If I'd stay awake that long I'd probably suffer a heart attack. And after that, I probably would find no sleep another 2 days due to having adjusted. And once I'd find sleep, I'd probably never ever get up again. I'd sleep for 4 days, I bet.
However, the human body takes its downtimes. At some point you believe to be awake, but you're not. Or at least half of your brain is asleep. That is when you can't remember your thoughts or actions in the past five minutes. Because there were probably none.
For me, it is often hard to fall asleep, so I didn't expect myself to fall asleep unwanted. But since I once fell asleep on the highway, driving 140km/h on the left lane, I know better and take precautions. I found myself waking up while feeling refreshed, because there was this bright red light in my eyes. The car in front of me was hitting the brakes.