caffeine

Discovered in 1819 by a german chemist, it is a central nervous system stimulant, having the effect of temporarily warding off drowsiness, and increasing alertness.

HOW IT WORKS!!!!!!

Caffeine is absorbed by the stomach in around 45 minutes and has a half life of 3-4 hours in the average adult. This means it takes about 3-4 hours to eliminate half of the amount ingested. Acting as a competitive inhibitor to Adenosine receptors (Adenosine is the stuff that makes us sleepy) it keeps you awake. The problem is that once the caffeine is gone the adenosine is still floating around up there and has accumulated even more over the time that caffeine just bought you, so now you're even MORE SLEEPY... aghhhhhh!!!!! This is just skimming the surface of course, but i thought it was interesting, so i looked it up. lol.