What is the role of melatonin in the treatment of insomnia?

Updated: Sep 11, 2018
  • Author: Jasvinder Chawla, MD, MBA; Chief Editor: Selim R Benbadis, MD  more...
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Melatonin has also become a popular OTC sleep aid. Melatonin is a naturally occurring hormone secreted by the pineal gland. The concentration of melatonin is highest in the blood during normal times of sleep and lowest during normal times of wakefulness. The general consensus is that melatonin given during normal waking hours has hypnotic properties.

However, the timing of evening administration is critical as to whether a hypnotic or chronobiologic effect occurs. Melatonin given early in the evening appears to increase sleep time; however, administration 30 minutes before a normal bedtime has not resulted in a decreased sleep latency or an increase in sleep time.

Most studies of melatonin have been small and of limited duration, and the results have conflicted somewhat, with several studies showing limited or no effect. [18] Most of the data, however, seem to suggest that melatonin taken before bedtime decreases sleep latency, may increase total sleep time, [92, 93] and may entrain irregular circadian rhythms.

Studies of melatonin in individuals with chronic insomnia have not demonstrated objective changes in patient sleep habits or changes in mood or alertness the day after treatment. In addition, a dose-response relationship has not been determined. OTC melatonin is also sold at doses much higher than those that naturally occur in the blood. The 2008 AASM guideline notes a relative lack of safety data and efficacy data and, therefore, states that melatonin is not recommended for the treatment of chronic insomnia. [1]

Some studies, however, suggest a possible role for melatonin in the elderly. In a 2010 study, Wade et al determined that prolonged-release melatonin (2 mg) improved sleep latency and additional sleep and daytime parameters in patients 65 years of age and older. These improvements were maintained or enhanced over a 6-month period, with no signs of tolerance. [94]

A double-blind, placebo-controlled clinical trial by Rondanelli et al in residents of a long-term care facility found that a nighttime dose of melatonin, combined with magnesium and zinc, appeared to improve residents’ quality of sleep and quality of life. The supplement, containing 5 mg melatonin, 225 mg magnesium, and 11.25 mg zinc, was administered 1 hour before bedtime. [95]

Melatonin is not recommended by the AASM for sleep onset or sleep maintenance insomnia. [6]

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