All life evolved to the steady rhythm of bright days and dark nights. Today, though, when we feel the closeness of nightfall, we reach quickly for a light switch. And too little darkness, meaning too much artificial light at night, spells trouble for all.
Already the World Health Organization classifies working the night shift as a probable human carcinogen, and the American Medical Association has voiced its unanimous support for light pollution reduction efforts and glare reduction efforts at both the national and state levels. Our bodies need darkness to produce the hormone melatonin, which keeps certain cancers from developing, and our bodies need darkness for sleep.Sleep disorders have been linked to diabetes, obesity, cardiovascular disease and depression, and recent research suggests one main cause of short sleep is long light. Whether we work at night or simply take our tablets, notebooks and smartphones to bed, there isn t a place for this much artificial light in our lives.
The rest of the world depends on darkness as well, including nocturnal and crepuscular species of birds, insects, mammals, fish and reptiles. Some examples are well known the 400 species of birds that migrate at night in North America, the sea turtles that come ashore to lay their eggs and some are not, such as the bats that save American farmers billions in pest control and the moths that pollinate 80% of the world s flora. Ecological light pollution is like the bulldozer of the night, wrecking habitat and disrupting ecosystems several billion years in the making. Simply put, without darkness, Earth s ecology would collapse . . .
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