"Yes and lack of sunlight is also implicated. How do you get yours in the Northlands in the winter my dear? :)"
-The lack of sunlight, yes; but I do well, as I utilize every ray of it, whenever possible.
- Been to the southern US, where most only see the ray`s when they move from the car to the shop, like 100 meters.. because if longer, they drive:)
From your link, MS seem to be rare in Asia and other eastern countries. Been there too, they are outside most of the time.
So, yes a connection, most likely.