I'm pretty sure that toddlers can sleep walk, and we've seen the beginnings of it in Tyler. I've heard shuffling around in his room at night and gone in to find him completely asleep, torso bent over laying on the bed, feet on the floor walking in place...not climbing as if he's trying to get back in bed, just marching in place. I watched him for a few minutes and he just stopped and stayed asleep, half on the bed, half off. Weird.
For that reason, we keep his bedroom door closed when he sleeps. He doesn't know how to open doors yet, and when he figures it out, we'll probably put a gate up.