I'm so glad that you're going to look into this. That is the first big step to feeling better. Also, what you said about being contageous isn't entirely false. Living with/being around other people with depression or bi-polar conditions can affect you and your mood.
I have a very dear friend who has pretty severe depression, and while she was living with one girl ,who was also very depressed, and another who was bi-polar, it really had a negative affect on her already depressive condition. The environment was horrible, and none of them even knew about it. Once my friend moved out...she felt so much happier. Wierd, huh?

Another thing you can do to help elevate your mood is St. John's Wort. I have actually been off my medication for some time now (I really need to go back on since I've been really down since the seperation), but I've been taking the St. John's Wort, which actually has been helping.

If you ever need anything, I'm just a PM away.

**hugs**