A society in which people believe that the hundreds of stars that dot the sky are the dreams of the sleeping. When the sun goes down, and the people of the world rest, the dreams begin to seed the sky, disappearing in the morning as the populace awakes once more. It could be just a folk tale, or it could be real...
When you sleep, your soul briefly returns to the place where it was created/goes to when it dies, and seeks nourishment. Everybody's soul is created with a little link (or you could say a greater entity calls it back) to that place so that it can return easily, but upon death, the soul returns via that and annihilates the link as if returns.
Also, as an added thingy, you could say the entity supplying the link, or residue of the links themselves, (whichever) is the source of all arcane power.