I struggle in the winter time with low mood as well, but this year I started using a SAD lamp and it has made a difference for me. I use it in the morning when I wake up or if I don't have time to use it before work I come home and use it at lunch. I found I had to start with short amounts of use because it gave me a headache. (This is common if a person has fair skin/fair eyes) I now use it for 30 minutes a day.
I have the travelite and I purchased it from this company:
http://www.northernlighttechnologies.com/