Clinical ReviewEvidence for the efficacy of melatonin in the treatment of primary adult sleep disorders
Section snippets
Melatonin use in sleep disorders
Clinically significant sleep disorders affect at least 10% of Western populations, and one third or more of the population suffers daily from a sleep disturbance or excessive daytime sleepiness [1]. Management of many of these sleep disorders often requires complex therapeutic regimens, involving both pharmacological and non-pharmacological interventions.
When considering pharmacological management of sleep disorders, drugs which have a short half-life are preferable to minimise ‘hangover’
Biology of melatonin
In humans, the primary physiological function of melatonin is to reinforce darkness-related behaviour, such as sleep propensity [15]. Inadequate sleep can not only lead to a reduction in daytime performance and excessive sleepiness, but chronic inadequate sleep may lead to immunosuppression and increased cancer-stimulatory cytokine production [16].
Endogenous melatonin synthesis is finely regulated by visual light cues received by the hypothalamic suprachiasmatic nucleus in the brain, the site
Method
A meta-analysis was performed including the published, peer-reviewed randomised controlled trials (RTC) on the use of exogenous melatonin to treat primary sleep disorders that we included in this review.
Search strategy
The databases used to search the literature for this review were MEDLINE (1950- present), Embase (1980- present), PsycINFO (1987- present), and Scopus (1990- present). These databases allowed for a wide range of clinical medical material to be covered over a broad base of global journals [35].
Results
A total of 5030 articles were identified in the initial database and hand search (3696 Embase, 790 MEDLINE, 496 PsycINFO, 48 Scopus) of journals. From this, 361 abstracts were assessed and 27 met inclusion criteria. Fifteen articles were then excluded for reasons described below, resulting in a final 12 which were included (Fig. 1). The studies included in analysis comprised a total of 1510 patients, all aged between 18 and 80 y with either primary insomnia, DSPS, blindness, or RBD. Each study
Discussion
This review has shown evidence that melatonin has a role in the treatment of some primary sleep disorders, namely primary insomnia, DSPS, non-24 h sleep-wake disorder and in people who are blind. There is some evidence that melatonin may be beneficial for those with RBD, but more research is required to draw this conclusion. Melatonin facilitates achieving better sleep for these patients by reducing the sleep-onset latency [52] or by regulating sleep-wake times to coincide with the natural
Conflicts of interest
The authors report no conflict of interest in the preparation of this work.
Acknowledgements
Sincere thanks to Lisa Wood and Tomas Ray for assistance with editing.
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