Is Melatonin Actually Effective?
Supplements of this naturally existing hormone are frequently used as a sleep aid. Melatonin is commonly available in liquid and pill form, as well as dissolving strips that are placed under the tongue.
- Migraine and cluster headaches
Melatonin is a hormone naturally synthesized in the pineal gland of the brain. It is produced from the amino acid tryptophan. Through a series of steps tryptophan is converted to serotonin and finally to melatonin. This hormone is responsible for helping to regulate the body’s circadian rhythm, sleep patterns, and secretions from the endocrine system.
Melatonin also facilitates hormone production, growth, pain control, balance and sexual maturation. High levels are produced endogenously up to the age of 20. 1
The rate of melatonin production is affected by light and dark (light inhibits secretion, while darkness stimulates it).
Melatonin production can decrease with age and is influenced by day/night cycles. Prolonged exposure to light can significantly inhibit production.
Melatonin is commonly used to improve circadian rhythm and sleep disturbances in blind adults and children. For the treatment of insomnia, melatonin has been found to modestly reduce the time is takes to fall asleep, but may not improve sleep efficiency. Because melatonin has a short half-life (30 to 60
minutes), sustained-release preparations could possibly have a better effect on prolonged sleep.
Melatonin supplementation may have a varying effect on insomnia caused secondarily to other conditions like depression, schizophrenia and Alzheimer’s disease. Similar to the findings discussed above, a 2006 meta-analysis reported that melatonin increased sleep efficiency but had little effect on the time it takes to fall asleep for these types of secondary sleep disorders.2
There is also some research to support that melatonin may help in the treatment of certain types of cancer. Low melatonin levels have been found in patients suffering from cancers of the breast and prostate. Melatonin may also have an antioxidant effect that can reduce some of the toxic effects of chemotherapy.3 For these reasons, melatonin is sometimes included in regimens for cancer treatment.
For insomnia, typical doses range from 0.3 to 5 grams per day, typically taken at bedtime.4 For jet lag, doses of 0.5 to 5 grams are often administered at bedtime upon arrival at destination. Doses range from 3 to 12 milligrams for treatment of cluster headaches and migraines. 5
Side Effects, Safety and Toxicity:
Properly dosed oral administration of melatonin is considered safe when used for up to two months.6 Long-term effects and safety are unclear.
Oral doses of melatonin that range from 0.3 to 5 grams are typically well-tolerated. Common reported side effects of melatonin use include nausea, headache, dizziness, and drowsiness but these findings in one study were not significant compared to placebo. 7
Women who are pregnant or plan on becoming pregnant should avoid using melatonin as high doses can inhibit ovulation and have a contraceptive effect. 8
Conclusions Based on Available Data:
- Apparently effective for reducing the time it takes to fall asleep
- Apparently ineffective for improving sleep efficiency
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1 Pierce A. The American Pharmaceutical Association Practical Guide to Natural Medicines. New York: The Stonesong Press, 1999:19.
2 Buscemi N, Vandermeer B, Hooton N, et al. Efficacy and safety of exogenous melatonin for secondary sleep disorders and sleep disorders accompanying sleep restriction: meta-analysis. BMJ 2006;332:385-93.
3 Sener G, Satiroglu H, Kabasakal L, et al. The protective effect of melatonin on cisplatin nephrotoxicity. Fundam Clin Pharmacol 2000;14:553-60
4 Zhdanova IV, Wurtman RJ, Regan MM, et al. Melatonin treatment for age-related insomnia. J Clin Endocrinol Metab 2001;86:4727-30.
5 Secreto G, Chiechi LM, Amadori A, et al. Soy isoflavones and melatonin for the relief of climacteric symptoms: a multicenter, double-blind, randomized study. Maturitas 2004;47:11-20.
6 Buscemi N, Vandermeer B, Hooton N, et al. The efficacy and safety of exogenous melatonin for primary sleep disorders. A meta-analysis. J Gen Intern Med 2005;20:1151-8.
7 Buscemi N, Vandermeer B, Pandya R, et al. Melatonin for treatment of sleep disorders. Summary, Evidence Report/ Technology Assessment #108. (Prepared by the Univ of Alberta Evidence-based Practice Center, under Contract#290-02-0023.) AHRQ Publ #05-E002-2. Rockville, MD: Agency for Healthcare Research & Quality. November 2004.
8 Briggs, Freeman, Yafee. Update Drugs in Pregnancy and Lactation. Lippincott Williams & Wilkins, 2001.
9 National Institute of Health, Melatonin Fact Sheet: Accessed 5/18/11 @ http://www.nlm.nih.gov/medlineplus/ druginfo/natural/940.html