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.
The cliff-hunters ride sheer-stalkers vertically down the cliff faces to reach the nests of birds and steal their eggs for sport. Sheer-stalkers are vicious agile lizards about the size of large komodo dragons. They must be muzzled and harnessed, but even so there have been some nasty incidents...