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How does REM sleep behavior disorder differ from sleepwalking?

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The primary difference between REM sleep behavior disorder (RBD) and sleepwalking lies in the sleep stage during which they occur and the underlying physiological mechanisms involved.1

REM Sleep Behavior Disorder (RBD): This condition occurs during REM sleep, a phase typically characterized by atonia, or temporary paralysis of skeletal muscles, which prevents individuals from acting out their dreams. In RBD, this paralysis mechanism is disturbed, allowing the sleeper to physically act out or speak in response to dream content, such as kicking or yelling. It is often seen in older adults and is considered a potential indicator of underlying neurodegenerative diseases, such as Parkinson disease or dementia.21
Sleepwalking: Also known as somnambulism, this is an NREM sleep parasomnia that occurs during deep sleep, when dreams are generally absent. It involves complex motor actions—such as walking, dressing, or leaving the house—while the individual remains in a state of reduced alertness and is typically unresponsive to external stimuli. It is most common in children and is often associated with genetic factors.234