maybe in the mornings, the vampires turn into old people? the age they're supposed to be in? but then, if that's the case probably much older vampires died or turned to dust or very mummy-like. xD
maybe that's the vampire's quirk in this story. xD hahaha!!! weird quirks kinda like the ones from Twilight xD hahahaha!!! but instead of glittering under the sun, they get older.