The Powerful — and Surprising — Health Benefits of Melatonin

The molecule of darkness. The hormone of rest and rejuvenation. The ultimate multitasker. These are just some of the ways nutrition scientist Deanna Minich, PhD, CNS, IFMCP, describes melatonin.

“When most people think of melatonin, they think of sleep,” says Minich. “They are unaware of its many other functions.”

Melatonin is a crucial part of the sleep cycle, but its role does not end there, she notes. “It’s a potent antioxidant, it regulates the mitochondria, it can stimulate the immune system, and it’s a circadian signal.”

And there’s more. Melatonin helps control temperature, blood pressure, and the gut microbiome. It also supports neurogenesis and protects nerve cells, which help repair and detoxify the brain.

“Melatonin is called nature’s most versatile biological signal,” Minich says.

Melatonin is a hormone found throughout nature, made by plants, animals, fungi, and even bacteria. In humans, most circulating melatonin is produced in the pineal gland from the amino acid tryptophan. The pineal gland responds to evening darkness by releasing melatonin into the bloodstream, telling the body it’s time for sleep.

On average, the pineal gland generates between 0.1 and 0.9 milligrams of melatonin per day. The gut mucosa contains about 400 times more, but most of it stays within the gastrointestinal tract. There it helps protect the gut lining, reduce inflammation, and regulate gut motility and the microbiome.

Melatonin is also synthesized in the eyes, skin, and various other glands and organs. At these sites, it helps modulate the immune system, repair tissue, and prevent oxidative stress and inflammation.

Our bodies start producing melatonin when we’re about 3 months old, with levels ramping up from infancy to adolescence and peaking ­before puberty. Production then declines and can drop significantly by the time we reach our 50s.

“This is when we find ourselves in ‘melatonipause’ — a term I love because it syncs up with the decline of so many other hormones,” Minich says.

In addition to aging, melatonin production is influenced by illness, diet, and environmental factors such as exposure to artificial blue light at night. Some medications and a lack of exposure to sunlight can also impact levels.

There’s a lot to know about this crucial molecule and the many ways it supports our health. Let’s explore some of melatonin’s more unexpected roles.

How Does Melatonin Fight Free-Radicals?

Free radicals are highly reactive molecules. They’re a natural byproduct of metabolism, but the body also produces them in response to nutritional deficiencies as well as ­exposure to ultraviolet radiation, pollution, certain medications, and toxins. There are ­always free radicals circulating in our bodies, but an excess of them can lead to cellular damage, chronic diseases, and accelerated aging.

Antioxidants neutralize harmful free radicals. Some, such as vitamins C and E, come exclusively from dietary sources. Others, such as glutathione, are mostly produced in the body (the superhero antioxidant, glutathione, battles toxicity, chronic disease, and premature aging. Find out what makes it so powerful at “8 Ways to Boost Glutathione.”)

Melatonin is an antioxidant that’s both produced in the body and ­derived from dietary sources — though we make more than we can get from food.

“Melatonin is a direct scavenger. It gobbles up free radicals like Pac-Man.”

“Melatonin is a direct scavenger. It gobbles up free radicals like Pac-Man,” says Russel Reiter, PhD, one of the world’s leading melatonin experts. “Vitamin E and vitamin C are go-to antioxidants, but they don’t compare to melatonin.”

Several factors make melatonin a potent antioxidant. First, unlike vitamins C and E, it’s both water- and fat-soluble, so it can move freely through all types of cells and tissues, offering protection throughout the body.

Second, because melatonin is produced within our ­cellular ­mitochondria, where free radicals are created, it can quickly neutralize troublemakers ­before they have a chance to do damage.

Finally, melatonin and its meta­bolites can scavenge up to 10 free radicals, while most antioxidants can vanquish only one.

Minich compares melatonin to a set of Russian nesting dolls. “When melatonin gets one free radical, it changes into the next doll down, which gets another free radical, et cetera. All of a sudden, 10 dolls later, it’s cleaned up quite a number of bad things in the body.”

Does Taking Melatonin Affect Circadian Rhythm?

Many of us mistake melatonin for a seda­tive, but it doesn’t induce sleep directly. Instead, it more broadly supports sleep by helping regulate our body’s internal clocks — the circadian rhythms.

