Nordic Countries have this problem which affects melatonin levels and human psychology. It's not a very good place. I think the best conditions are met in the Mediterranean.
It affects each person differently though. Personally, I don't notice it at all. It is a bit harder to get up in the morning if it's still pitch-dark outside, but otherwise, I have no SAD-type effects.
Others can barely function without those lamps that are white-balanced to match sunlight and programmed to gradually brighten up in the morning.
I'm inclined to think that the longer hours in summer more than make up for the shorter hours in winter. Doesn't help with sleep but for any kind of outdoor activity it can be glorious.
