Important to understand is that caffeine does not remove sleepiness, instead it offsets the time at which you become sleepy. You "borrow" the energy. You don't create more energy. So after the caffeine effects wear off you are MORE tired than you would be without caffeine, or at least you FEEL more tired.

( ~36:32)

caffeine is an adenosine antagonist which reduces fatigue and lethargy (verbatim copy of Muhammed's annotation)

It will temporarily park receptors for the sleep inducing neurochemical of adenosine. Kind of making those receptors sleep themselves. Which reduces if not eliminated the influence of that chemical for a while.

36:00 caffeine is an adenosine antagonist which reduces fatigue and lethargy

ATP better known as Adenosine triphosphate is an energy carrying molecule found in all living things cells. ATP takes the chemical energy from the process of breaking down food molecules to releases it as fuel for cellular processes.