@rainwarrior i've noticed caffeine does not make me "alert" at all, i've once had 3 red bulls in a night and immediately went to sleep

but i noticed it helped me focus more, especially when i had a clearly defined task at hand (plus the judicious application of loud music in headphones)

i don't have a formal diagnosis of ADHD but treating myself as having it has helped me find coping mechanisms for similar problems you described