I find the 24 hour darkness easy to get used to. If you live in the north your nomal life in winter is to get up in the dark, drive to work in the dark, work inside all day while it’s light, then drive home in the dark. It’s the same here but it’s dark at lunch as well.
Getting used to 24 hour daylight is tough. You have to be careful, because if you are near a window in the evening it’s easy to lose track of what time it is. I’ve been many times chatting in one of the lounges, thinking it was 10 or 11pm, only to find it was 1 in the morning. It’s so weird having to wear sunglasses at midnight.