I think the effect varies from person to person. Drink it 15 minutes before the exam, and feel that you can maintain your thinking ability 1 hour. But my friend said it's best to take the math test half an hour in advance. Well, I mainly feel that I must concentrate on the problems I can't do. pass, Red Bull is only used as an aid, and I think the effect is quite good. And chocolate and bananas. Eating bananas before the exam is worse than eating red bull. My sister is a pharmacist. She says that if you think too much, you should eat bananas. . . . . . I always eat bananas and red bull before exams.