This story caught my eye just now, concerning a member of the band Supergrass who sleepwalked out of a first floor window and broke his back. Not because I'm especially a fan of Supergrass, but because I almost had a similar accident several years ago. I haven't walked in my sleep for some time, but I have been prone to do so in times of stress - this possibly accounts for my ability to get up and in to the room with a crying child in the night without actually waking properly until I get there. When I was 18, my best friend and I interrailed in Europe and although the experience was exciting and enriching, it was obviously stressful too, because a couple of weeks in, my friend woke me in the night and stopped me from opening the shutters of our youth hostel room. I was dreaming that we were trapped in a cellar and this was the way out: I remember vividly coming back to reality to find myself kneeling on the table under the window leaning against the shutters. My friend and I were very concerned by this, as the shutter catch wasn't very secure and was all that stood between me and a drop to the pavement outside. And we were on the fifth floor.
Needless to say, for the remainder of our stay in that particular room, we tied the shutters closed with string at night for added security. It makes for a good story, but it's a fairly terrifying thing if you consider the possible implications...