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Melatonin, chemically ''N''-acetyl-5-methoxytryptamine,〔(【引用サイトリンク】 publisher=Sleepdex )〕 is a substance found in animals, plants, fungi and bacteria. In animals it is a hormone that anticipates the daily onset of darkness; however in other organisms it may have different functions. Likewise, the synthesis of melatonin in animals differs from that in other organisms. In animals, melatonin is involved in the entrainment (synchronization) of the circadian rhythms of physiological functions including sleep timing, blood pressure regulation, seasonal reproduction and many others. Many of melatonin's biological effects in animals are produced through activation of melatonin receptors, while others are due to its role as a pervasive and powerful antioxidant, with a particular role in the protection of nuclear and mitochondrial DNA. The hormone can be used as a sleep aid and in the treatment of some sleep disorders. It can be taken orally in liquid form as well as capsules or tablets in immediate- or prolonged-release form. It is also available in a form to be used sublingually, and as transdermal patches. Melatonin is sold over-the-counter in the U.S. and Canada. In other countries it may require a prescription or it may be unavailable. ==Discovery== Melatonin was first discovered in connection to the mechanism by which some amphibians and reptiles change the color of their skin. As early as 1917, Carey Pratt McCord and Floyd P. Allen discovered that feeding extract of the pineal glands of cows lightened tadpole skin by contracting the dark epidermal melanophores. In 1958, dermatology professor Aaron B. Lerner and colleagues at Yale University, in the hope that a substance from the pineal might be useful in treating skin diseases, isolated the hormone from bovine pineal gland extracts and named it ''melatonin''. In the mid-70s Lynch ''et al.'' demonstrated that the production of melatonin exhibits a circadian rhythm in human pineal glands. The discovery that melatonin is an antioxidant was made in 1993. The first patent for its use as a low-dose sleep aid was granted to Richard Wurtman at MIT in 1995. Around the same time, the hormone got a lot of press as a possible treatment for many illnesses. ''The New England Journal of Medicine'' editorialized in 2000: "With these recent careful and precise observations in blind persons, the true potential of melatonin is becoming evident, and the importance of the timing of treatment is becoming clear. " 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「melatonin」の詳細全文を読む スポンサード リンク
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