The effect of melatonin on sleep quality and insomnia in patients with cancer: a systematic review study.

BACKGROUND: Considering the importance of sleep in the treatment success and quality of life in patients with cancer, it is necessary to seek effective solutions to improve their sleep quality. In this regard, a comprehensive review of the effect of melatonin on sleep can be very useful to provide an evidence-based clinical guide. Therefore, the aim of the present systematic review was to investigate effect of melatonin on sleep quality and insomnia in patients with cancer. METHODS: The present systematic review was conducted in 2021. To find evidence related to the study objective, Iranian databases (SID, Magiran) and international databases (Google scholar, Web of Science, ProQuest, Medline via PubMed, Scopus) were searched using specified keywords (Melatonin, Sleep, insomnia, Cancer, Neoplasms, Carcinomas, Tumor, Carcinomatosis, Carcinomatoses, Sarcomas) from the beginning of the establishment of the mentioned databases until 31st December of 2020. After primary and secondary screening, and selection of studies according to inclusion and exclusion criteria, information obtained from studies were extracted in a checklist with items such as author (year), study design, sample size, age, melatonin dose, duration of intervention, results, and conclusion. RESULTS: From 295 articles found, finally six relevant studies entered the review process. The intervention used in the studies included oral melatonin administration. The minimum and maximum dose of melatonin was 3 mg and 20 mg, respectively, which was taken by patients for 10 days and to four months, usually every night before bedtime in studies. The results of the review showed that melatonin had a significant effect on sleep quality and insomnia in four studies. However, two studies showed no significant improvement on sleep quality after the intervention and melatonin administration, although melatonin had significant effect on increasing sleep efficiency in the short term. CONCLUSIONS: The present review study showed that melatonin may be effective in improving sleep quality and insomnia in patients with cancer. It is suggested to carry out further extensive and detailed studies to achieve the most effective and safest method of melatonin administration in terms of dose and duration of use in order to improve sleep quality among patients with cancer.