Melatonin

Scientific names: circadin, melatol

Common names: Melatonin also is known as MEL.

Efficacy rating:

●●●...Positive clinical trials

Safety rating:

●...Little exposure or very minor concerns.

What is Melatonin used for?

Overview

Melatonin is one of the hormones of the pineal gland that also is produced by extrapineal tissues. Early animal studies in the mid-1960s revealed its ability to affect sexual function, skin color, and other mammalian functions. It also has been implicated in time-keeping mechanisms in the pineal gland. Continual darkness depresses the estrous cycle. Melatonin secretion is inhibited by environmental light and stimulated by darkness, with secretion starting at 9 pm and peaking between 2 and 4 am. Nocturnal secretion of melatonin is highest in children and decreases with age. Studies in the 1990s have widely expanded the use of melatonin for 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.

Although melatonin is not approved for marketing as a drug product, it has been classified as an orphan drug since November 1993 for the treatment of circadian rhythm sleep disorders in blind people with no light perception. It is commercially available as a nutritional supplement either as a synthetic product or derived from animal pineal tissue. Use of the tissue-derived product should be discouraged because of a risk of contamination or viral transmission.

Sleep disorders

Melatonin is used for many conditions, but is showing the most promise in short-term regulation of sleep patterns, including jet lag. There are numerous clinical studies exploiting the role that melatonin plays as a hormone in the body. Major promise currently is seen in short-term treatment of insomnia at low-dose schedules (a few milligrams) nightly.

Other uses

Other possible uses include as an antioxidant, improving the effectiveness of the immune system, and possibly preventing cancer. Many of the more recent studies show some promise in these areas. However, large-scale, double-blind studies are needed because of concern for potentially adverse long-term effects.

What is the dosage of Melatonin?

Jet lag Eastbound travel

Take a preflight early evening treatment of melatonin followed by treatment at bedtime for 4 days after arrival.

Westbound travel

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

Difficulty falling asleep

Take melatonin 5 mg 3 to 4 hours before an imposed sleep period during a 4-week period.

Difficulty maintaining sleep

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

Children (6 months to 14 years of age with sleep disorders)

Melatonin 2 to 5 mg has been used.

Is Melatonin safe?

Contraindications

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

Pregnancy/nursing

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

Interactions

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

Side Effects

Possible adverse effects include headache and depression. Melatonin should not be used by patients who have autoimmune diseases. Drowsiness may be experienced within 30 minutes after taking melatonin and may persist for about one hour, and thus may affect driving skills.

Toxicities

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

References