If you stop using a computer or playing video games before bed, you're more likely to fall into deep sleep better than if you were listening to some music. Music, even ambient drone has peaks and troughs and sounds and instruments and crescendos that all stimulate your brain. I've tried sleeping with things like Soma FM's Drone Zone on low and I got better results not using my computer or playing video games before bed.
I've also heard of people using metronomes as sleep aids. Musicians, particularly drummers, sleep with it running at a certain tempo that they're not particularly adept at so the brain learns it.
I suppose the rhythmic ticking of a particular tempo gives the brain something to focus on and calms it down from the "HOLY **** KILL EVERYTHING HOLD MY BEER I GOT THIS OMG THE SERVER IS FULL OF NOOBS" that you might have just minutes before you decide to go to sleep. Which will keep you up unless you're physically exhausted from monster sessions that we had when we were younger and playing WoW vanilla.
Oh, but if you're determined to listen to music; A Winged Victory For The Sullen. Self titled album. It's magical.