listening to music while they're sleeping?

I've certainly fallen asleep and woken up while my music was on before... A lot of the times I'd actually wake up more refreshed than usual. I don't know whether or not to attribute it to waking up to the music or that I'm subconsciously listening to it the whole time... or even just coincidence

Tonight I think I'll try sleeping with some music on, I'm going to use a mix of cool jazz, maybe some shoegaze stuff, nothing too fast or harsh... ideas?