Main Page | See live article | Alphabetical index Melatonin is a hormone produced by the pineal gland, located in the center of the brain. It is a derivative of the amino acid tryptophan. Melatonin helps regulate sleep-wake or circadian rhythms. Normally, production of melatonin by the pineal is stimulated by darkness and inhibited by light. In recent times, melatonin has become available as a drug and a supplement. It appears to have some use against insomnia and jet lag. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.