Ultimately it falls down to sheer determination and of coz the most important rule of all...dont lie on the bed when ur tired (a few mins is okay but not too long, it's when u feel ur whole body starting to loosen up, that means ur close to sleep edi
) coz ur bound to fall asleep. Things like exercising, haha, tat wont reli work if ur studying for instance coz it'll just make u tired and u'll just lose concentration. If staying up just for the fun of it or for no reason at all...then it's pretty easy to stay awake for 2-3 days. It's when u do things like study...then it's hard to stay awake. All the concentration needed reli zaps out the energy in you.