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El Cajon, CA
A 31-year-old female asked:

If melatonin's half-life is only 35-50 minutes, why do many sources say to take the supplement 1 to 2 hours before bedtime?

1 doctor answer2 doctors weighed in
Dr. Ralph Morgan Lewis
Family Medicine 39 years experience
See below: Half-life is not the same as onset of action. Melatonin may take 1-2 hours for activity to begin. Half-life determines how long drug stays in system, more specifically how long it takes before 1/2 of drug remains; after 6-7 half-lives lnly 1% of drug remains.

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