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 in 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 promotion 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 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. Melatonin 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. 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.
However in 2002, a review of nine trials revealed that taking 5 mg of melatonin between 10 pm and midnight at the destination helped travelers fall asleep faster and sleep better.
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 receiving 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.
In 2002, researchers in Turkey presented preliminary results of a trails that suggested melatonin could be useful in protecting peripheral blood cells from the damage caused by radiation therapy treatments given to cancer patients.
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
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.
A researcher reported in 2002 that cherries, especially tart varieties, are very rich in melatonin. He recommended choosing firm, plump, shiny cherries with green stems and avoiding those cherries that have become soft or developed brown spots. They can be frozen whole with stems after rinsing and draining well, then spread in a single layer on a baking sheet and frozen until firm. Cherries can be frozen in plastic freezer bags or containers. Cherry juice also retains the antioxidants and melatonin present in the fruit.
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.
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National Sleep Foundation. 1522 K St. NW, Suite 510, Washington, DC 20005. (202) 785–2300. Fax (202) 347–3472. http://www.sleepfoundation.org.
Ken R. Wells
Teresa G. Odle