I think this monthly withdrawal syndrome with the anhedonia reflects a true gap in scientific understanding of caffeine. There are communities where people routinely quit caffeine (e.g. /r/decaf) who all notice the same thing. Yet if you look at how long caffeine withdrawal lasts: the reference answer is 1 - 2 weeks (then everything is "normal.")

I think caffeine is legitimately more disruptive and addictive than is commonly acknowledged. It creates quite a life-style loop where you need it for [drive, energy, mood, alertness] as a fix to many of the issues it causes, lol. Caffeine is such a widely used drug yet doesn't seem to have been studied that much. It's fascinating to me how the drugs that are socially acceptable seem completely arbitrary. Like alcohol (which in terms of addictiveness isn't far behind the most addictive drugs.)

In tables that compare the most addictive drugs, you know what drug is always missing yet seems to be consumed more widely than any other recreational drug on the planet: caffeine. This is funny though. It may be difficult to actually do high quality, comparative research on caffeine because to do so you would need to find people who don't already consume caffeine and I suspect that is a harder problem than it sounds.

By the way: the set of people who have never been effected by caffeine shrinks even further if you consider whether the mother consumed it during pregnancy.