tl;dr
How much do you think music reinforces or influences your state of mind? If you're depressed and have a generally negative outlook on life, the universe and everything, is metal and 'new rock'/alternative (let's not even get into emo) going to help keep you there, even if you feel like you're having fun while you listen to it? What about pop music: will it keep you in a lustful or infatuation prone state? Will hip-hop keep you arrogant and quick to anger?
/tl;dr
I would say yes, the music you listen to reflects and reinforces your overall state of mind to a significant degree, particularly if you're like me and listen to music several hours each day.
I was reflecting today on how my musical tastes have changed in the ten years since my teens and early twenties. Most of the music I loved and that really meant something to me back then, if it even gets a spot on my iPod now, gets skipped more often than not when it comes up on shuffle. Some of the stuff I liked back then would be Pearl Jam, NIN, Afghan Whigs, Counting Crows, Catherine Wheel...mostly dark, angsty, depressive and/or angry stuff, which pretty well covers my mindset at the time. Once in a while that stuff will still click with me or I'll give it a nostalgia spin, but my usual response is: nope, too negative--*skip*
These days I tend to get into more complex, more abstract, and more upbeat/celebratory music: jam bands, jazz, 'sparkly' electronic. The outlier would be blues, bluesy folk and strongly blues-influenced rock, which keeps growing on me despite being pretty much the definition of a downer :lol:
Now, I also know that when I am down or surly, the really upbeat stuff in my collection will make me want to to throw up or hit someone :D I'm not saying you can force yourself to be in the mood for something if you're not, but maybe just mixing it up a bit, bringing in a few more upbeat songs or just something abstract and inoffensive can be therapeutic. I'd liken it to the Tone Scale (yes it's from Scientology, but I think it still breaks down mood/energy level pretty well):
Spoiler for Tone Scale:
You're not going to jump ten steps up the scale by listening to a pretty song, but maybe you can ease your way up.
What do you think?