One teaspoon of pure caffeine powder delivers about the same jolt as 25 cups of coffee. The Center for Science in the Public Interest hide caption

itoggle caption The Center for Science in the Public Interest

Ten milligram tablets of the prescription drug Adderall. The drug is used to treat ADHD and is used by some students to boost their academic performance. Jb Reed/Bloomberg via Getty Images hide caption

itoggle caption Jb Reed/Bloomberg via Getty Images