Interesting!
I can have a very quiet mind and, often, do.
However, it has taken me years of practice.
My husband's mind does not quiet down. His is full of anxiety, worry, tasks which need to be completed, etc. He often relates his mind races.
My "quiet mind" just does not want to sleep. It is so strange. It is wide awake and quiet through the night. Just staring at the walls or ceiling, awaiting elusive sleep.

It's not unpleasant, just... odd.
Oh, yes much like TishBuv, I will sometimes start singing verses to a song, verses which relate to something in the Present moment. My poor husband hears the verses and they play and play in his head for a week.
He has a more "obsessive mind" than do I.

WC