melatonin
noun
mel·a·to·nin
ˌme-lə-ˈtō-nən 
: 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
Humans, specifically, need tryptophan to produce serotonin and melatonin, which respectively regulate mood and sleep.
—
Adriana Pérez, Chicago Tribune, 23 May 2025
Other micronutrients also help support your body’s response to tryptophan and melatonin.
—Madeline Holcombe, CNN Money, 23 May 2025
That includes serotonin, melatonin and micronutrients like magnesium, vitamin B6 and folate, which also help the body to produce melatonin.
—Malaka Gharib, NPR, 19 May 2025
Your body uses tryptophan to synthesize several important molecules, including melatonin and serotonin.
—Merve Ceylan, Health, 12 May 2025
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Adriana Pérez, Chicago Tribune, 23 May 2025
Other micronutrients also help support your body’s response to tryptophan and melatonin.
—Madeline Holcombe, CNN Money, 23 May 2025
That includes serotonin, melatonin and micronutrients like magnesium, vitamin B6 and folate, which also help the body to produce melatonin.
—Malaka Gharib, NPR, 19 May 2025
Your body uses tryptophan to synthesize several important molecules, including melatonin and serotonin.
—Merve Ceylan, Health, 12 May 2025
See All Example Sentences for melatonin
Cite this Entry
“Melatonin.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/melatonin. Accessed 1 Jun. 2025.
Copy CitationKids Definition
melatonin
noun
mel·a·to·nin
ˌmel-ə-ˈtō-nən
: a hormone that is secreted by the pineal gland especially in response to darkness and has been linked to the regulation of bodily functions or activities (as sleep) that occur in approximately 24 hour cycles
Medical Definition
melatonin
noun
mel·a·to·nin
ˌmel-ə-ˈtō-nən
: 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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