Sunshine, a critical tool for writers?

We have had more than our share of dreary, cold, and wet spring days in Wisconsin. Everyone I met, family, friends, people at the grocery store, fellow gym goer—they all mentioned how they were tired of this soggy mess. I agreed with them completely.
It downed on me that it might be the reason I have done so little “new” writing in the past few days. Sure, I have worked on the stories I have already written. I have tweaked a few that didn’t need any tweaking and probably made them worse but I haven’t written brand new material on a complete blank computer screen.
It made me think that more than anything we writers, who sit in one corner and face a blank pages or a computer screen, need is that bright sunshine to flood our brain cells with intellect and ideas.
I would love to know how sunlight has any effect or not on your mood and/or creativity.