This week's Please Explain will answer all of our caffeine-related questions, from whether or not we should drink coffee before we run a marathon to how caffeine differs from other stimulants. Bennett Alan Weinberg, co-author of the book The World of Caffeine: The Science and Culture of the World's Most Popular Drug, explains how the world's most popular drug affects us.

Do you have a question about how caffeine affects you? Ask it as a comment!