The most recent treatment guidelines on delayed sleep phase disorder recommend the use of melatonin. However, these guidelines are in need of an update. Numerous systematic reviews and meta-analyses have since been conducted. This research aims to summarize all systematic reviews and meta-analyses investigating the efficacy of melatonin in delayed sleep phase disorder.

We performed a literature search using Pubmed, Embase, Cochrane Database of Systematic Reviews and Google. Characteristics and findings of all eligible systematic reviews and meta-analyses were summarised.

Five reviews, which included trials up to 2014, were obtained. The timing of melatonin administration and outcomes of interest varied considerably amongst the trials. All of the reviews found improvement in sleep-onset latency, while two reviews noted advancement in melatonin onset time.

There is a need for more updated evidence exploring the use of melatonin in delayed sleep phase disorder. Future studies should also specify if they are evaluating the hypnotic and/or chronobiotic effects of melatonin and consider these in their design.