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More than 20 million Americans take melatonin supplements, spending between $200 million and $350 million each year. Depending on who you ask, melatonin is either just another hormone or a medical miracle. According to some supporters melatonin can conquer insomnia, prevent jet lag, battle cancer, rejuvenate your sex life and slow aging. All of this for only $4 to $8 per bottle. Unfortunately, there's no reputable evidence to back up any of these claims.

What is Melatonin?

Melatonin is a hormone made by the pineal gland, a tiny pine cone-shaped gland deep within your brain. It is not an herb. As the sun sets your pineal gland goes to work, releasing increasing amounts of melatonin into your blood stream. Melatonin release gradually slows then stops between 2 a.m. and 4 a.m. For this reason, melatonin is sometimes known as the "night hormone."

What does Melatonin do in the body?

Melatonin's effects aren't well understood; however, it is though that melatonin may play a role in many body processes. Your blood vessels, ovaries, gastrointestinal system and brain all have cells that are specially equipped to utilize melatonin. This is one reason melatonin is claimed by some to have such a wide range of health benefits. Studies show one influence melatonin may have involves sleep. In most humans, the time period in which the pineal gland releases melatonin coincides with the hours you typically sleep.

Does melatonin help with sleep?

There is significant evidence that links the hormone melatonin to circadian sleep cycles in humans. It has been suggested that in situations where the body's melatonin concentration is reduced (advancing age) or the normal circadian cycle is disrupted (jet lag, shift work, blind patients), melatonin supplementation may improve both sleep duration and quality.

Because many people at times have difficulty sleeping, doctors have explored melatonin as a possible sleep aid. Several studies have found taking 1 to 2 milligrams (mg) a day may help improve the quality and duration of sleep in some people.

However, it appears melatonin supplements may help only the small number of insomniacs who have a melatonin deficiency. Melatonin has also been explored as a way to prevent jet lag. Some studies suggest you may be able to gradually move your bedtime ahead or back by taking small doses of melatonin (often less than 1 mg) at different intervals during the day. That may make it easier to adjust once you arrive at your destination. However, other studies have found that melatonin doesn't help jet lag or may make it worse.

Studies done thus far have had small numbers of test subjects and have not been conducted for very long periods of time.


Most studies showing positive benefits of melatonin for sleep have come from the MIT lab of Dr. Richard Wurtman and his colleagues. Dr. Wurtman is a well respected neuromolecular researcher and very successful businessman. Unfortunately, both he and MIT have a significant conflict of interest as they hold a large financial stake in a company that makes melatonin. This is not to imply Dr. Wurtman did not conduct his experiments on melatonin properly (although studies to date have relatively few test subjects). We simply point out that this MIT group has a strong financial stake in the commercial marketing of melatonin and among mainstream researchers has been responsible for a majority of studies finding positive benefit from melatonin. Well done studies with positive findings from other groups not having a financial interest in melatonin are needed.

Dr. Wurtman also held a "use patent" on the now discredited diet drug Redux that was pulled off the market by the FDA because it caused heart injury and death in a small number of patients. A person finding a new use for a medication can apply for a "use patent" even if they did not patent the original medication. This gives them the right to license and collect royalties every time the medication it is sold for the purpose they patented. Dr. Wurtman's affiliates have recently received a "use patent" on Prozac for the treatment of PMS.

(the above information can be found at using the sites own search engine by typing "Wurtman")

Can melatonin be harmful?

While short-term studies indicate that it has very low toxicity, there are no long-term safety data. All of the studies reported here concern healthy adult volunteers and the use of a preparation licensed for human experimental use and available on a named patient basis on prescription. There are no data on uncontrolled preparations available over the counter in some countries, including the United States. Its effects in pregnancy, interaction with other medications, and many other considerations remain to be addressed. Melatonin shouldn't be given to children because so little is known about its effects in children.

The impact and effect of contaminants that are present in dietary supplements were dramatically highlighted by the outbreak of eosinophilia-myalgia syndrome (a very painful disease in which the body's immune system is triggered to attack muscle and other tissues) that occurred in 1989.

The outbreak was triggered by the consumption of contaminated L-tryptophan manufactured by Showa Denko K.K. of Japan and resulted in 38 documented deaths and over 1500 illnesses. It was made using a newly generated bacterium that was very efficient at making a lot of L-tryptophan. However, it also made some brand-new impurities which no one recognized. Subsequently, researchers at the Centers for Disease Control and Prevention demonstrated that at least six contaminants, namely peaks E, C, FF, UV-5 (also known as PAA), 200 and AAA, were case-implicated compounds.

More recently, a group of researchers we have characterized the structure of a number of contaminants present in over-the-counter melatonin products and found them to be almost identical to the case-implicated contaminants that were present in L-tryptophan manufactured by Showa Denko K.K.

This would lead us to believe that over the counter melatonin preparations are being mass produced by genetically engineered bacteria. The use of gene splicing into bacteria is used to make many current medicines including insulin and growth hormone. However, strict oversight and testing required for medication manufacturing is not present in the manufacturing of dietary or herbal supplements.

No cases of disease similar to eosinophilia-myalgia syndrome have been reported, to our knowledge, from patients ingesting melatonin. This may be due to differences in consumption. A typical daily intake of melatonin for jet lag is approximately 5 milligram (mg) per day for an average of seven days. In contrast, the daily intake of L-tryptophan in patients who contracted eosinophilia-myalgia syndrome was approximately 500 mg--15 gram (g) per day over several months (3 g per day for patients using it as a health food supplement and 3 to 15 g per day for patients under medical supervision). For those who are not metrically inclined 1 gram (g) equals 1000 milligrams (mg).

They conclude that the presence of impurities in commercially available melatonin raises serious questions about the possible consequences after long-term consumption, especially when used at doses higher than recommended.

Bottom Line

Melatonin appears to be safe when used as instructed. However, whether or not it helps with sleep is open to debate. There is no solid evidence to support using melatonin supplements to prevent insomnia, jet lag, fight cancer, enhance sexuality or slow the aging process. More study is needed and until research is complete use of melatonin supplements is not recommended.

Melatonin prevents ovulation, so don't use it if you want to become pregnant. Avoid it if you have severe allergies or immune disease, and don't give it to children.



"MELATONIN- Separating the hype from the hormone". Originally published in Mayo Clinic Health Letter, August 1997 at

"DIETARY SUPPLEMENTS-Worrisome contaminants found ". August 1998 at

"Over-the-Counter Melatonin Products and Contamination: To The Editor"- in American Family Physician STEPHEN NAYLOR, PH.D. Director, Biomedical Mass Spectrometry Facility Department of Biochemistry and Molecular Biology Mayo Clinic Rochester, MN 55905 GERALD J. GLEICH, M.D. Department of Immunology and Medicine Mayo Clinic Rochester, MN

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