Herbs & Supplements

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Uses

In the United States, supplemental melatonin is taken mostly for the short-term relief of sleep disturbances--especially jet lag. Results from several controlled studies show that melatonin taken before, during, and after long-distance travel may lessen or prevent sleep disruption. In addition, melatonin may be associated with less daytime drowsiness than prescription sleeping pills. For individuals who have delayed sleep phase syndrome, which keeps them awake long into the night and delays their wake-up times, taking melatonin may help to establish a more conventional sleep-wake cycle. A recent analysis of several studies, however, found that taking melatonin did not improve sleeping significantly for individuals with jet lag or shift changes. It also failed to show a clinically relevant effect on sleep problems due to physical or mental illnesses. Why some individuals with sleep disorders seem to respond to melatonin supplementation while others apparently do not remains to be proved.

Although it is not approved in the United States as a regular prescription drug, melatonin does have a special orphan drug designation from the U.S. Food and Drug Administration (FDA). An orphan drug has extremely limited uses, such as for the treatment of a rare disease. Melatonin is prescribed as an orphan drug for blind individuals who suffer from sleep disturbances because their daily rhythm is distorted by the lack of light-and-dark effects that help to regulate sleeping cycles in sighted individuals. Melatonin is also available as a dietary supplement without a prescription.

For about 15 years, melatonin supplementation has been studied extensively--mainly in Europe--for treating cancer. In studies conducted in laboratory animals or human cancer cell cultures, melatonin appeared to keep some types of tumors from spreading as rapidly as untreated tumors. Several studies have also been conducted in humans with advanced tumors. In general, supplemental melatonin appeared to help prevent or delay the spread of tumors for many of these individuals, theoretically by keeping cancer cells from absorbing and using an essential fatty acid that is necessary to cancer cell survival and growth. Much more study is needed to confirm this finding. In animal studies, certain cancers, such as leukemia, may have been worsened by supplemental melatonin. For the treatment of cancer, melatonin is most often injected into muscle tissue, but injectable melatonin is not available for use in the United States.

Other current research indicates that melatonin is concentrated in specific cells (which also produce large amounts of natural melatonin) in the stomach and intestines. Among other effects, this gastrointestinal (GI) melatonin blocks the production of stomach acid. GI melatonin also increases blood circulation through the small blood vessels in the lining of the stomach, the intestines, and the pancreas. It may have an immune-boosting effect on tissues in the GI tract, as well. Decreased stomach acid, increased blood flow, and enhanced immune function may all help to heal ulcers and prevent damage caused when non-steroidal anti-inflammatory drugs are taken on a long-term basis. Additionally, the antioxidant effects of melatonin may help to relieve inflammatory bowel diseases.

While clinical research continues for the use of melatonin in many other conditions, no definitive results prove that melatonin is effective for any of them. Examples of ongoing study include:

In recent studies, melatonin has shown some value for easing withdrawal symptoms for individuals who have become dependent on benzodiazepine drugs. Benzodiazepines are often used for relieving insomnia or anxiety, but long-term use may result in dependence.

Other studies show that melatonin supplements may also be useful in helping individuals who are trying to stop smoking.

Melatonin supplements have also shown some effectiveness in lowering blood pressure levels in several human studies and reducing blood cholesterol levels in limited animal studies.

Taking melatonin may increase appetite and lead to weight gain for individuals who lose muscle tissue because they have serious chronic illnesses such as AIDS.

In another study, supplemental melatonin may have prevented cluster headaches in individuals susceptible to having that type of headache.

Because very high oral doses of melatonin are believed to decrease fertility for women, some inconclusive research has been done into its use as a contraceptive.

In other studies, a liquid form of melatonin was applied to the skin to protect from ultraviolet light and sunburn. Injected melatonin has helped to reduce the damage from burns on the skin of laboratory animals.

Very early studies in laboratory animals suggest that melatonin may help to prevent or delay the development of Type 1 diabetes and Alzheimer's disease.