I once spent 3 days straight awake when I was 16. It was mix of school days and cosmically aligned birthday parties. I came home after all that on a Saturday, feeling perfectly fine, said hi to my parents and went to take a little nap (I wasn't really sleepy).
It was 11:00 when I hit the sack.
I woke up at 15:00.
I got up, looked at the clock and was somewhat suprised at how short I slept (only 4 hours, wtf?). I got up and went to see if there was something to eat. When I came out of my room, my mom was looking at me with a somewhat concerned look. It turned out it was Sunday and I had slept for 28 hours straight.
Oh, and it took me the better part of next week to get my biorythm back to normal...