Caffeine is the most widely used drug — most of us can't make it through the day without it. But what exactly is caffeine and how does it work? The latest Reactions video from the American Chemical Society breaks it down.

When caffeine enters your body, it is broken down into three "daughter" molecules, with similar chemical structures but different actions in the body.

Read more: http://www.businessinsider.com/caffeine-body-brain-impacts-effects-2014-4#ixzz2zFCfOT00