As fate would have it, the longest I have been awake is very close to 48 hrs, mostly on the move with pack, when I was in my late 40s.... was nothing more than a personal challenge to myself.
I had marginally more in me to stay awake, but I am rather sure I could not have gone on to perform anything extra-ordinary with that level of fatigue, - only cause I wasn't Bear Grylls, but admittedly neither was I ultra -fit prepped in the physical/mental sense.
-Bulletproof and Waterproof don't mean Idiotproof.