It is interesting you mention the lack of sunlight. There is an interesting study linking PD to Circadian Rhythms, so I wonder if that harsh resetting of their internal clock may have something to do with it rather than the cold?

There is some clinical support of the circadian theory through a four year study. Inhibiting melatonin production through light therapy for an hour a day resulted in improved PD symptoms and it seems to halt progression. I am not sure how that it all works together but it looks like the pineal gland is now being looked at in a range of diseases.

Laura

BTW I actually feel worse in heat and humidty; the higher the air pressure the worse I feel.