Many thanks for the sleep article.
It's explaining a lot.
Curtains are good, like nest lining.
I nailed an old comforter over my bedroom windows. It cuts down not only on the light (important, as I work 2nd shift and get up at 11AM), but also the outside sounds and any draft.
That last's the reason why I did it. I saw "Connections" or some other James Burke show, and he said that those beautiful medieval tapestries weren't originally created as art, but because they kept the draft out. Millenium-old tech that still works today!
That's not a terrible idea. I'm almost thinking of nailing some pretty fabric rather....maybe in such a way it can be easily attached but also rolled up, rather than just pushed aside ala curtains.