the United States– caffeine. It’s the addictive and largely unregulated drug found in coffee, energy drinks, tea, cola, chocolate and even pain relievers. Why does caffeine have such a powerful effect on everything from boosting our mood to improving our athletic performance? We’ll visit with journalist Murray Carpenter. He’s written "Caffeinated: How Our Daily Habit Helps, Hurts and Hooks Us." Learn more on Topical Currents. . . Tuesday at 1pm.