mel·​a·​to·​nin | \ ˌme-lə-ˈtō-nən How to pronounce melatonin (audio) \

Definition of melatonin

: a vertebrate hormone that is derived from serotonin, is secreted by the pineal gland especially in response to darkness, and has been linked to the regulation of circadian rhythms

Examples of melatonin in a Sentence

Recent Examples on the Web

Taking melatonin can pull the sleep cycle backward. Caroline Picard, Good Housekeeping, "What You Need to Know About OTC Sleep Aids, According to Neurologists," 30 Jan. 2019 Winters recommended 3 to 5 milligrams of melatonin, an over-the-counter supplement that triggers sleep. Chris Erskinecolumnist, Los Angeles Times, "Jet-lagged from that long summer flight? Tips on reducing the fog and fatigue," 16 Aug. 2019 Artificial light can suppresses the production of melatonin, the hormone that regulates sleep, and disrupt the circadian rhythms that dictate sleep patterns. Christopher Ingraham, Washington Post, "Where the last pristine skies in America are," 6 Aug. 2019 In the dark, our body temperature drops, metabolism slows, and the hormone melatonin rises to help induce sleep. Lauren Lee, CNN, "These interior design tips can help you create a bedroom blueprint for better sleep," 6 Aug. 2019 In humans, blue light triggers a cascade of health effects—including disrupting sleep—by interrupting normal cycling of the hormone melatonin. Jenny Howard, National Geographic, "These fish eggs aren't hatching. The culprit? Light pollution.," 9 July 2019 Tart cherry juice mixed with chia seeds Tart cherry juice, a natural source of melatonin, has been shown in several studies to improve sleep. Cynthia Sass, Mph,, "7 Healthy Late-Night Snacks," 3 July 2019 Along with a regimen of melatonin and an essential dose of cannabis indica (Granddaddy Purple and Blackberry Kush helps the sleep train pull into the station more quickly). Times Staff, Los Angeles Times, "The best music to help you fall asleep," 26 July 2019 The addition of a few tablespoons of chia seeds provides not only fiber and plant protein but tryptophan, a precursor to melatonin. Cynthia Sass, Mph,, "7 Healthy Late-Night Snacks," 3 July 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'melatonin.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of melatonin

1958, in the meaning defined above

History and Etymology for melatonin

mela-, extracted from Greek melan-, mélās "black, dark" + -tonin (in serotonin); so named because the hormone can lighten skin color in animals by reversing the effect of melanocyte-stimulating hormones — more at melano-

Note: The word was probably introduced in the first published description of the hormone's isolation: Aaron B. Lerner, et al., "Isolation of melatonin, the pineal gland factor that lightens melanocytes," Journal of the American Chemical Society, vol. 80, no. 10 (May 20, 1958), p. 2587.

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12 Oct 2019

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The first known use of melatonin was in 1958

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mel·​a·​to·​nin | \ ˌmel-ə-ˈtō-nən How to pronounce melatonin (audio) \

Medical Definition of melatonin

: a vertebrate hormone C13H16N2O2 that is derived from serotonin, is secreted by the pineal gland especially in response to darkness, and has been linked to the regulation of circadian rhythms

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