Well, besides staying up for school work... I used to get about 5 hours of sleep on average.
I love staying up late... but I have to get up and go to school. X.X
So, naturally, I love to stay up as long as I can during the summer. Like, right now. It's 2:41 a.m. where I live... and I'm just starting to liven up!
Sadly... I've never stayed up past a 25 hour-ish period with absolutely no sleep. I'm a wuss, I know. :D