I stumbled upon this article today in the NYTimes about how walking in nature helps raise ADD children's scores.
I taught once in a school building that was built in the '50s (that is just my guess, based on barely remembered color schemes, and postwar architecture) when the prevailing wisdom dictated that windows were bad (a tragedy, because is school was situated in the golden, rolling, oak studded foothills of Northern California). The rooms were like big boxes, with only a door. I felt something was wrong when I stepped in, but it wasn't until I was chatting with my boss about the room feeling claustrophobic when she pointed out to me that there were no windows.
That was the year I let the kids paint themselves black...
(ed note-- I did some digging on the internet and found a picture of the exterior of the school-with-no-windows. This is the actual building. The foyer is totally glassed, but the classes don't have any windows.)