In addition to the sleep–wake cycle, these rhythms govern hormone production, ­metabolism, immune function, and body temperature.

“Melatonin helps open the ‘sleep gate’ by lowering our core body temperature and preparing the brain for synchronizing with the peripheral clocks throughout the body,” Minich explains. “As it becomes dimmer and darker at night, our melatonin goes up, our core body temperature comes down, and we get this signal to head for bed.”

While melatonin supplements won’t knock you out on their own, they can assist if you struggle to fall asleep, especially if your internal clocks are dysregulated by shift work or travel. A ­Cochrane review published in 2002 concluded that 0.5 to 5 mg of melatonin is “remarkably ­effective in preventing or reduc­ing jet lag,” particularly for those traveling east.

Timing matters. If melatonin is taken early in the day, the review authors note, it can cause sleepiness too early and further confuse the body’s internal clock.

Some studies suggest that supplement­ing with 3 mg of melatonin can help ­menopausal women who struggle with nighttime hot ­flashes regulate their body temperature.

Does Melatonin Help Reduce Inflammation?

During the COVID-19 pandemic, melatonin received heightened attention for its capacity to both help fight infections and reduce inflammation. A paper published in Clinical Nutrition ESPEN in 2021 listed it among the key preventive and therapeutic nutraceuticals for COVID, along with zinc, selenium, and vitamins C and D.

Melatonin can stimulate cytokine production to help the body fight off invading viruses, bacteria, or other pathogens, notes John ­Lieurance, ND, DC, in his book Melatonin: Miracle ­Molecule. It can also help slow down cyto­kine production when the body needs to reverse or prevent potential inflammatory damage.

“Being chronically underslept will increase the likelihood of illness and chronic inflammation.”

“It is this dual action of melatonin on the immune system that has been of particularly great interest to scientists,” Lieurance writes. It makes melatonin especially valuable in treating conditions like COVID, where the potential overreaction of the ­immune system — known as a cytokine storm — can be as damaging as the infection itself.

Because inflammation is managed in part by optimal sleep, melatonin’s role in promoting sleep is key, says Samantha McKinney, RD, who helps lead nutrition education at Life Time. “Being chronically underslept will increase the likelihood of illness and chronic inflammation.”

Emerging research suggests that symptoms associated with inflammatory autoimmune conditions, such as multiple sclerosis, may be eased with melatonin supplementation. This is most likely due to the hormone’s anti-­inflammatory properties and its ability to reduce oxidative stress and regulate the gut microbiome.

How Does Melatonin Affect Mitochondria?

The pineal gland produces most of the melatonin that circulates through the body and regulates circadian rhythms. Another type of melatonin is produced inside our cells, by mitochondria. “Melatonin and mitochondria go together,” says Minich.

Known as the power­houses of our cells, mito­chondria produce energy in the form of adenosine triphosphate, which fuels virtually everything our cells do (learn more about these essential molecules and how to keep yours healthy at “The Care and Feeding of Your Mitochondria.”)

Because of their role in energy production and cellular health, mitochondria also influence how we age. Dysfunctional mitochondria can contribute to cellular senescence — the loss of a cell’s ability to divide and function properly. Senescent cells release inflammatory signals, driving much of the chronic inflammation and tissue damage associated with age-related decline.

Mitochondrial dysfunc­tion has been linked to neurodegenerative diseases like dementia, Alzheimer’s, Parkinson’s, and multiple sclerosis. Poor mitochondrial health can also contribute to type 2 diabetes, cardio­vascular disease, and psychiatric disorders.

The presence of melatonin and other antioxidants in mitochondria is key to preventing such dysfunction and damage. “Now we know that melatonin is synthesized in the mitochondria, and it seems to be very efficient at protecting mitochondria from damage,” Reiter says.

How Does Melatonin Affect Your Immune System?

The body’s immune system protects us from harmful viruses and bacteria. It also identifies and destroys mutated human cells that can ­develop into cancer. Melatonin ­increases the level of circulating natural killer cells, which bolsters the immune system’s ability to ward off diseases ­including colds and cancer.

