The trick, according to Business Insider, is to celebrate winter instead of longing for summer. Regarding the notion that many people not used to the darkness of Swedish winter might get depressed they write that:
”Swedes, however, have learned to make the most of - and even revel in - their environment. A national pastime called mys, which translates roughly to coziness, involves relaxing, getting comfortable, and eating delicious food.”
Swedes get depressions like people in other countries, but it may be true that we are good at enjoying winter.
Read the whole article at Business Insider Nordic:
http://nordic.businessinsider.com/mys-swedish-tradition-helps-cope-with-winter-2017-11/