AM earworms

It Ain’t Easy - David Bowie

I am still left wondering where some of them come from and why they are just plopped there the minute I open my eyes. Many are easily traceable. They are jingles or real music being used as jingles recently. Or I heard it on the radio a few days ago.
Or someone mentioned something nearby it which led in a chain of thought to it. Occasionally I know I was singing it in my dream. Although, how does that work? The choosing of the soundtrack for my dream. I’d sure like to know that as well. Anyway, when I can only think of that yes, I was talking very generally about different Bowie almost a week ago, but when something then just presents in this way it is just odd.
I get the whole repetitive part, the true worm of the earworm. That’s a function of OCD among other things, but this question of origins, it’s really kicking my ass.

“Well all the people have got their problems that ain't nothing new
With the help of the good lord we can all pull on through
We can all pull on through get there in the end
Sometimes it’ll take you right up and sometimes down again”