I've woken up a few times and found my girlfriend semi-sleep walking, without the walking though. One time she was sat up in the bed cutting imaginary lemons (one job she had to do whilst working at Revolution), and another time she was putting coins into an imaginary vending machine, again whilst sat up in bed!
More recently though she had a full on seizure in her sleep, which the Doctors are now saying was no more than a Night Terror. Didn't feel like it at the time: I woke up to find the bed shaking and weird noises coming from my girlfriend and thought "What the f#ck is that!". It was pitch black so I started fumbling for the switch on my bedside lamp, but before I could get the light on I heard her fall out the bed. Then I eventually get the light on and she's completely the other way around laying on the floor shaking around and slobbering, eyes rolled back etc. I spent a good 5-10 minutes trying to get her to snap out of it, screaming her name, pretty much thinking she was dying at this point as I'd never seen anything like it. I swiftly called an ambulance, followed by my dad (it was 2am) to come watch the baby whilst we were rushed to A&E. Worst experience of my life! Nothing like it has ever happened to her before or since thank god. All she remembers is coming around as I was half way down the stairs with her, some 30 mins after it all began. Pretty grim really, she's only just had the all clear to drive again after several months.
One of the worst sleep experiences I've had was dreaming I was sat having a drink with my mates, when a midget jumps over the table and starts strangling me. So where does this tie in with sleep walking? Well, when I woke up my left hand was gripped around my throat, strangling me, and I had to use all my strength to rip it off with my right hand. I then proceeded to sleep on my left arm for about a month for fear it would happen again!
I also suffer from Sleep paralysis myself, and thats pure hell. I'll let you read up on it, but its basically when your mind wakes up, but your body remains paralysed. Throw in a bit of evil and you've pretty much got it covered. The worst case with that was when I work up paralysed as usual, but was then being infiltrated by the spirit of my mate who'd just died of a brain haemorrage, whilst frantically trying to get myself to snap of it.
I'll finish off my saying though that having watched paranormal activity last night, I'll happily take all of the above over actually walking around the house in my sleep!!