Clonazepam has been used for treatment of choice of RBD. However, the efficacy of clonazepam is not proven in the clinical trial. Clonazepam has several side effects that could be problematic in PD patients such as increasing fall-down risk, daytime somnolence, and cognitive decline. Melatonin is a second-line treatment option for RBD, but there has been only one randomized crossover trial that evaluated the efficacy of melatonin on RBD. Finally, there has been no study that evaluate and compare the efficacy and safety of melatonin and clonazepam for treatment of RBD.