There is a “sleep center” in your brain which regulates the sleeping and waking of your body. When this sleep center goes to work, it does two things: it blocks off part of your brain so that it goes to sleep and you no longer have the will to do anything. It also blocks off certain nerves that bring outside messages to your brain, permitting your body to fall asleep.
Usually this sleep center of your brain and your body are connected, but sometimes they become separated. When this happens, the brain sleeps but the body remains awake. People in this situation usually sit up in bed or stand near it. Some actually get out of bed and walk about, but they don’t do much more than walk. A sleep-walker doesn’t remember his stroll when he is awakened.
Sleep-walking is more common in children than in adults!
Sleepwalking can occur in teens as well. I used to walk in my sleep and end up in my older sister’s bedroom, sometimes turning the tv on without knowing it and once laying down next to her thinking it was my own bed. Scared the crap out of her that night, but then she learned I had a habit of getting up and not knowing it. Pulled me aside one time and told me she’d taken me back to bed several time. I was completely unaware of any of it.