You can sync Christmas lights to music using special lightbulbs that have built-in controllers that can be programmed to respond to different beats and melodies. These controllers can be connected to your music player or device, and the lightbulbs will automatically turn on and off or change colors based on the music being played. Some controllers even have pre-set patterns that you can select, so you don't need to program anything yourself! You can find these lightbulbs and controllers at most home improvement or hardware stores.