Also known as somnambulism or noctambulism, it is a phenomenon of combined sleep and wakefulness.
It is classified as a sleep disorder belonging to the parasomnia family. It occurs during slow wave stage of sleep, in a state of low consciousness, with performance of activities that are usually done during a state of waking consciousness.
These activities can be as benign as talking, sitting up in bed, walking to a bathroom, eating, and cleaning, or as hazardous as cooking, driving a motor vehicle, and violent gestures.
The typical popular culture depiction may be a zombie pose.