My husband used to get this pretty bad when his schedule meant he was indoors literally from before first light until well after dark during the winter. Vitamin D helped a bit, but it only really got better when he could be in regular daylight hours again. It's not a pleasant thing at all.

Never noticed I had it until I moved from Florida to Montana (duh). I learned to look forward to spring. I didn't do too much for it except that I was on Zoloft at the time and got daylight light bulbs for all the fixtures in the house.

My mother moved our family to Florida when I was younger because of her SAD.