Some major kewl info on creativity found on the website of Charlotte Rains Dixon called "This is Your Brain When it is Creative", here. At least for jazz musicians, an MRI has shown that creativity is like a dream state: "Creativity in the form of jazz improv utilized the same parts of the brain as dreaming. First of all inhibition switched off and then self expression switched on. The musicians also showed heightened sensory awareness, with areas associated with touch, hearing and sight lighting up."
While the areas may turn out to be different for writing and art, the implications are staggering. Are we at last onto the source of the wellspring of our creativity, and on our way into tapping into it directly, not just by chance?