Polar Nights is the romantic name for what people in northern Norway call "the dark time." As I wrote yesterday, in Tromso, there is no sunlight between 25 November and 17 January. And because of the mountains, it is actually even longer - it would end on January 17 if the sun was unobstructed, but it is not.
In general, it seems like the northerners take the darkness in stride. They light a lot of candles, cook nice meals, and spend time skiing or hanging out with their families. In Oslo, at the darkest, we still have six hours of daylight, from 9:30 to 3:40 or 4, so it is very different. But for some it can still be tough! In general, people find fall harder than winter - in fall it is so obvious that it is getting darker and before it starts snowing it feels soooo dark and grey.
It is also important to point out some mitigating factors: in the north, during the middle of the day, it does get somewhat lighter - it looks like dusk is about to arrive. And the snow makes it a LOT easier to bear because the pretty white makes it look lighter.