Writers have a very unique problem, because we tend to have two worlds: the world around us and the world inside our heads.
Eh, I think that generalization...is not generalized enough. It's also painters, sculptors, etc artists and probably also engineers and architects and things who are used to creating worlds in their minds. Pop-up bunnies are just as likely to keep one awake at night as pop-up hypothetical structural problems ('s true, a couple techy friends of mine have mentioned it to me.) So at least writers aren't alone in The Crazy!