We conducted systematic reviews and meta-analyses to evaluate the efficacy of
melatonin versus placebo or other
hypnotic agents in improving sleep quality and quantity in patients with
chronic insomnia. A literature search on Ovid-MEDLINE, EMBASE, and the Cochrane Library was performed up to November 2020. Sleep onset latency, total sleep time, sleep efficiency, sleep quality and quality of life were examined as outcomes. We identified 24 randomized controlled trials of
chronic insomnia including four studies of patients with comorbid
insomnia. All studies were compared with placebo. Due to heterogeneity, we conducted subgroup analyses by age group. In non-comorbid
insomnia,
melatonin was only significantly effective in sleep onset latency and total sleep time in children and adolescents. In adults group,
melatonin was not significantly effective in improving sleep onset latency, total sleep time, and sleep efficiency. In comorbid
insomnia,
melatonin significantly improved sleep onset latency in all age groups, but there was only one study in adults group. In conclusion,
melatonin did not appear to be effective in adults but might be effective in children and adolescents with
chronic insomnia for both comorbid
insomnia and non-comorbid
insomnia. Further studies are needed to establish the efficacy and safety of
melatonin by age groups.