Insomnia. I don't remember the whole plot, just that Al Pacino was trying to solve a murder in northern Alaska, but he was slowly losing his mind because he couldn't sleep when it never got dark. Other characters had no trouble sleeping through the "midnight sun." My reaction was "I should try that. I wonder if I could sleep or not." Natural response, yes?
Many years later, I flew from Newark to Hong Kong. I was curious of which route we'd take, whether we'd fly east or west. A route I never considered was north, but that's exactly what we did - we flew north over Greenland, over the Arctic Circle, then south through eastern Russia. Since I made the flight route in May and June, fairly close to the summer solstice, it was sunny the whole time, all 16 hours of it.
The flight attendants closed all the window blinds on the plane to keep it as dark as possible, but my body knew it was still daylight, and I managed about a 20-minute nap, even with the blinds closed and wearing an eye mask.
So I have the answer to the question raised by the movie, and if I stayed in that environment long enough, I would surely be like Pacino's character and slowly develop bloodshot eyes, and a diminshed mental ability.
Ergo, knowing I can't sleep when it never gets dark, I should cross #22 off my list because it was added to test a hypothesis. I'll leave it for now though. I want to visit every state and probably race in each one. Surely some town has a midnight sun race.