I have no idea how it all works, but I think that for many depression sufferers, it's probably a combination of things that makes us depressed. For me, I know that my meds help boost seratonin. I live 8 months of the year in Scotland, and I have to use a special light because lack of sunlight triggers my depression as well. On top of that, I have low self-esteem, social anxiety issues, familial stresses, I'm a university student with an ocean between me and home, AND I have absolutely no idea what I want to do with my life ... and therapy generally helps with those things. In my case, I think that the biological treatments like lights and medication boost my ability to deal with the emotional/psychological issues I have. I'm not sure I could say it's about any one thing.

But believe me, if there was a booster shot that could rid me of my depression completely, I'd be first in line!