Your brain is a kindergarten, your executive function is the kindergarten teacher (who had 3 hours sleep and skipped breakfast).
Giving them all a couple of donuts won't make much difference to the kids who are already feral, but it will pep up the teacher and allow them to take charge a bit better.
The way I've always thought about it:
You're listening to music at a party, but there's lots of people around you talking so you keep getting distracted.
Stimulants turn the music up, so the sound of talking disappears.
Stimulants work because what theyre actually stimulating is your prefrontal cortex and the executive function associated with it. The teacher needs coffee analogy in another comment is reasonably spot on.
What about just hydrogen and oxygen
also very flammable
