Is there a "minimal night length" for Ramadan timing?

I had a few discussions today regarding Ramadan (as it is ongoing now), and one of them was about the extreme places in the world where the sun does not set, or is up all the time. We found out that this is addressed by adhering to the time of a reference country. But then came the problem of places where the sun almost sets, then further south sets for a short time, and then the night gets longer and longer. Is there a night length that makes the place "follow the local time"? I can hardly imagine this when the night is 10 minutes long, or one hour, but maybe 3 hours could be acceptable. Is this regulated a way or another?