the muscles in my neck sometimes seem to do their own thing and randomly make my head move up for one little second. They make me nod once. It happens mostly when I'm supposed to be relaxed, when I sit in my couch or lay in bed for example. It does not hurt or anything, it's just really annoying.

I've had this happen last year for a few month and I didn't really care about it, but now that it's back I want it to stop. Is there anything I can do and is this anxiety related?