Does Coffee Pick You Up?

I should have asked George Nemeth this question. Instead I consulted the New England Journal of Medicine.

Caffeine doesn't really keep you awake by supplying extra energy; rather it fools your body into thinking it isn't tired. How? When your brain is tired and wants to slow down, it releases a chemical called adenosine, wich travels to special cells called receptors, where it goes to work counteracting the chemicals that stimulate your brain. Caffeine mimics adenosine, and thereby plugs up your receptors preventing the adenosine from getting through. The result is that your brain never gets the signal to slow down, and it keeps building up stimulants.

Wonder why your brain isn't getting the message? Now you know the rest of the story...