SHAFAQNA – The Grand Ayatollah Fayyaz answered a question about the timespan for a country which has no dawn or sunset.
Question: I am in Sweden and do not know how many hours I should fast.
The Grand Ayatollah Fayyaz: If the country you are living in has day, night, dawn and sunset, must act according to its religious times. But if it has not, must act according to the religious times of the nearest country.
Source: PERSIAN SHAFAQNA