The fruit of the coffee tree is composed of caffeine and theobromine. Theobromine is used for instant coffee, and caffeine for everything else. If everyone knows the effect of caffeine, then theobromine causes a completely opposite reaction, that is, it tends to sleep.
Therefore, instant coffee, which we are used to pouring boiling water in the morning, is not something that helps get rid of drowsiness, but on the contrary causes her. But here some people may have a placebo effect, so that each organism can react to this coffee in different ways.
There are videos on YouTube that will tell you in detail about the information I have presented)
Because this coffee is instant
Either you have an overdose of caffeine
Caffeine in combination with theobromine affects all people in different ways, the body perceives caffeine as adrenaline and the body chooses which command to execute : stay awake or turn on the defense mechanism
This is my opinion, I could be wrong
Although in my experience I have not yet met people who want to fall asleep after a cup of coffee beans