A randomized placebo-controlled trial evaluating the effect of melatonin on sleep quality in patients with mild–moderate dementia

Background Patients with dementia may suffer from poor sleep quality as well as insomnia and sleep–wake cycle alterations. Objectives The main objective of this study was to evaluate the efficacy of melatonin in improving sleep quality. Methods This was a single-center randomized, double-blinded, placebo-controlled study carried out on outpatients with dementia and sleep alterations (according to Diagnostic and Statistical Manual V criteria) from January 2016 to December 2016. Patients aged 65 years or over with a diagnosis of mild–moderate dementia (Clinical Dementia Rating 1–2) were included. Patients were randomized to receive either 5 mg of melatonin or placebo every night for 8 weeks. The primary outcome was sleep quality according to the Pittsburgh Sleep Quality Index (PSQI). Secondary measurements included Mini-Mental State Examination, Neuropsychiatric Inventory (NPI), Geriatric Depression Scale and Katz and Lawton scales for functionality. Results 40 patients were included (21 in the melatonin group and 19 in the placebo group). Nine patients withdrew from the study, and data of 31 patients were analyzed (16 from the melatonin group and 15 in the placebo group). Baseline characteristics of the population were comparable. PSQI scores improved in both groups at every timepoint compared to baseline, but there were no significant differences between groups. At 8 weeks, there was no difference between groups in any of the secondary outcomes except for the sleep sub-item of the NPI, where melatonin group had lower median scores compared to placebo (1, Interquartile Range = 3, vs. 4.4, Interquartile Range = 4.6, p = 0.03). Conclusion Melatonin administered nightly to older persons with dementia was not effective in improving sleep quality. Clinicaltrials.gov Identifier: NCT03066518.