I suspect the antidepressants are because of the dark winters. (but why, I can hear you asking, isn't that the case for sweden/norway/finland? I am not sure. Just, that in the US, antidepressants seem to be associated with long dark rainy winters and enough money to afford the antidepressants.
Huh. I wonder if it is rain, not snow. My impression is that the northernmost countries get a lot of snow, but denmark and iceland mostly get rain.)