One of the most important housekeeping tricks I've taught my daughters is to keep the lights low. Makes up for a multitude of sins. But I don't do this just to hide the dirt. I feel more relaxed and comfortable when I'm not sitting in a pool of harsh light. At home I run around snapping off the overheads and turning on small lamps. At the office I shun institutional florescence for incandescent alternatives.
I was thinking of all this the other day while riding Metro. The platforms are so dim that it's difficult to read small print when I'm waiting for the train. But I'm grateful for the perpetual twilight. How much worse it would be to stand shoulder to shoulder in a harsh glare. How much calmer and more inconspicuous I feel waiting in the darkness.