National Geographic – Electric lights have revolutionized our lives, but as illumination increases, the toll on wildlife and human health is becoming harder to ignore

…But if light bulbs have a dark side, it’s that they have stolen the night. The excess light we dump into our environments is endangering ecosystems by harming animals whose life cycles depend on dark. We’re endangering ourselves by altering the biochemical rhythms that normally ebb and flow with natural light levels. And in a primal sense, we’ve lost our connection to nighttime skies, the tapestries into which our ancestors wove their star-studded stories, timed the planting and harvesting of crops, and deduced the physical laws governing the cosmos…”