moonlightMelatonin is a hormone produced by the pineal gland and associated with regulation of the sleep cycle. There have consequently been melatonin products, and biosynthetic variants (i.e., ramelteon), marketed as sleep aid products. A popular use for melatonin has been to combat jet lag or for adaptation to different time zones. Two recurring questions I have encountered regarding melatonin are whether it actually works and whether there are any adverse side-effects.

The February 10 issue of the British Medical Journal includes a study by a Canadian group that reviewed the efficacy and safety of melatonin use with secondary sleep disorders and sleep restriction. Secondary sleep disorders are sleep problems with a physiologic cause, such as hyperthyroidism or substance abuse (toxicity). Sleep restriction, on the other hand, results from voluntary sleep disruption. On-call physicians or third-shift police officers are examples of people who endure sleep restriction.

According to the meta-analysis (a review of several research efforts examining the same topic) of 15 separate studies (524 participants), melatonin is not effective for both secondary sleep disorders and sleep restriction. Commonly reported side-effects were drowsiness, headache, nausea, and dizziness. Otherwise, the report does not indicate significant adverse effects of short-term melatonin use (3 months or less).

In another meta-analysis performed by the same group, and published two months earlier in the Journal of General Internal Medicine, there is some evidence of efficacy in delayed sleep phase syndrome (DSPS), a shift in the circadian rhythm that makes it difficult for the person to fall asleep and wake up. Study participants who suffered from this disorder were able to fall asleep around 38.8 minutes earlier with melatonin. The study does not however report significant improvement in sleep onset with melatonin use for other sleep disorders. The findings on safety are similar here as in the BMJ article.

In short, melatonin is not effective for most sleep disorders, but it is safe with short-term use.

  • Sources
  • Buscemi N, Vandermeer B, Hooton N, Pandya R, Tjosvold L, Hartling L, Baker G, Klassen TP, Vohra S. The efficacy and safety of exogenous melatonin for primary sleep disorders. A meta-analysis. J Gen Intern Med 2005;20:1151-8.
  • Buscemi N, Vandermeer B, Hooton N, Pandya R, Tjosvold L, Hartling L, Vohra S, Klassen TP, Baker G. Efficacy and safety of exogenous melatonin for secondary sleep disorders and sleep disorders accompanying sleep restriction: meta-analysis. BMJ 2006.

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