This smell is presumably made up mostly of bits of me. Sweat, oil, skin flakes, plus maybe some deodorant and possible a little soap and shampoo. My cat may contribute some but given our relative surface areas i'm probably about an order of magnitude more significant.
All those things together plus time in which they can mix and react and ferment and such equals a smell that doesn't smell like me, or at least not how i smell to myself, but it still seems like a fairly nice smell to me given how familiar it is and given how it's associated with pleasant things like bed and sleep. It makes it nice to curl up in my comforter when i'm going to bed at night.
In spite of its pleasantness however it probably also means my bed is dirty and i should clean it =P