Back in my younger days and to this day I might sometimes take a nap in the late afternoon/early evening and wake up around 6, and if the lighting was just so, I'd freak out and think it was morning and I had to get ready for school/work.
A couple times when I've had the flu I would try to take a nap and just have completely bizarre dreams in the process and wake up feeling like utter crap, like days had passed yet I had not really been able to fall asleep.
As far as New Year's Eve, I'm always at a friend's apartment for that, and though we drink heavily through the night, we've always managed to be awake for midnight. I did once, to my internal embarrassment, fall asleep slightly after while we were trying to pull a Star Wars marathon before and after midnight. Everyone else was already out, but I swore I'd manage to make it through.