Every year. Starts to ramp up when the days get shorter and colder. Lasts until real Spring without snow comes. I never had it until I moved to the Midwest. When it gets really bad, I use a light in the morning to help me. This is nothing like jet lag. It’s just a dreariness sort of feeling, like there’s a cloud hanging over my head. I consider myself and optimistic, pretty happy person, but when winter approaches, I have to fight for myself to stay above the fray of this disorder.
The upper midwest can be rather dreary during this time of year. We can go a month or so without seeing the sun at times..