Why sleepwalking?

Hey all? Does anyone know how does sleepwalking work? Are you sleeping and at the same time in real life? Is it possible that one can do something you dont want, like killing a person, while sleepwalking? What if you feel like doing it but normally wouldnt do it? Could you doit while sleepwalking and wakeup remembering nothing?
Has anyone had some strange experiences with sleepwalking?

I moved this from beyond dreaming.
We have had some previous sleep walking topics…
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There have been some murder cases were people pleaded to be sleeping, and I know at least one where it was ruled that they were sleepwalking.

Yeah thats why im asking…thats really creepy. Thanks for the links moogle.