What you didn't know about the world's most popular stimulant
You’ve almost certainly taken the world’s most commonly used psychoactive drug. In the U.S. alone, 90 percent of adults consume caffeine daily—often as coffee, but increasingly in the form of beverages, pills, snacks, and even pure powder. Global sales of energy drinks nearly doubled from 2008 to 2013. U.S. emergency-room visits linked to energy drinks doubled from 2007 to 2011, too. As consumption continues to surge and new products enter the market, scientists and regulators are racing to better understand how caffeine affects the human body.
This article was originally published in the June 2015 issue of Popular Science, under the title "Caffeine.”