Melatonin

Common names: MEL

Efficacy rating:

ÒÒÒ...Positive clinical trials

Safety rating:

What is Melatonin?

Melatonin is one of the hormones produced by the pineal gland in all vertebrates. It is also produced in extrapineal organs, such as the eye, GI tract, bone, skin, lymphocytes, platelets, and thymus. Early animal studies in the mid-1960s revealed its ability to affect sexual function, skin color, and other mammalian functions. In addition to being produced in vertebrates, melatonin is also found in plants, bacteria, unicellular eukaryotes, and invertebrates.

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Melatonin secretion is inhibited by environmental light and stimulated by darkness, with secretion starting at 9 PM and peaking between 2 and 4 AM at approximately 200 pg/mL. The duration of melatonin production varies throughout the year with shorter periods occurring during the summer months and longer periods occurring during the winter months. Nocturnal secretion of melatonin is highest in children and decreases with age. Studies in the 1990s have led to widely expanded uses of melatonin including easing insomnia, combating jet lag, preventing pregnancy (in large doses), protecting cells from free-radical damage, boosting the immune system, preventing cancer, and extending life.

What is Melatonin used for?

Melatonin is used for numerous conditions but has shown the most promise in short-term regulation of sleep patterns, including jet lag. Results from clinical trials are inconsistent.

What is the dosage of Melatonin?

A preflight, early evening treatment of melatonin should be followed by treatment at bedtime for 4 days after arrival.

Melatonin for 4 days at bedtime when in the new time zone.

Melatonin 5 mg 3 to 4 hours before an imposed sleep period over 4 weeks.

A high dose, repeated low doses, or a controlled-release formulation.

Melatonin 2 to 5 mg has been used.

Up to 20 mg orally/IV for 28 to 30 days then 10 mg orally daily for 1 year.

Is Melatonin safe?

Melatonin should not be used by patients who have autoimmune diseases.

Information regarding safety and efficacy in pregnancy and lactation is lacking.

Caffeine and fluvoxamine may increase the effects of melatonin, while melatonin may decrease the antihypertensive effect of nifedipine. Melatonin may possibly potentiate the effects of warfarin.

Possible adverse reactions include depression, dizziness, enuresis, excessive daytime somnolence, headache, and nausea. Drowsiness may be experienced within 30 minutes after taking melatonin and may persist for approximately 1 hour and, thus, may affect driving ability. There may be an increased risk for seizures in children with severe neurological disorders.

There is little or no evidence of any major toxicities with melatonin, even at high doses.

References

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