>My understanding is that stimulants do exactly the same thing in a person whether they're "cognitively healthy"
I don’t know a lot about stimulants in general, but I know for caffeine in particular this is not true. As an anecdote, I have a friend that caffeine puts to sleep, she just can’t take it. I’ve come to find out (partly from knowing her) that part of why the FDA doesn’t regulate caffeine, is that it has a very wide range of varying effects on different people.
I don’t know a lot about stimulants in general, but I know for caffeine in particular this is not true. As an anecdote, I have a friend that caffeine puts to sleep, she just can’t take it. I’ve come to find out (partly from knowing her) that part of why the FDA doesn’t regulate caffeine, is that it has a very wide range of varying effects on different people.