Every single year Seasonal Affective Disorder (SAD) affects so many people and we don't even realize it's happening. SAD sneaks up on people around October and sometimes it lasts all the way until April.
This is almost as sad as those Sarah McLachlan commercials. A guy noticed a kid having a bad Saturday, and narrated what was going on as the kid was looking for his friend to play with. I think we've all been that kid at some point.