A common misconception is that sleepwalking is acting out the physical movements within a dream, but in fact, sleepwalking occurs earlier on in the night when rapid eye movement (REM), or the "dream stage" of sleep, has not yet occurred.
Activities such as eating, bathing, urinating, dressing, driving cars, whistling, dancing, committing murder, and engaging in sexual intercourse have been reported or claimed to have occurred during sleepwalking. Contrary to popular belief, most cases of sleepwalking do not consist of walking around (without the conscious knowledge of the subject). Most cases of somnambulism occur when the person is awakened (something or someone disturbs their SWS); the person may sit up, look around and immediately go back to sleep. But these kinds of incidences are rarely noticed or reported unless recorded in a sleep clinic.
Sleepwalkers engage in their activities with their eyes open so they can navigate their surroundings, not with their eyes closed and their arms outstretched, as often parodied in cartoons and films. The subject's eyes may have a glazed or empty appearance, and if questioned, the subject will be slow to answer and may be unable to respond in an intelligible manner.
Sleepwalking has in rare cases been used as a defense (sometimes successfully) against charges of murder (see Homicidal somnambulism).
Sleepwalking has been found as a theme in many dramatic works. It is a major plot element in the classic silent German Expressionist film Das Kabinett des Dr. Kaligari (English title: The Cabinet of Dr. Caligari). In Shakespeare's Macbeth, Lady Macbeth sleepwalks because of her overwhelming guilt and insanity. Italian composer Vincenzo Bellini's opera La Sonnambula is named after its heroine, a sleepwalker. In Dario Argento's Phenomena (1985), the protagonist, Jennifer Corvino (Jennifer Connelly), witnesses a murder while sleepwalking. In the film adaptation of Silent Hill, the protagonist's daughter suffers from sleepwalking. In the House episode "Role Model", a woman has sex with her ex-husband while sleepwalking and gets pregnant.
Kenneth Parks, a 23-year-old, drove his car 15 miles to his in-laws' house in May 1987. There, he attacked his father-in-law, leaving him unconscious, and stabbed his mother-in-law, killing her. He then went to the police station saying, "I think I have killed some people." He was bloody, and his hand was badly injured. Parks was unable to recount anything about the murder, and he had no motives for committing them. He was unemployed and stressed. He went to sleep that night thinking about how he was going to visit his in-laws the next day with his wife to tell them about his financial and gambling problems. After a year, he was found not guilty of murder or attempted murder. There was an appeal, but his acquittal was upheld. He did not serve time in a mental ward because "noninsane automatism" (i.e., sleepwalking) is not legally viewed as a mental disorder.