This time of year is always rough on me. Starting in October when the days really start getting shorter right through March, I suffer from a lack of light. My depression, which is a pretty frequent companion throughout the year, definitely kicks into higher gear.
It was about three years ago that I realized that my older son suffered from seasonal depression as well. I was busy trying to fight the destructive monologue in my head and just manage to get through the day when I realized that my son was saying everything I was thinking. He had the same voices going inside his head. It was then that I realized I really needed to do something, because it was no longer just about me. It was about my child.
It was then that I tried full-spectrum lightbulbs. Within three days, both my son and I were feeling almost human. I then went out and bought more and installed them in almost every light fixture I could. Now, I wouldn't dream of trying to navigate the winter without them. They don't completely take away the problem, but they definitely help a great deal. I usually buy the GE Reveal brand (make sure you get the ones that say "full-spectrum" on the front of the box), but there are other brands. I definitely recommend them to anyone who suffers from the winter darkness.
For more information on determining if your child has this issue (especially if you don't suffer from it and don't know what to look for), please check out this article: Identifying Seasonal Affect Disorder