Cities Try to Turn on the Dark

Electric light has made cities eminently more functional, and visually riotous, than they otherwise would have been. It's the externality that no one seems to mind. Satellite photos of nighttime in the United States, revealing vast lightening-colored blobs and streaks, testify to the ways that we have altered the visual landscape. What is good for functionality may not, however, be good for human health, the environment, our sense of wonder, and even our safety. 

Emerging research suggests that our constant flood of light is, via hormonal disruption and sleep disorders, doing awful things to our metabolism and overall health. It confuses animals and creates a "monochrome canopy of muted light grey to almost-but-not-quite-black, dotted, depending on the size of your city, with a dim handful of stars." Surprisingly, excessive light may not make cities more safe or easier to navigate. It turns out that the human eye responds more to contrasts -- whatever the background level of light may be -- than to brightness as such. 

A new generation of architects, planners, and lighting designers are figuring out ways to light cities and buildings more smartly, efficiently, and attractively, without incurring the glare and leakage that characterizes the majority of outdoor lighting. "The trick is to illuminate change—steps, doors, paths—rather than entire landscapes."

“There is no universally applicable conclusion that comes out of criminology research that shows that more light means less crime.” Overlighting, in fact, can be worse than dimly lit spaces for several reasons, beginning with the risk of glare. As USC Professor Travis Longcore put it, “If you have bright lights, the shadows become much darker.”