Judith H. Dobrzynski misses nighttime:
It's hard not to notice that much of the world is ablaze in light even after the sun goes down. According to the United Nations, 2008 was the first year that more than half the world's population, some 3.3 billion people, was living in urban areas. Bigger cities mean more light at night from streetlamps, neon advertising, office lights kept on, bright stadiums.... (Across the U.S., you can see for yourself how the night has changed alreadyand how it may get worse.) Not only does all this light pollution obscure the stars, create driving hazards, and cause insomnia, but it can also disrupt animal-behavior patterns and confuse birds, which end up colliding more frequently with tall structures. Plus, there's all that the wasted energy to consider.
The Dish has tackled this subject before.