DAE Have conversations with people while dreaming?

I fall asleep extremely easily when I'm laying in any bed (especially my own). So, when my girlfriend and I lay in her bed at night and start talking, I sometimes fall asleep mid-conversation. When this happens, I continue the conversation as normally as possible, but end up saying things that have nothing to do with what we're talking about. For example, one night she asked me a question about one of our friends and I answered "it's because you haven't had enough potato chips" (this obviously had nothing to do with the conversation). The weird part is that I'm asleep when I say it, so when she wakes me up by asking what the hell it is I'm talking about, I have absolutely no memory of saying it (although if I try hard enough I can vaguely remember the dream itself). This happens all the time, in fact just the other night I said something to her about a pregnant lady. Sometimes she says I actually respond several times before waking up. I don't do any sleep talking other than right when I fall asleep mid-conversation like that. Does anyone else do this?