I have trouble sleeping myself too. There is no particular song or tune that will help me sleep. If I listen to the tune over and over again, I will feel frustrated instead of getting sleepy. For me, I would have any music turned on, and let them play. And eventually, after some time, I will get sleepy and fall asleep. But some songs are just terrible. It would make you think, and the more you listen, the more awake you are.