i've never heard that. people who routinely live in cold temperatures eventually habituate and their bodies get used to it. your blood does not get thicker if you are cold. blood gits thicker if there is an over production of platelets or if there is some other issue with the blood. even in a cold area your body is still somewhere in the neighborhood of 98 degrees because your body burns fuel to keep itself warm. people in ancient japan for example regularly lived in unheated homes with only a charcoal brazier and thick quilts on the bed in winter. they tended to be quite healthy. the human body is amazingly adaptable.
what are the long term effects of hypothermia. if you have exposure to low temperatures either by being out in the cold a lot during winter working in a meat freezer without protection or just living on the breadline not being able to pay for heating there is a greater chance of "hypothermic" reaction. for instance blood thickens and clots form - so you survive day to day but then after a while you cant breathe as clots travel to the lungs or brain and you have a stroke. is this right - common - or just missed by most people and shrugged off