I always wake up with a song already stuck in my head. Why does that happen?
It means you are starting to lose it. See a professional.
I'm guessing you like that song a lot. Do you listen to music before you go to bed?
I do that, too. I read that Keith Richards would often wake up with a guitar riff in his head. I have no idea why.
When songs get stuck in your head you'll most likely keep that song in your head all night
it happens to me if I leave the tv on all night.