Good question and if we can work that out it might help us alot. If you take a look at Bob's "Rational Thought" thread, we were discussing how maybe if you just keep analyzing the hell out of an issue, you might find a reason. I think you just have to focus energy on searching for those triggers. Problem is, as you know, we have no idea something affects us the way it does half the time. I don't know if I'm any help because I'm about as confused as they come but I'm really trying to get to the bottom of this illness. I do think that the triggers are often the ones we least expect.
I think when you suffer from depression, even the teletubbies can bring on a bout of sadness or hopelessness if you associate it with something sad. Some days I can listen to certain music and I'm fine but if I'm getting low I can listen to the same song and picture my funeral. Is it us or is it the music? I think we have triggers and if we're going down we are more likely to be affected by a certain song or anything that we associate with something that brings us down whether we realize it or not. I think all people are that way but if you suffer from depression, it's probably worse.
I do know music can make me feel better so I would assume that it can negatively effect one's mood....certainly a song with associations to a lost love for example could trigger a sad feeling leading to sad thoughts leading to depression.Trisha