Hate to say it but I have done this to a friend.
I have sleepwalking incidents and have been told I have arguments with the wall, get dressed, make tea and a sandwich, wander about etc.
One night, when much younger than now, my friend and I went clubbing and then stayed at hers. The following morning asked me what I dreamt about. I couldn't remember, then she told me I had grabbed her suddenly with both hands and shook her awake, said something sinister about we need to get out of here and as she sort of fizzed awake wondering how much danger we were in I just lay down and continued to sleep. I felt really bad about it, it's disconcerting to all parties when things like that happen as you have found.
I don't remember the sleep walking/activities incidents unless I wake up next to a cold cup of tea and a room temperature sandwich while watching the TV. Family, friends and partners have told me when they have witnessed it.
I've been to see a psychoanalyst, psychiatrist, therapy, and counciling because I also have nightmares on an almost nightly basis all my life to the point where I find it hard to go to bed. Nothing has helped but I have not attacked anyone beyond grabbing them which is bad enough.
There are all sorts of reasons why people sleepwalk from stress, being half woken by something, to something as simple as needing to go to the loo in the night, it sometimes runs in families. It's worth checking out with a GP though because there could be a cause that is easily rectified.
It would be helpful if your area has a sleep specialist, ask for a referral anyway as he sleepwalks, I couldn't get to see one but you might have one in your region.