I've used light therapy too. I really want one of those go-lites, because maybe I would actually use the thing if I can do it anywhere and don't have to have a large area of a desk or table available. It does help when I do it consistently, especially with my sleep/wake cycle, which tends to be way off, but I think it helps with mood too. It's hard to say what is doing what, as I also use St. John's Wort, and if I have my act together I would be exercising outdoors while the sun is up. But I sabotage myself by skipping all of that stuff.

My T that I was going to when we realized that I had SAD told me that just getting outside and also exercising should be enough and I didn't need to invest in the light box. But in the winter when I need that the most, I don't have the motivation to get outside, and I hate being cold. I know someone who just gets a full-spectrum light bulb and installs it in the floor lamp. He says that works and the light bulb is only $10.

Here's a website about bright light therapy: http://www.brightenyourlife.info/pdf/brighten.pdf I like that this author explains how we just don't get enough light in modern society, and everybody needs more light, and he advocates light for treating any kind of depression, not just SAD.