Off the top of my head - I have a friend who suffers from SAD, and he swears by his light box, a special box that emits 'natural' light at a high intensity. He has it in his office to compensate for the long Aberdonian winters. I have heard others suggest St John's Wort as a herbal remedy, keeping up with your B and D vitamins, and avoiding alcohol and caffeine. My favourite remedy - one that helps with a great deal of 'illness' - including depression, back pain, and obesity... Get outside, take some daily exercise in as natural and sunny environment as you can - even winter cloudy skies are better than sitting indoors in the dark. Kick start your day with 30 minutes of pro-action, and everything else slots easily into place. Finding the motivation to get out there is the hard part.
Some more research and a Hub I think, cheers for the prompt frogdropping