You are just letting go; in-tune with the music. How your mind interprets that, is down to you etc..
I used to like to 'gonking' to loud music, now you call it 'air guitar'.
I am of the opinion my finding of metal was good for me.
Back in my college years, just after I escaped from abuse, I was in a very bad state. I would listen to a lot of music. But metal was not one of those genres. Actually, there was a lot of classical. My behaviour during those years? Very aggressive and rather nasty. In general, I wasn't very pleasant at all to be around, to be honest. It's a miracle my mate down the road still considers me a friend today. At this much calmer point in my life, I would, in hindsight, not blame him from walking away.
Anyway, back to the topic. It's when someone first introduced me to an incredibly generic and mainstream band that I can barely consider metal, that I think music started proving to have a certain therapeutic effect.
Eventually I got deeper down the hole of metal, and today I listen to almost all of it.
The genre that I particularly like, and really gets me happy, is power metal. Something about its general sound makes genuinely happy. The albums are often a tale of a hero off to slay a dragon. Little corny, but it gets my energy flowing.
I'm very glad that I found power metal, as it makes me happy, which is a state of mind that is, for me, extremely difficult to experience.