I wanted to agree with that workout for your brain comment but in a different context: A few years ago I was participating in "National Novel Writing Month". Normally I don't try to be creative at all (successfully utilizing Linux in a lengthy project not withstanding) but for the 30 days of November I wrote for four hours a day creatively for the whole month (the goal is 50k words in 30 days. I finished in about 27). About two weeks in I started having some really weird/messed up dreams.
I was thinking about this recently and it occurred to me that if my leg or arm muscles have a burning sensation after a work out at the gym or running seven miles it makes just as much sense for the equivalent to happen to this grossly under-utilized region of my brain. Exercising of this "muscle" that doesn't normally get any exercise should result in some equivalent sensation as a result. I mean it makes sense.
This story also made me wonder about this affect int he context of a good, stimulating TV show like the little-known Damages. I've always thought of it as pretty much as close to a "visual novel" as you'll ever see. It wouldn't surprise me if the same study was done to somebody who just watched a season of Damages straight through with no ads showed the same sort of brain activity as those that just finished a book.