Opinion: Bright Nights, Big ProblemsWhy we should turn off the lights and appreciate the dark.By Paul Bogard, for National GeographicPUBLISHED JULY 20, 2013 Chicago at night burns bright under blankets of clouds.An aerial view of Chicago at night. PHOTOGRAPH BY JIM RICHARDSON, NATIONAL GEOGRAPHICWe live immersed in artificial light.RELATED CONTENT80 Percent of Americans Can’t See the Milky Way AnymoreWith Light Pollution, Perseids Meteors Less SpectacularBest Night-Sky Pictures of 2013 NamedAstronomers rate the darkness of our skies on a scale (the Bortle Scale) of 9 (brightest) to 1 (darkest). Most of us spend our lives in the radiance of levels 5 through 8, only rarely venturing into areas ranked 3 or darker. Because of the rapid growth of light pollution over recent decades, most Americans under 40 have never known real darkness. All over the globe our nights are growing brighter, and almost nowhere are they growing darker.We are just beginning to learn the true cost of all this light. Studies increasingly link our overuse of light at night with health concerns such as sleep disorders, diabetes, obesity, and cancer. Other studies report the damaging ecological consequences, the tremendous waste of energy, and even the decrease in safety and security. But the steady loss of darkness from our lives is not easily measured, for like the similarly endangered qualities of solitude and quiet, the true value of darkness is something we are barely aware of.
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