I have had hypnogogic images appear while my eyes were open. In fact, a lot of times in the past it's happened before I have even gone to sleep at night. It has stopped now that I'm older, but during my young and teenage years, I used to hallucinate a lot of freaky stuff in the dark, which I'm sure was some kind of night terror or something. It's basically the same as sleep paralysis except with open eyes. In most cases for me, I wasn't even paralysed. One time I remember, I was maybe 17, and I saw a spider in the corner of my room. I sat bolt upright and, still seeing it, I moved away. Then I turned around and it was gone. Another time there was a floating head of a zombie or something. I swatted at it with my hands and it disappeared before my eyes. Bizarre stuff. So you probably weren't asleep, but in a way you were dreaming - just with what you could see with your open eyes as a base for the dream.