It's true that almost every day of the week I wake up with a song in my head... inexplicably there with no reason, not just some afterthought from the night before.
A few months ago I woke up with "Love Will Find a Way" by Yes....and it lasted for like a week. It was almost freaking audible! I started playing it every day to and from work, and eventually I went downstairs to my own little home music studio (been playing keys since the mid 80's) and taught myself the song (mostly) and.tried recording it.
Recently I woke up with some Doors song in my head.(don't remember what it was). Sometimes it's even something somewhat usual, even songs I don't like that much!.