Melatonin plays several major roles in maintaining a healthy immune system: sleep regulation, powerful and unique antioxidant, and its effectiveness at raising Glutathione. This page will also provide information on where this hormone is produced, how much naturally occurs in our bodies, how it is depleted, what foods have it, and considerations for supplementation.

Pineal gland

Melatonin, known chemically as N-acetyl-5-methoxytryptamine, is a hormone secreted by the pineal gland located at the base of the brain that helps regulate sleep and wake cycles. This hormone is a derivative of the neurotransmitter serotonin and the amino acid tryptophan.


Our bodies have their own internal clocks that help regulate the natural cycle of sleeping and waking hours (circadian rhythm) by controlling the production of melatonin. Usually, the levels of this hormone begin to rise in the mid- to late evening, remain high for most of the night, and then decline in the early morning hours. According to the Society for Light Treatment and Biological Rhythms, approximately 5-25 mcg of melatonin are secreted into the blood stream of healthy young and middle-aged men at night time.

Natural production is greatly affected by light. That is why during the shorter days of the fall and winter months, melatonin production may start earlier in the day. This change can lead to symptoms of seasonal affective disorder (SAD), or winter depression, when some people feel more tired and they need more sleep. Natural melatonin levels decline gradually after the age of thirty. Some elderly people produce very small amounts of it or none at all.


Melatonin is a powerful antioxidant that can cross cell membranes, cross the blood-brain barrier, and it plays a role in stimulating other antioxidants - this makes it a truely unique antioxidant. It is considered more powerful than vitamins C, E and A, because it is soluble in both fat and water and can enter cells that vitamins cannot. Unlike other antioxidants, it does not undergo redox cycling, which is the ability of a molecule to undergo repeated reduction and oxidation and regain its antioxidant properties (in other words, it cannot be recycled). That is why it is referred to as a terminal antioxidant.

Melatonin has been shown to effectively raise Glutathione levels in many tissues, such as the brain, liver, blood serum and muscles.

Read the abstracts of clinical trials linking melatonin to Glutathione production.

Each antioxidant plays specific roles within our bodies. One of the roles melatonin plays is in the protection of nuclear and mitochondrial DNA. Of course this requires some explanation first. DNA stands for deoxyribonucleic acid. It is found in the nucleus and in the mitochondria of the cell. DNA is the genetic material that is responsible for determining who and what we are. Nuclear DNA is the DNA found in the nucleus of the cell. Mitochondrial DNA is found within the cell; mitochondria are structures within cells that convert the energy from food into a form that cells can use. Click here for more information on Mitochondrial DNA. This is a lot of in-depth information about melatonin, but it is presented to stress how important of a role it plays in protecting our health.

DNA repair is a vital role in our health. The oxidative stress producing free radicals damages our DNA. The DNA is surprisingly resilient but it can function properly when damaged only to a certain degree. At some point, the damage becomes too severe and the cell starts duplicating itself uncontrollably. Our body recognizes this as a foreign cell (cancer or tumor) and attacks it. If our body's attack is successful we are never aware it occured. But if it is not successful we develop cancer. So, melatonin protecting DNA before the damage gets to this severe point is vitally important to the success of immune system in keeping our bodies cancer and tumor free.

As an antioxidant melatonin is a potent scavenger of free radicals. It has been studied extensively for the treatment of cancer, immune system disorders, Alzheimer's disease, autism, cardiovascular disease, and depression.


Most of us know that we heal the fastest when we sleep: why? The answer to this question is not a straightforward answer. But a big part of the answer has to do with glutathione, antioxidants and melatonin.

Antioxidants eliminate free radicals and in cases like melatonin and glutathione, antioxidants can also repair DNA. So what is the relationship of these three things and how do they affect the healing process when we sleep?

To start, when we lack an antioxidant or are low on specific antioxidants, glutathione takes on their role (job, so to say) of eliminating free radicals. This tends to deplete glutathione supplies in the body, which then inhibits or slows down all the other roles that glutathione plays in our body – detoxification, DNA repair, recycling other antioxidants, transfer of energy from mitochondria to the cell, food for the immune system and as an immune system regulator.

When melatonin is produced, as an antioxidant it frees up glutathione (this is proven clinically). With the freeing up of glutathione, glutathione is then free to perform its other roles. Two of the most important roles are food for the immune system and toxin removal. The healing process is greatly inhibited by the presence of pathogens and toxins. So while this answer is not direct, by following the path of antioxidants, melatonin and glutathione, and understanding the interactive role they have with one another, we can see how melatonin production increases glutathione and in turn speeds the healing process.


New York at night Of great interest are the studies about the effect of light pollution on the production of melatonin and as a result, the impact on the metabolism, immune function, endocrine balances and the development of cancers.

Light pollution is the brightening of the sky at night by artificial lightning of highways, streets, malls, stadiums, homes, etc., also called urban sky glow. Retinal ganglion cells responsible for detecting light and suppressing melatonin production are most sensitive to blue/violet light.

The 2007 review published in the Journal of Pineal Research states that human exposure to low-level incandescent lightning for only 39 minutes suppresses melatonin levels upto 50%. As we stated above, melatonin stimulates Glutathione synthesis. Constant light exposure leads to melatonin deficiency which leads to decreased tissue Glutathione peroxidase activity and the promotion of oxidative stress.

