u/Comfortable-List-169

I am a student so I often have scenerios where I need to stay up late especially during exam. I have tried different energy drinks when I need to stay up late. Sometimes when I drink I can stay up all night. But sometimes especially with high caffeine ones, I feel drowsy and sleepy within 20-30 mins of drinking it. I can barely keep my eyes open. Even the same drink which made me stay up whole night last day works against me. A normal cup of coffee with sugar have never backfired ever for me. Is this some sort of reaction?