I have exceeded everyones sleep deprivation times by a few days, but I didn’t do it ahem legitamentley…on the other hand I regularley go 36 hours without sleep when I go from a day to a night shift followed by a day off (no way am I sleeping through my day off!). My personal best was wednesday to the following tuesday at Glastonbury festival in 1998, incidentally I didn’t take a dump or take my boots off as well - do I win some sort of prize?
Well, I have a friend who managed I think 3 days straight without sleep working on a project, and then after a one hour nap continued for another 24 hours. It was rather frightening to see… She has quite dark skin normally (she’s of indian descent); by the end of the fourth day her skin was probably paler than mine, and she looked incredibly fragile.
A friend of a friend allegedly did a week without sleep writing her entire dissertation for her final year of undergraduate, and was experiencing severe hallucinations towards the end of this. I don’t know how much this story is exagerated / confused by my memory, but if it’s at all accurate then it is very worrying. Given that this is third hand information it’s not much of a cite, but this isn’t GD. 
Suffice it to say that I trust the friend who told me this.
Myself, I can’t do it. I can typically manage about 36 hours if I have to - with the aid of caffeine and something to keep me busy - at the end of which I collapse and no amount of motivation will keep me going. I can sometimes manage 36 + a short nap + another 12 or so, but generally not.
After about 20 hours of being awake (say, from 7am to 3 am, really not very out-there) I get very very cranky and god help you if you try to prevent me from getting to my bed.
On the other hand, I an often able to be pretty functional on 3 or 4 hours of sleep per night for a considerable period of time. Of course, now that I get to wake up at 9 for class instead of 6, it happens much less frequently.