I believe sunshine helps PN. I live in Florida, and try to get outside everyday. I also have some auto immune diseases, and moved here for just that reason.
I took a form of therapy called Photo chemotherapy, which is just masses of ultra violet light. This helped to put my auto immune disease into remission, for long periods of time. I was in a trial study that used this as part of the therapy.
I lived up north in the cold regions and since my move south to a warmer climate I do better. It has more than Vit.D to aid you. In my case the sunshine is a help. Ask your doctor about it, he may have some ideas for you involving artificial light in the home. ginnie