I decided to quit coffee about a month ago because even though it is not that harmful to my health I realised I only consumed it because of addiction rather than it making my life any better. Considering I abstain from all other social drugs anyway, and it was also the last big source of sugar in my life, that was also convenient.
The constant headache went by in a week or so, but these last two days have been the first time since that I haven’t had sudden urges to nap in the afternoon. I never expected quitting coffee to be so disruptive for such a mild drug, so I can’t even imagine how much worse it would be with alcohol, opioids or crack or doing it while particularly busy. It also helped me get my sleep in order, which I dumbly didn’t even think about beforehand. Heartly recommend trying it out (in your time off!).
To provide an anecdote of a different experience quitting coffee, I tried it before and went from 36-48 oz of black coffee per day to nothing and had no headaches or improvements sleeping or particular caffeine cravings. The only noticiable Difference for me was that it took me longer to wake up in the morning. Needless to say I went back to drinking coffee after a couple months as I like it quite a bit. I know for others the withdrawal can be quite bad, so YMMV