As of 2024, more than a hundred studies on PubMed pointed to the potential of melatonin in supporting treatment for a range of cancers, ­including breast, prostate, and bladder. ­Melatonin supplementation, which has been used for decades in ­patients under­going chemotherapy, “seemed to sensitize the cancer cells to the treatment,” Minich says.

Is Melatonin Healthy for the Brain?

Thanks in part to its sleep-supportive properties, melatonin plays a critical role in brain health.

“One of the main ways sleep protects the brain is by supporting the glymphatic system, which helps detoxify the brain nightly,” McKinney explains. As we sleep, this system flushes out metabolic waste products that contribute to neurodegenerative diseases such as Alzheimer’s.

Melatonin is an important molecule in this “brainwashing” process, as Reiter calls it. As a sleep-regulating hormone, it enhances deep, restorative sleep — when the glymphatic system is most active.

Melatonin’s antioxidant powers protect brain cells from oxidative stress and inflammation, both of which accelerate cognitive decline. Because it’s both ­water- and fat-soluble, it can cross the blood-brain barrier and directly neutralize harmful free radicals in the brain.

Melatonin’s presence in the brain can lead to cognitive benefits, especially for people with neurodegenerative conditions like ­Parkinson’s. It may even help with neuropathic pain and depression risk, Minich says.

She sometimes calls melatonin the ­“molecule of consciousness” because it can enhance the vividness of dreams, and she notes that long-term meditators have been found to have higher levels of melatonin compared with nonmeditators.

Given melatonin’s many positive roles, it’s only natural to wonder about your own levels. Melatonin can be measured in the blood, saliva, and urine, but Reiter says these metrics are of limited utility.

“It’s very difficult to find your own melatonin levels, because you have to get the nighttime values,” he explains. “If you go to your physician and ask to be tested, we’ll all have low melatonin because daytime levels are always low.”

“It’s very difficult to find your own melatonin levels, because you have to get the nighttime values. If you go to your physician and ask to be tested, we’ll all have low melatonin because daytime levels are always low.”

Our levels can also vary day to day, month to month, and season to season.

“It’s better to look at symptoms,” Minich says. Some indicators of insufficient melatonin include:

• abnormal fatigue
• inflammatory conditions
• chronic stress
• gut dysbiosis
• frequent colds or infections
• disrupted sleep patterns

You can also review your cur­rent circumstances. Stress, inconsis­tent sleep patterns, and nighttime light exposure can all suppress melatonin production.

And age matters: Around 40, natural production of the hormone begins to decline more steeply.

Paying attention to your symptoms and circumstances — and supporting melatonin production by maintaining a consistent sleep schedule, limiting blue-light expo­sure at night, and spending time in natural daylight — can help you reap melatonin’s many benefits.

Strategies for Supplementing With Melatonin

Melatonin is widely available as a supplement, with doses usually far exceeding what our bodies make naturally ­— even when production is at its peak. Circumstances such as cancer treatment warrant taking high doses under a physician’s care, but for most of us, less is more, says Deanna Minich, PhD, CNS, IFMCP.

“We produce less melatonin as we get older, so I think a physiological dose of 0.3 to 1 milligram is reasonable to ‘patch the gap,’” she says.

Research supports her suggestion. An older MIT study determined that 0.3 mg of melatonin was more effective at treating insomnia than the typical drugstore dose of 3 mg. It also found that the higher dose elevated circulating melatonin levels during the day, causing a hangover effect.

For jet lag, however, the reverse is true. Studies suggest that a dose of 5 mg helps people fall asleep faster and sleep better than 0.5 mg but that more than 5 mg had no additional benefit.

For daily use, Minich recommends starting with 0.3 mg, taken about 30 to 60 minutes before bedtime. If you feel groggy in the morning, you may need to take it earlier, about two to three hours before bed.

She also recommends opting for plant melatonin over synthetic versions. A study published in Molecules in 2021 found the plant-derived molecule in the brand Herbatonin to be more anti-inflammatory and better at free-radical scavenging. (Minich is the chief science officer for Symphony Natural Health, which produces Herbatonin and whose cofounder helped author the study.)

Melatonin supplements aren’t for everyone. They can interact with medications, including blood thinners, blood-pressure drugs, and immunosuppressants. And anyone who is pregnant, breastfeeding, or managing a hormone-related or autoimmune disorder should speak with their healthcare provider before use.