My daughter responds to caffeine or sugar by actually calming down. My other children bounce off the walls if given sugar or caffeine. It is all about brain chemistry.
Another clue if you kid may have ADHD is: if we give her Benedryl for allergies she goes nuts my other kids sleep all day.
BINGO!
My brother would go to sleep after drinking coffee. There are clear markers (to this day, he’ll drink coffee to put himself to sleep).