For long I have observed such a weird thing: everytime when I had a coffee, in about ten minutes or plus, I feel sleepy. I wonder why coffee makes me sleep, on the opposite to the effect on all the others.
Recently, I have figured it out: it’s my body telling me to take a coffee and at that moment, I don’t feel the need though. Soon after the coffee, before the coffee taking effect, I feel sleepy. Coffee doesn’t make me sleep, which makes sense.