Melatonin is a hormone produced naturally in the pineal gland at the base of the brain. It is important in regulating sleep, and may play a role in maintaining circadian rhythm, the body's natural time clock. The hypothalamus keeps track of the amount of sunlight that is taken in by the eye. The less sunlight, the more melatonin that is released by the pineal gland, thereby enhancing and regulating sleep. Melatonin can also be taken an over-the-counter supplement mainly sold in health food stores and pharmacies.
A variety of medical uses for melatonin have been reported but its current popularity stems from its use as a sleep aid and to reduce jet lag . However, medical experts caution that melatonin is not a harmless substance without risks. Natural melatonin production decreases with age and the decrease is associated with some sleep disorders , particularly in the elderly.
According to a Gallup Poll survey taken in 1995 for the National Sleep Foundation, about half of all American adults experience either occasional or chronic sleep problems. The use of melatonin supplements became popular in the mid-1990s as a way of treating insomnia. Numerous scientific studies have supported this claim, although there are a few studies that cast doubt on its effectiveness. People reporting the most benefit generally are those with mild and occasional insomnia and trouble falling asleep. It is not generally recommended for use on a regular basis since its long-term consequences are not known.
The second most popular use of melatonin is to ease the effects of jet lag, a physical condition caused by the disturbance of circadian rhythms, usually associate with air travel across several time zones. Whether or not melatonin works to relive jet lag is still up in the air, since various small-scale studies have yielded conflicting results. In one study of airline passengers, melatonin relieved jet lag when taken before, during, or after an eastward flight but was less effective on westbound flights. Another study indicated it was effective only if taken before a flight. A 1999 study by researchers at Columbia University of 257 travelers found melatonin was no more effective than a placebo as a jet lag antidote.
Melatonin has also been touted by some as an anti-aging agent following the results of an experiment in Italy. An Italian researcher reported that in a laboratory experiment, older mice appeared to grow younger and live longer after being on melatonin. However, there have been no studies in humans to support this claim. Animal tests in Spain and China have appeared to show that melatonin can help prevent some cancers, heart disease , and brain degeneration. Further studies on the benefits, long-term effects, and proper dosage are being conducted through the National Institutes on Aging.
In laboratory and animal experiments, melatonin appears to protect cells and boost the immune system. Melatonin supplementation is sometimes part of a holistic treatment regimen for people with HIV or AIDS. There have been no human trials that support this claim.
Melatonin is available over the counter in varying doses of up to 3 mg per tablet. However, a fraction of this is required for insomnia, usually about 0.3 mg or less. Too much melatonin or taking it at the wrong time can interrupt normal circadian patterns. Melatonin is produced at its highest level in the pineal gland during darkness. Since melatonin occurs naturally in some foods, it can be sold as an over the counter dietary supplement. It is only one of two hormones (the other is DHEA) not regulated by the U.S. Food and Drug Administration (FDA). Natural, animal, and bovine melatonin supplements contain actual extracts from pineal glands. Synthetic melatonin is made from non-animal ingredients and is suitable for vegetarians. It is similar in molecular structure to melatonin produced in the body.
The proper dosage is not known, but it appears to differ greatly depending on the individual and extent of the sleep disorder. Persons starting the hormone should begin with a very low dose, 100-300 mcg, which is 0.1-0.3 mg, or less, and gradually increase the dosage if needed. Melatonin is quick-acting and should be taken about 30 minutes prior to bedtime. For jet lag, the general recommendation is 300 mcg just before boarding the flight and 1.5 mg after arrival before going to bed. Melatonin should not be taken during the day.
Women who are on estrogen or estrogen replacement therapy should not take melatonin without consulting their doctor. Since the safety of melatonin use during pregnancy has not been adequately studied, women who are pregnant or breast feeding a child should not take melatonin. Also, women who are trying to get pregnant should avoid using it since some research suggests it may have a contraceptive effect. Studies in animals suggest melatonin can constrict blood vessels, which can raise blood pressure. Therefore, persons with hypertension or cardiovascular problems should consult with their doctor before taking the hormone. It is not recommended for people with lymphoma or leukemia, and should not be used by children.
Few studies have been done on the long-term effects or correct dosing of melatonin. In one study of melatonin, about 10% of patients said they experienced minor side effects such as nightmares, headaches, morning hangover, depression, and impaired sex drive.
Melatonin should not be taken by people using certain antidepressants, such as Prozac (a serotonin inhibitor) or Nardil (a monoamine oxidase inhibitor). Interaction between melatonin and these types of antidepressants can cause a stroke or heart attack . Preliminary symptoms include confusion, sweating, shaking, fever, lack of coordination, elevated blood pressure, diarrhea, and convulsions.
- Circadian rhythm
- The approximately 24-hour period, also known as the body's time clock, which regulates waking and sleeping periods.
- Dehydroepiandrosterone, a hormone produced by the adrenal glands, that is important in making other hormones, especially estrogen and testosterone.
- A hormone that stimulates development of female secondary sex characteristics.
- Abnormally high blood pressure in the arteries.
- A prolonged and usually abnormal inability to obtain adequate sleep.
- Cancer of the lymph nodes.
- Pineal gland
- A gland about the size of a pea at the base of the brain that is part of the endocrine system.
For Your Information
- Cernaj, Ingborg. Boost Your Vitality With Melatonin: Programming Your Internal Clock for Health & Well Being. Sterling Publications, 1998.
- Olcese, James, ed. Melatonin After Four Decades: An Assessment of Its Potential. Plenum Publishing Corp., 2000.
- Rozencwaig, Roman and Walji Hasnain. The Melatonin and Aging Sourcebook. Hohm Press, 1997.
- Sahelian, Ray. Melatonin: Nature's Sleeping Pill. Avery Publishing Group, 1997.
- Watson, Ronald R., ed. Melatonin in the Promotion of Health. CRC Press, 1998.
- Cupp, Melanie Johns. "Melatonin." American Family Physician. (Oct. 1, 1997): 1421-1426.
- Goodwin, Jan. "Live Longer, Live Better." Vegetarian Times. (Oct. 1998): 74-81.
- McBride, Gail. "Melatonin Disrupts Sleep in Smith-Magenis Syndrome." The Lancet. (Nov. 6, 1999): 1618.
- "Melatonin Might Not Be a Jet Lag Antidote." Environmental Nutrition. (Dec. 1999): 7.
- "Nighttime Hormone Helps Starve Cancers." Science News. (Oct. 2, 1999): 221.
- Scheer, James F. "Dream-Weaver: Melatonin." Better Nutrition. (April 1998): 46-48.
- Silberman, Alex. "Forever Young?" Vegetarian Times (Feb. 2000): 66.
- Ternus, Maureen. "DHEA, Pregnenolone Hormone Hype Heats Up; But What Do We Really Know?" Environmental Nutrition (Sept. 1997): 1-2.
- National Sleep Foundation. 1522 K St. NW, Suite 510, Washington, DC 20005. (202) 785-2300. Fax (202) 347-3472. http://www.sleepfoundation.org.
Gale Encyclopedia of Alternative Medicine. Gale Group, 2001.