Sleepwalking

Sleepwalking, also called somnambulism, is a phenomenon that combines sleep and wakefulness, classed as a parasomnia in which the brain shows both wakefulness and deep, slow-wave non-REM sleep in different regions at the same time. Episodes usually happen during the deep non-REM sleep of the first third of the night, when slow-wave sleep is most prominent, and most people who sleepwalk do so once a night or less. What a sleepwalker does can be as simple as sitting up or talking, or as involved as walking to another room, and in rarer and more hazardous cases can include driving a vehicle or making violent gestures. The person typically has little or no memory of the episode afterward, even though their eyes stay open, often looking dim and glazed. A single episode can last anywhere from about thirty seconds to thirty minutes.