Sleepwalking occurs during slow wave sleep stage and is the combination of sleep and wakefulness, in chronic cases, it can result to assault or the death of someone else. Sleepwalking is the simple typical behavior of a person, sometimes it can convert to the big accident causing injury to sleepwalker person.
There is no physiological forewarning that indicates a sleepwalking episode is about to occur. There may be a genetic component to sleepwalking. Sleepwalking also disturbs the marital lives of the person. The cause of sleepwalking is not known and no medical treatment can be given to sleepwalker yet.
All people walking in sleep are not always chronic sleepwalkers but they can do really weird things like sit up in bed and talk, shout without getting up, change dress, in illusion about time, go to the kitchen and eat, looking for things under the pillow or under the bed etc. And it is not that easy to wake up a sleepwalker but you can try softly by repeatedly telling to go to bed.
Sleep Scientists call this behavior as sleep inertia and this may continue for 30 minutes. If you wake up such person then he may be confused, angry or scared and react unpredictably. Most sleepwalkers don't remember what they have done during sleepwalking episodes.