Caffeine is a drug that an overwhelming majority of Americans are going about their daily lives under the effect of right now. It alters the brain’s natural state, and stimulates it in a manner similar to cocaine or heroin. Its effects are much milder, of course, but it’s the same mechanism.
-It is absorbed quickly into the lining of the stomach and small intestine.
-It blocks adenosine receptors in your brain. Adenosine causes drowsiness, so cells that would normally be regulated to slow down by way of adenosine actually speed up now.
-Your Pituitary gland sees the cells not slowing down and assumes there is some sort of emergency happening, and it releases hormones into your bloodstream telling your adrenal glands to start pumping.