You know, vampires sleeping in coffins is a brilliant idea. Ever been inside a coffin? It’s very quiet in there. That might be something I need to start doing since I cannot tolerate noise while sleeping. I sleep very lightly and a mite landing on a gnat’s butt wakes me up.
Since vampires are supposed to have super-sensitive hearing, perhaps they sleep in coffins to avoid the cacophony of the rest of the world rather than to dodge UV rays.