Sleep Med Rev. 2005 Feb;9(1):41-50.
Effects of exogenous melatonin on sleep: a meta-analysis.
Brzezinski A,
Vangel MG, Wurtman RJ, Norrie G, Zhdanova I, Ben-Shushan A, Ford
I.
Department of Obstetrics and Gynecology, Hadassah Medical Center, Jerusalem,
Israel. amnonb@cc.huji.ac.il
Exogenous melatonin reportedly induces drowsiness and sleep, and may ameliorate
sleep disturbances, including the nocturnal awakenings associated with old age.
However, existing studies on the soporific efficacy of melatonin have been
highly heterogeneous in regard to inclusion and exclusion criteria, measures to
evaluate insomnia, doses of the medication, and routes of administration. We
reviewed and analyzed (by meta-analysis) available information on effects of
exogenous melatonin on sleep. A MEDLINE search (1980 to December 2003) provided
English-language articles, supplemented by personal files maintained by the
authors. The analysis used information derived from 17 different studies
(involving 284 subjects) that satisfied inclusion criteria. Sleep onset latency,
total sleep duration, and sleep
efficiency were selected as the outcome
measures. The study effect size was taken to be the difference between the
response on placebo and the mean response on melatonin for each outcome
measured. Melatonin treatment significantly reduced sleep onset latency by 4.0
min (95% CI 2.5, 5.4);
increased sleep efficiency by 2.2% (95% CI 0.2, 4.2), and
increased total sleep duration by 12.8 min (95% CI 2.9, 22.8). Since 15 of the
17 studies enrolled healthy subjects or people with no relevant medical
condition other than insomnia, the analysis was also done including only these
15 studies. The sleep onset results were changed to 3.9 min (95% CI (2.5, 5.4));
sleep efficiency increased to 3.1% (95% CI (0.7, 5.5)); sleep duration increased
to 13.7 min (95% CI (3.1, 24.3)).