Why adults still dream about school

I think its because its something they faced, and dealt with, it didn't destroy their life, the way your parents told you it would.

For years after graduating I would have this sense of undirected foreboding every Sunday.

I finally realized it was just a carry over from years of being a real procrastinator when it came to getting my school work done and the gnawing panic I would get knowing I had a lot of work and little time to do it.

It was weird that after recognizing the source that feeling dissipated pretty quickly and I really embraced being free of it all

My big problem with schools (and likely a contributor to my own nightmares) is how they treat themselves as arbiters of what is good and right, above parent's wishes, and especially above the people sitting in the classrooms. High schools should be treating their students as equals to their teachers at the very least. They're adults at this point, but the inhumane regimentation and arbitrary expectations continue. The odd power dynamic boils my blood. It pounded the agency out of me until more than ten years after graduating high school. Students are customers of the school and therefore should hold vastly more power, yet they're treated as cattle. Yes there are amazing teachers who do everything they can, but they're swimming against a strong current.

For me: time for finals and, oops, I didn’t attend a single class and I have no idea what the final will be about.

Maybe this dream is due to the fact that I missed at least half of all my classes because of basketball at the rec center.

Having dipped into the humanities and social sciences (but ultimately graduated with a Math degree), I'd say that the potential difficulties are different rather than absolute.

You often have to do a TON of reading and synthesis in H or SS fields. Mind-boggling reading lists aren't uncommon. If you're lucky the prose is a friendly style. If not... well, you know that feeling of trying to take in a math text quickly? It's not quite that bad, but it's related, lots of unfamiliar phrasing and terminology that you have to work out the connections between and condense semantics from. And then... you may not have well-defined problems. Essay questions/assignments amount to "come up with some thesis and supporting arguments that show familiarity with the material and the ability to generate interesting insight." Do "interesting" and "shows familiarity with the material" sound like uncomfortably subjective assessments? Why yes. Yes they are. Good luck! Also measuring things and experiments are hard. You can be reasonably dull in the natural sciences and still gather a useful amount of empirical observation; in the social sciences or humanities you're going to have to be pretty clever to get good empirical observations at all.

OTOH I would agree that CS and Math often have an additional level of conceptual difficulty, especially the more abstract the corner of the field you're working with, from "you'll definitely need some well-chosen concrete examples as introductory points and probably a bunch of graduated problem sets leading to the eventual brain-twisting revelation" to "you don't understand this, you just get used to it."

I'm considering a grad program that blends the two, so maybe I'll change my mind when I'm done.