I knew i was dead experience - Your Thoughts

Hey guys,
Can anyone explain this experience.

I went to bed late in the night say about 1:30am , fell asleep my girlfriend came home but didn't have her keys so she knocked on the window.
Instantly upon waking up or so i thought upon hearing the knock i looked at the alarm clock (which i cannot remember if it was the same color when i looked at it red or green).
I instantly felt sick because in my mind i didn't think i was dead i knew i was dead i then screamed (mind you all this is happening in a split second).
My gf then said it was her 3 or so times and told me to open the door.

I opened the door and she said i was as white as a ghost and had tears in my eyes, but nothing like that has ever happened.
I couldn't sleep with the light off for like a week.

I got told from one guy who has OBE's it could me sleep terror.
Anyone got any ideas at all ?

If you don't remember what you were dreaming it could indeed be night terrors. It could be a lot of other things too- how old are you? PS. -I'm moving this to the dreaming forum because this is more related to dreaming, but could be a PSD case too- but we'll deal with that if it is determined it to be so.

How did you come to the conclusion that you were dead?

kiwibonga - i didnt come to the conclusion it was the 1st thing that was in my head it was very weird