Is there an Earworm in your head?

Is there a maddening tune going round in your head?

Most of us from time to time will find a song going through our head that stays there and you can't get rid of it. It is sometimes called an 'earworm'. I have always been curious as to the origin of the earworm and why we have them. I find that I get the same small set of songs popping into my head at random times. So I got to wondering if they really were random.
I am a hypnotist, and I have a deep interest in the unconscious. I believe that the unconscious mind determines conscious behavior. So to me, the origins of the 'earworms' must some from some process in the unconscious that from time to time leaks out into the conscious. My theory is that if you have a word, or a phrase or a song in your head, then that must be associated with some unconscious process going on.

Those repetitive tunes have meaning

So I monitored what songs they were, and what was happening when they appeared. I sometimes get the same song three times a day, but I can also get that song only after months have passed. To me, there is nothing obvious about the actual words used, or the chorus or anything else that would explain why it appears or what made it relevant.
But after thinking about two particular songs, I think I have managed to work out what is going on, for me at least.

One common song I get in my head is the old Simon and Garfunkel classic "Keep the customer satisfied" I used to worry about how some of the lyrics applied to me, such as 'I get slandered, libeled' or 'one step away from the county line', which made no sense at all in my life.

Find the key phrase

But then I realized that the song appears immediately after something unexpected and good happens to me. The key phrase is the first line "Gee but it's great to be back home". It has nothing to do with being back home - I never left. But I think what is happening is that as I am feeling "Gee it's great" in response to some event in my life, that unconscious feeling is triggering the onset of the song, and it continues playing over and over in my head until the feeling passes.
I get the same thing with 'Raindrops keep falling on my head'. The key to the onset of this song is when I thought that I had done something wrong, or things were going badly. But then I realise that it is actually turning out OK. The key phrase here is "Nothing's worrying me". That is exactly how I feel unconsciously, and that is the feeling that the song encapsulates.