Many days I wake up and after a few minutes I realize there's a song in my head, often I don't get that one out for the rest of the day. In many cases, that's a song I heard the day before, or I've been singing in the Karaoke bar that night. In some cases, it's a song that I haven't heard for ages (like "Crash! Boom! Bang!" by Roxette some time a few weeks ago), or even one where it takes me some time to figure out what song it is at all (like the one spinning around in my mind today, I still wonder what it is, even though I'm sure I know it).
I'm particularly proud if what sticks that much is a song I've written myself (recently had that with one called "Where I Belong"). After all, if it has qualities to hold on to my (probably subconscious) mind like that, it's likely not that bad a song after all.
Of course that's different from song even coming to me while dreaming - I have written at least one or two songs where major parts of them were there in my last dream before waking up, and I needed to race to write something of them down to not lose them on the way of fully waking up. That's sometimes the tricky part - making sure that an inspiration from a dream makes it over into the waking world.
Interestingly, with those songs in my head, they're usually not there in a dream but manifest themselves only after being fully awake. (Still fascinating to me how our minds work, and how little we know about it on a really scientific level.)
I wonder if I'll find out what song this is that I have wandering around in my head today - I know it's Country Music, multiple voices with female lead, fast and energetic... Well, I hear that part of the song in my mind repeatedly, I just don't remember what the actual song is...
And as long as I don't go and listen to such a song that occupies my thoughts, it usually holds a pretty tight grab on it...
Update: I guess "Wanna Take You Home" by Gloriana is reasonably near to what spooks me today, and that makes sense as I just bought that CD recently.