It is more common in those who are overweight and with increasing age. A person will apparently wake from the deepest stage of sleep and then do some quite complicated things like walking around or going up and down stairs. Unless woken at the time, the person will remember nothing about it the next day. Such episodes may be preceded by night terrors. In these the individual appears only half awake, is obviously frightened but without the kind of vivid ideas that characterize nightmares.
Night terrors can also occur on their own, without leading to sleep walking.
Sleepwalkers should be guided gently back to bed and should not be woken up. It may be necessary to take precautions to protect the sleepwalker or others from injury locking doors and windows and locking away any sharp objects like tools. People with night terrors on their own often settle down to sleep again without fully waking. Most of us have had frightening dreams or nightmares. They take place usually during the later part of the night when we have our most vivid and memorable dreams.