You may have seen articles on this subject by Harry Pearman in SPRING Times. The latest is on page 16 of ST63 at http://spring.parkinsons.org.uk/images/stories/SpringDigest/2012/ST63.pdf
There is an article in the Guardian of Saturday 5th May 2012 which is relevant and speaks of other conditions which have been associated with Vitamin D deficiency: http://www.guardian.co.uk/society/2012/may/05/vitamin-d-deficiency-sunlight-health
This is an area of health research we should keep an eye on.

having moved to extremely sunny australia i can definitely say that more sunshine helps and that it isn't a cure either. I've heard from a lot of pwp that they feel better as soon as they step outside.

Just confirming what someone else has said.I lived in Australia for 6 months last year and my PD symptoms were much better controlled and i could walk and do a lot more.Being out in the sun defintely helped significantly.Having been back in the UK for 6 months,I notice the difference.

been a cloudy day or two here on the new england tableland (so called because of the rocky outcrops that look like cream teas) and i can report feeling a bit ropey.
fortunately it will get sunny again on sat,sun, mon, tue but still a wintry 14 - 15 degrees. dont forget the cod liver oil for rainy days.

wonder how the australian gov would treat a boat load of pd weather-refugees? not very well i'm sorry to say.

'the passenger's declared they were not shaken by the government's attitude but has only stiffened their resolve. Some found it difficult to swallow, but refused to take a step backwards or in any other direction. '
A spokesperson for the passengers said, 'Australia is the 'In' continent, and we feel we can contribute to that.'