Current evidence suggests, as noted in the review The dark side of light, exposure to the high levels of artificial light at night may play a role in cancer risk. Studies have indicated that melatonin exerts a direct effect on tumor growth and proliferation, and the increased risk of cancer was observed in patients with the brightest bedrooms. Multiple studies have documented a link between night shift work and an increased incidence of breast cancer.

Read the full text of this review here: "The dark side of light at night: physiological, epidemiological, and ecological consequences" by Kristen J. Navara and Randy J. Nelson. The Ohio State University, Columbus, OH.

Another factor that reduces melatonin production is certain drugs: non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Motrin, Advil) or naproxen (Naprosyn, Aleve); beta-blocker blood pressure medications such as atenolol (Tenormin) or metoprolol (Lopressor, Toprol); and medications that reduce levels of vitamin B6 in the body (such as birth control pills, hormone replacement therapy, loop diuretics, hydralazine, or theophylline).


The use of melatonin supplements became quite popular some 15+ years ago as a way of treating insomnia, jet lag, SAD, chronic cluster headaches, sleep regulation in people who work evening or night shifts and sleep-wake cycle training in blind people (because they do not have the perception of light and darkness).

Melatonin supplements can be of animal/bovine origin (made from ground pineal glands of cows or sheep) and synthetic (man-made):

  1. Melatonin of animal or bovine origin, even though called natural, is very unsafe because it can be infected with bacteria or viruses. Due to these risks this type of melatonin supplement is no longer available over the counter.

  2. Like all unnatural products, the use of the synthetic form of melatonin has side effects and should not be used without consulting a healthcare professional, even though this supplement is available without prescription in the USA. Many countries, for example in Europe, prohibit over the counter melatonin and other hormone supplements.

    Daily dosages of synthetic melatonin vary greatly depending on the age and the medical condition of a person and typically are in the range of 0.25-10 milligrams (the most common doses are 2-5 mg) to be taken 30-120 minutes before bedtime.

    Even the smallest dose of synthetic melatonin is much higher than the amount normally circulating in the blood stream at night time. Since human blood contains approximately 5-25 mcg of melatonin at night, even the smallest available dose of 0.25 mg of synthetic melatonin is 10-50 times (!) higher than what is normally found in the blood.

    The studies have also shown that the highest doses of 10 mg/day (400 times higher than normal) do not produce better results than 0.25 mg/day. The most commonly used doses of 2-5 mg/day are thus 80-200 times higher than normally found in the blood. It is always good to remember that melatonin is a hormone and like with all hormones such excessive amounts may produce undesirable health results.

    Side effects from synthetic melatonin may include: abnormal heart rhythms, high blood pressure, confusion, difficulty concentrating, fatigue, dizziness, sleepiness, irritability, headache, mood changes, depression, hormonal effects, hypothermia, itching, heaviness in the head, seizures, sleepwalking, stomach problems, vivid dreams, morning grogginess, and reduced sperm count.

    Synthetic melatonin is absolutely prohibited to be used during breastfeeding and is unadvisable to be used by pregnant women, children, people with autoimmune diseases, liver diseases, kidney diseases, epilepsy, stroke, and by those taking other drugs or consuming alcohol. Studies have shown that these side effects are rare in healthy people with short-term use of no more than three months, taking not more that 3 mg of synthetic melatonin a day.


The best source of melatonin, which is not commonly known, a truly natural one, is found in food - tart (sour) cherries in amounts that are able to have a positive effect on health.

Research has also shown that melatonin is present in many other common foods, however, in very small quantities.

Check out our overview of FOODS WITH MELATONIN

sleeping child

Can melatonin be used for children?

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  • On average 5-25 micrograms (mcg) of melatonin circulate in the blood of healthy young and middle-aged men at night time according to the Society for Light Treatment and Biological Rhythms.

  • The most common doses of synthetic melatonin are 2-5 milligrams (mg) which is 80-200 times more (!) than naturally circulates in the blood.

    (1 mg = 1,000 mcg)

  • Synthetic melatonin supplement is not a natural sleep aid - it is a man-made hormone designed to mimic melatonin produced by the brain.

  • Since melatonin is a hormone, long-term (more than 3 months) use of synthetic melatonin supplements may have a negative impact on your health. For this reason, in Europe melatonin is available only with prescription.

  • Tart (sour) cherries are the only food that has been scientifically proven to have melatonin in significant amounts, enough to produce possitive results in the body.

  • 1 oz. of tart cherry juice concentrate contains 4910 ng (4.91 mcg) of melatonin - about the minimum amount of what circulates in the blood of males at night time (this number is according to the Michigan growers).

  • It has also been scientifically proven that melatonin ingested from the diet is absorbed and enters the blood circulation, after which it is capable of binding to sites in the brain and other tissues.

  • Melatonin has been shown to effectively raise Glutathione levels in many tissues, such as the brain, liver, blood serum and muscles. That is why it is so very important to have a good night sleep for at least 7-8 hours.

  • Levels of melatonin produced in the body decline with age.

  • Sleeping with a night light or light coming into your bedroom from outside dramatically decreases production of melatonin - upto 50% within only 39 minutes of light exposure.


glutathione molecule

Learn about Glutathione (GSH)

Studies: Melatonin Increases
Glutathione Levels

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"The Dark Side Of Light At Night" -
What Depletes Melatonin?


Study: presence of melatonin
in tart cherries.

Cherry Nutrition Report




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