On May, 23 1987, Kenneth Parks, a twenty-three year old man with a wife and an infant daughter, drove 10 miles to his in-laws house and killed his mother-in-law as well as injuring his father-in-law. In court he was found NOT GUILTY of murder because he was "unaware of his actions" due to sleepwalking. Now this seems ridiculous. How can someone walk out of their house, drive a car 10 miles, and kill someone?
Usually when people sleepwalk, they do not engage in any other actions other than walking. When someone is sleepwalking, it usually looks like they are walking normally (maybe a little more clumsily). So for someone to drive a car and commit murder is something extremely uncommon. But with 6 billion people in the world and with 4 to 5% of adults and up to 30% of children having experienced sleepwalking, there are some cases of "extreme sleepwalking."
One man is able to create beautiful artwork (but only when he's sleepwalking.) One women has sex with strangers in her "sleep". People have sleepwalked out of their bedroom windows. This website has more examples of extreme sleepwalking. http://www.oddee.com/item_96680.aspx
Sleepwalking occurs in the non-REM stages of sleep. Usually in stages 3 and 4 (the deepest stages of sleep.) Sleepwalking is a real thing and occurs naturally. It even occurs with animals. My dog run while he is sleeping, and here is a funny video of a sleepwalking dog.
Whether you believe that a man could really drive a car and kill someone while still being asleep, or believe that there must be other motives, you cannot deny that sleepwalking is a real, psychological phenomenon.