I don’t know when or why it started - my thoughts’ll start drifting toward unfortunate memories and I suddenly find myself doing this thing sort of somewhere between humming and scat singing. And it’s always made up - I don’t hum real songs (presumably because that wouldn’t be enough to distract me).

It’s to the point that the two things are sort of reversed in my mind, so instead of recognizing an uncomfortable memory then catching myself humming, I catch myself humming so realize I just remembered something uncomfortable.