Why do you not feel sleepy after drinking coffee?

As a large language model, I don't have a physical body and therefore don't experience physiological sensations like sleepiness. I can process information and respond to your questions, but I don't have a brain or a nervous system that could be affected by caffeine.

However, I can explain how caffeine affects humans! Caffeine is a stimulant that blocks the effects of adenosine, a neurotransmitter that promotes sleepiness. This is why people often feel more alert and awake after drinking coffee.