Try using an IPOD and listening to Hemi Sync at night before bed, it works great at balancing both sides of the brain and blocks out other distractions:)
I have a brother who always has music playing in his head - it used to drive him crazy. But now he says he's capable of "changing the song" in his brain - LOL. Usually the song that gets stuck in his head is the last song he heard on his ipod. But no, you're not crazy, and this does happen to other people. I never looked it up to see what causes the brain to continually play music like this. But my brother has it 24/7.
That's strange. I have noticed that I , along with millions of other people I am sure, have problems going to sleep when I have something on my mind. Stress or something bad or exciting or anything else that would stay on your mind. If I have something 'on my mind' then I can't sleep I will stay up for hours just lying in bed thinking about it. I have to turn on the TV so that I watch whatever is on and take my mind off of what ever I am thinking about.
It's weird that it's music...unless maybe you are a musician? Are you? If so that may be why you are hung up on music.
I have noticed that when I spend a day on the computer playing say...poker or rummy all day, I will actually have problems going to sleep cause I will sit there seeing hand and playing the game as if I am playing at a table....again, I have to drowned it out with TV.... good luck. I am interested in seeing what others say!