Sleep walking, Paranormal?

My son is a sleepwalker, and around once a week, i will turn around to find him standing in the doorway just staring at me. it used to freak me out a bit but now i am used to it. I find when he sleepwalks he does do anything I tell him too, however he does what i tell him to the letter, with no thinking of his own, for example, when he first started sleepwalking, I thought it was related to his bladder, and when he came out i would tell him "go toilet", and he would drop his pants and pee right where he was standing, needless to say i learnt to actually take him to the loo before telling him to go! If i tell him to "go back to bed" he will turn away and go to the first bed he comes across and fall back to sleep. As others have stated he never talks or communicates at all during these walks. I dont think its paranormal. For my son i suspect its related to his stress levels and how tired he is.