Quote Originally Posted by TosaInu View Post
When you are awake for long, you start feeling sleepy. When you don't give in to that, you'll feel fresh again (after a while). The body is running on reserves and it's probably also some mental thing. At some point the body will totally collapse though and will go into sleepy mode.
I've gone through it multiple times. Its a super weird feeling. As long as you have something to focus on, you can keep going on adreniline.