Congratulations on making it through high school! It can be pretty tough in some places so it's good to hear that you had some good experiences during your time there.
I think it's just because they're less inhibited then when they are fully cognitive so some thoughts tend to be explored more then when you're not sleep deprived. Also sleep deprivation can give you the same cognitive impairment as being drunk btw, so your rational mind is definitely going to...