I have S.A.D. I'm typing this while sitting under my light therapy lamp as a matter of fact! Winter is always a really hard time for me. The unrelenting gray skies where I'm living at this time and the short days - so much darkness. I hate it and it affects my mood pretty strongly. I upped my Vitamin D intake last year as bloodwork determined I was seriously deficient, bought a "sunrise" alarm clock, and this therapy light lamp. Here's hoping! Apparently my first winter (this is my 3rd) in this area of the U.S. affected how badly depressed I got to the point that a co-worker noticed it and was really worried about me.

Look in to some of the things that I mentioned - maybe they will help you, too.