What causes people to sleep walk?

Why do people sleep walk? Is it part of a disorder?

• I caught myself sleepwalking last night. I got up from bed with my comforter wrapped around me and tried to walk to my closet because I thought someone was stealing it (crazy I know) I tripped and fell hard to the ground which woke me up. Then I checked to make sure no one was really stealing my closet and then realized how crazy that was and that it was all a dream. So why do people sleep walk? Is it part of a disorder? And if so, what disorder is that? Could I be developing it or does everyone sleep walk every now and then?

• Answer:

  when you sleep, your body paralyzes itself so you don't act out your dreams. sometimes (i think it happens in REM) the body doesn't quite accomplish that. this results in sleep walking and/or sleep paralysis. sleep paralysis is ridiculously more scary than sleep walking. less dangerous though...