ABSTRACT
Although sleep is popularly conceptualized as a quiet state without movement, a variety of motor phenomena can occur during this time. With the aid of video-polysomnographic electroencephalographic (EEG) and electromyographic (EMG) monitoring, sleep-related movements can be directly observed. Movements can be described based on duration, amplitude, periodicity, and most importantly their predilection to disturb sleep or produce other undesirable consequences. Sleep-related movement disorders (SRMD) constitute a class of movements that are simple and usually stereotyped, and are associated with undesirable effects such as impaired sleep quantity or quality, and/or impairment in daytime functioning. Unlike parasomnias, they are not associated with sleep-related mentation and are not goaldirected. They may occur during the transition between sleep and waking, and vice versa, or during any sleep stages.
