Myth: Vampires Sleep in Coffins
True Blood: Bill sleeps in a coffin under his house.
Twilight: Vampires don't sleep at all in Stephenie Meyer's world. They don't even need beds, really, unless it's for, um, other stuff.
The Vampire Diaries: While they don't sleep in coffins, the vampires in Mystic Falls do seem to like a bit of shut-eye.