I have persistent dreams in which I decide to change my career to something more interesting, but requiring a different university degree that the one I have now (CS). In these dreams, I decide to go back to high school to improve on my final grades, so that I have higher chance of getting into my new university of choice (HS grades are a large component of that in Poland). Through these dreams, I attend the HS classes (as a 40-year old), sweat about the homework and exams etc. It's not a nightmare, it's just bizzare.