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. 2018 Feb 5;16(1):18.
doi: 10.1186/s12916-017-1000-8.

Melatonin and health: an umbrella review of health outcomes and biological mechanisms of action

Pawel P Posadzki  1 , Ram Bajpai  2 , Bhone Myint Kyaw  2 , Nicola J Roberts  3 , Amnon Brzezinski  4 , George I Christopoulos  5 , Ushashree Divakar  2 , Shweta Bajpai  2 , Michael Soljak  2 , Gerard Dunleavy  2 , Krister Jarbrink  2 , Ei Ei Khaing Nang  2 , Chee Kiong Soh  6 , Josip Car  2   7
Affiliations

Melatonin and health: an umbrella review of health outcomes and biological mechanisms of action

Pawel P Posadzki et al. BMC Med. .

Abstract

Background: Our aims were to evaluate critically the evidence from systematic reviews as well as narrative reviews of the effects of melatonin (MLT) on health and to identify the potential mechanisms of action involved.

Methods: An umbrella review of the evidence across systematic reviews and narrative reviews of endogenous and exogenous (supplementation) MLT was undertaken. The Oxman checklist for assessing the methodological quality of the included systematic reviews was utilised. The following databases were searched: MEDLINE, EMBASE, Web of Science, CENTRAL, PsycINFO and CINAHL. In addition, reference lists were screened. We included reviews of the effects of MLT on any type of health-related outcome measure.

Results: Altogether, 195 reviews met the inclusion criteria. Most were of low methodological quality (mean -4.5, standard deviation 6.7). Of those, 164 did not pool the data and were synthesised narratively (qualitatively) whereas the remaining 31 used meta-analytic techniques and were synthesised quantitatively. Seven meta-analyses were significant with P values less than 0.001 under the random-effects model. These pertained to sleep latency, pre-operative anxiety, prevention of agitation and risk of breast cancer.

Conclusions: There is an abundance of reviews evaluating the effects of exogenous and endogenous MLT on health. In general, MLT has been shown to be associated with a wide variety of health outcomes in clinically and methodologically heterogeneous populations. Many reviews stressed the need for more high-quality randomised clinical trials to reduce the existing uncertainties.

Keywords: Effectiveness; Health; Melatonin; Meta-analyses; Systematic reviews; Umbrella review.

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Conflict of interest statement

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Not applicable.

Competing interests

All authors have completed the International Committee of Medical Journal Editors uniform disclosure form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare that they have no competing interests.

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Figures

Fig. 1
Fig. 1
Flow diagram for studies included. MLT melatonin
Fig. 2
Fig. 2
Health conditions with more than ten systematic reviews
Fig. 3
Fig. 3
Distribution of citations of different RCTs in the subset of 31 SRs and MAs included. MA meta-analysis, RCT randomised controlled trial, SR systematic review
See this image and copyright information in PMC

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