[jack_squat]

I would suggest quitting coffee if you are curious about that. Do it on a Thursday and you will probably be fine by Monday. Try it for a couple weeks and evaluate, most likely your productivity will be unaffected. Your boss won't notice.

On the more general question of whether stimulants are necessary for work... my experience is this idea is bizarre and out of line with professional programmers more than a few years out of university (where desperate students take adderall to cram for exams, and thus come into the workforce with that somewhat normalized).

Once a few years out you will have so many employment options that the idea of risking your heart health for a programming job will seem asinine... like biking to school without a helmet.