Does this happen to you?

I’m 46. This has recently happened to me enough with old music that I even formed a dumbass hypothesis about it. Here goes: I remember reading that our brains kind of clean or sort themselves when we sleep, deciding things to keep or get rid of (yes, I’m way oversimplifying.) So, maybe whatever old song is in my head when I wake up is where my brain stopped sorting and shifted back to wakefulness? Other things I’ve also considered: 1.) My life right now is pretty monotonous and I’m probably depressed, so since I’m not making a lot of “new” material for my brain to sort through at night, it’s going back to more condensed/core memory areas—to paraphrase Mellencamp—before the thrill of living was gone. 2.) The most likely thing is that I actually *did* hear or think of something during the day that triggered that song or jingle to come up from the depths of my consciousness.