I couldn't have told you at the time, but I stayed awake for four or five days. At the time I was working two jobs, and dating a girl so I would work from 10 at night to 7 in the morning, drink some caffeine and hang out with this girl for a few hours, then go to my other job around 11 or so and work until 4 or 5 in the afternoon, then come home and smoke some ganja, which would've certainly put me to sleep on the third and fourth days, but I had to go back to work just about when I would be burning out.
This lasted the better part of a week, I really couldn't have told you which day it was, but then the girl I was hanging out with mentioned that I was wearing the same shirt for three days and I realized that I really should get some sleep.
Additional madness occurring in those days includes;
Writing in a different language, cursive like.
Having lucid dreams involving ending WWII by beating the Nazi's in a race to the top of seven hundred stairs.
Smoking ten packs of cigarettes.
Eating a crapton of food, something like 400 dollars worth.
After that I started practicing polyphasic sleeping, which all you insomniacs should look up as it's a magical experience if you can handle the first week.