This is a hasty conclusion. For example, the city of Kiruna in northern Sweden (latitude 67 degrees north) has about three weeks of total darkness each winter.

This is a hasty conclusion. For example, the city of Kiruna in northern Sweden (latitude 67 degrees north) has about three weeks of total darkness each winter. So there is no sun exposure at all during that time. And even south of the arctic circle, the chance of getting 5-30 minutes of sun exposure twice a week is not guaranteed in northern countries. For example, you might be stuck in an office building while the sun is above the horizon.