Not everyone can be lulled to sleep with music. Audio is a stimulus and engages the brain as your ears pick up the sounds. How can the brain send the body to sleep when there is a stimulus shouting at it?
Even if you manage to fall asleep with music on, it is such a stimulus that it can creep into your dream.
Music causes magic sleep.
— Mythology Bot (@MythologyBot) October 28, 2018