Sleep disorders are a feature of the disease and can be worsened by medications.[1] Symptoms can manifest as daytime drowsiness (including sudden sleep attacks resembling narcolepsy), disturbances in REM sleep, or insomnia.[31] REM behavior disorder (RBD), in which people act out dreams, sometimes injuring themselves or their bed partner, may begin many years before the development of motor or cognitive features of PD or DLB.[52]