The World's Favorite Drug

More than 9 in 10 adults use caffeine every day. It hides in coffee, tea, chocolate, energy drinks, and even painkillers. Here is the part most people get wrong: caffeine does not add energy to your body.

Think of adenosine as a rising tide and caffeine as a sandbag wall around the receptors that sense it. The wall holds the signal back, so you feel alert — but the tide keeps rising behind it. Adenosine does not stop building; caffeine just keeps much of it from landing on its usual receptors for a while.