If human beings were nocturnal, stereotypical monsters would look very different. amirite?

They need the sun to be able to move, like a solar powered toy. As soon as the sun sets, they simply fall limp where they stand until they are exposed to sun which activates them again. Their biggest problem is that they cannot simply go to sleep indoors or in a coffin at night because then they will never get hit with sunlight and remain in stasis forever.
Day vampires kinda suck actually.

Eh. Monsters with very light skin. But not so light it burns.