Caffeine: It’s likely the most widely used mood- and performance-enhancing drug.   However, have you ever noticed that some people are wired all day from one cup of coffee in the morning while others can drink it right before bed? Interested in harnessing the performance-enhancing benefits of caffeine? Mark Goodman, MD, recommends you start by eliminating regular caffeine consumption. Then you can reintroduce a small amount approximately 60 minutes before your workout to observe its effect on your performance.  Experiment with timing and dosage, and keep in mind that some individuals might experience a neutral or even negative effect, so it may take a few trials to find the best formula for you.