"Winter depression is still a mystery to scientists who study it. Many things, including brain chemicals, ions in the air, and genetics seem to be involved. But researchers agree that people who suffer from winter depression -- also known as "seasonal affective disorder," a term that produces the cute acronym SAD -- have one thing in common. They're particularly sensitive to light, or the lack of it." -
http://www.webmd.com/depression/features/seasonal-affective-disorder I have had a friend in NYC recommend light therapy. I guess I'll give it a go!