Nah, I've done it, 3 full days without sleep. The last day I felt I was going to become insane because I couldn't focus on anything, the real world was getting distorted as it was getting mixed with crazy thoughts that I think were dreams I was having while actually being awake. Scary but interesting.
I go for 2 days without sleep sometimes, specially when I have a trip with my friends to somewhere fairly far. Mostly because we spend the night before drinking and leave in the morning.
When I go for long periods of time without sleeping and then try to sleep it can go in 2 different ways but it's always the same. Either I go to sleep and fall like a brick and don't wake up till 12-16 hours later, or I have problems sleeping with sleep paralysis, nightmares, etc.