Open Question: Why does Coffee make me feel so good?

Hello, I am an Adult and have an odd reaction to coffee, which really am unable to comprehend. Drinking coffee makes me feel so relaxed and sleepy. Actually when I am not sleepy from it depending on amount. I can actually prepare for my Math exam that i need to pass in June. Suddenly I feel like I'm in heaven in an oomph of glory. Suddenly things slow down instead of racing through my head. Like on television actually one things I like about TV is the fast paced motion of people, places and things. I did not want to intentionally use a noun. But to just elaborate exuberantly my train of thought. Generally this state of mind is for few hours i'm in peace. I am though not using coffee as a drug. Don't drink it everyday but when do drink it see above.