I have absolutely no problem with writing the first draft of a novel when I'm squiffy, always provided of course that I can still see - and hit - the keyboard. When I am revising, however, which is most of the time since I need to do plenty of re-writes, I need to be absolutely stone cold sober. I guess that's because it's a totally different process. At the moment of creation drink is the catalyst as I drown in the primordial soup; during the stern revision process when I slice through the silliness and drivel drink is the reward to which I look forward with eyes filled with longing. Naturally this leads to a certain asymmetry in my writing productivity, but if it's a fine full-bodied red that's interrupting the creative process , so what.
On the other hand I'm perfectly content to write - unrevised - entries into my blog after a few glasses of red and I'm usually quite pleased with the result.
Until I read the blog again the next morning, that is. Still, maybe it's better to write something -anything - than drown in wine-filled silence.
I guess I'll find out - somewhat fuzzy-headed - tomorrow.