before surgery, helps to ease anxiety more effectively than a placebo (which contains no active ingredient). It is unknown whether this anxiety-reducing effect may apply to other situations (Madsen, 2020).

Much of the research on melatonin’s effects beyond being a sleep aid has been limited to test tubes, animals, and small groups of people. When it comes to scientific research, these studies aren’t considered the strongest type of evidence. 

Some cell studies have shown potential anticancer benefits of melatonin, such as antioxidant and anti-inflammatory effects, which may help protect cells’ genetic material from damage. (This matters because genetic damage and mutations can sometimes lead to cancer (Talib, 2021)). However, it’s important to keep in mind that bigger studies with more people are necessary to confirm these potential benefits. 

Several studies suggest that melatonin may enhance the efficiency of chemotherapy drugs or help relieve some of their side effects (Talib, 2021). A 2020 clinical study in people undergoing chemotherapy for breast cancer showed that taking melatonin may help with things like sleep quality, cognitive function, and depressive symptoms (Palmer, 2020).

To be safe, if you’re receiving chemotherapy or other cancer treatments, check with your healthcare provider before taking any dietary supplements, including melatonin.

Melatonin supplements are sold over-the-counter in various strengths and forms, such as tablets, capsules, and gummies. Some formulations are timed-release or extended-release, meaning that they are designed to have longer-lasting effects. 

There’s no standard dosage for melatonin, but the usual dose ranges from 0.1 mg to 10 mg and may be taken up to two hours before bedtime (Savage, 2020). It is best to follow the labeled dosing instructions on the melatonin supplement.

Older adults (55 years and above) may have better results with low-dose, immediate-release melatonin formulations, such as 0.1 mg to 0.3 mg. This dose closely mimics the level of the body’s natural melatonin production, which may decline with age (Vural, 2014). 

Melatonin supplements are generally recognized as safe, and typical doses don’t usually lead to side effects. 

Drowsiness is the most common “side effect," but it is also the usual intended effect (for trouble sleeping). Other possible side effects, particularly with higher-than-usual doses of melatonin, may include (Savage, 2021; van Geijlswijk, 2010):

• Headaches

• Nausea

• Stomach upset

• Rash

• Nightmares or vivid dreams

• Daytime drowsiness the next day

• Mood changes

• Reduced appetite

• Dizziness

• Feeling cold

Melatonin supplements may not be safe for everyone—it isn’t known if melatonin supplements are safe to take with alcohol or during pregnancy—and the information in this article is not meant to replace personalized medical advice from a medical professional. 

It is best to talk to a healthcare professional before taking dietary supplements like melatonin if you’re being treated for any medical conditions, such as epilepsy, as there could be drug interactions. 

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Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

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Current version

November 22, 2021

Written by

Patricia Weiser, PharmD

Fact checked by

Felix Gussone, MD

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About the medical reviewer

Felix Gussone, MD, Ro

Felix Gussone is a physician, health journalist and a Manager, Medical Content & Education at Ro.