My version is usually that I'm already at school (this one started for me in high school and the setting never changed) and I idn't do my homework. I'm starting to panic, worrying how I'll get it done in the next five minutes. What really sucked was when I'd wake up and realize, "Thank god, I've still got time to do ... shit, what was I supposed to be doing?"

I think it was just general anxiety that there's something I should have done and didn't.