I learned about these in my psychology class this semester, and I think I experienced one last night.
I went to bed around midnight, and woke up around 12:45, then walked out to my living room. I don't even remember walking out to the living room. After that, my 2 sisters and my parents were in the dining room and saw me in the living room half asleep yelling "HELP ME!" and they were all crowded around me trying to hold onto me and trying to wake me up. My mother threw water in my face, and and I woke up shortly after. I remember as they were trying to wake me up, I could hear and see them, but I couldn't interact with them because I was asleep.
Once I woke up, I couldn't remember what I was dreaming about or what caused this to happen. I then went through like an hour of intense fear, I was afraid of going back into my room, outside and my house. I tried to battle the fear inside my head, and each time I tried revisiting the memory of being half asleep with them trying to wake me up, the intense fear recurred and I started bawling. My heart was racing and my whole body was trembling.
It scared the living crap out of me that every time I tried to remember that moment of being half asleep, this overwhelming intense fear came over me. It was unbelievable. I was absolutely terrified of everything. I took about 2 hours before I was able to calm down and get back to sleep but I still feel so shaken up today. I remembered back to my psych class and I think I experienced a night terror. Wikipedia describes the intense fear as trying to visualize something mentally that's impossible to visualize, which for me was the moment I was half asleep.
Has anyone else had things happen like this? This is some scary shit, and it's amazing how your mind can completely fuck with you. I kept trying to out-smart the fear, but it's just so engulfing. I think I woke up and I thought someone was trying to take over my room or something, so I ran out instantly.