The Enormous Environmental Consequences of Artificially Lighting Up the Night
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Plants, animals and humans developed with an internal clock — the circadian rhythm. It's a 24-hour cycle that affects physiological, biochemical and behavioral processes in almost all organisms.
Civilization brought with it artificial light to homes in every village, town and city across the world, and as more buildings and factories came online, industrialization increased and the population continued to expand, our nighttime sky looked a lot like the day, changing our deep, dark sleep patterns and altering that 24-hour internal timekeeper.
With that, all living creatures' lives changed in ways only now becoming clear to us.
Dawns the light
To understand light pollution, it's important to know there are two different types: First, there is astronomical light pollution that obscures the view of the night sky, and the second kind is ecological light pollution, which alters natural light systems in terrestrial and aquatic ecosystems.
"Light pollution started to be identified in the 1800s when we realized that birds flew into the sides of lighthouses and consequently died," says Travis Longcore, science director of the Urban Wildlands Group, research associate professor at the USC geography department and a lecturer at the UCLA Institute of the Environment in Los Angeles. (Beginning in the 1940s, radio and television towers become "the spiral of death for birds that regrettably hit the guy-wires," he added.)
Twenty years later, it was discovered that artificial coastal lighting in Florida was disorienting and disrupting the rhythm of sea turtles that bury their eggs in the sand. When the eggs hatch, the hatchlings must go toward the water and beachside nests for their survival, but the babies were being distracted by the light and diverted from their natural course, often ending up facing dehydration, being eaten by predators or even wandering along the highway.
As more animals encountered night lighting, it became evident that while night light might benefit people, it wasn't helping wildlife.
Light pollution has had disastrous effects on migrating birds, resulting in millions dying each year, and that figure increases with the combination of outdoor light and fog. Birds use the light at the horizon to migrate at night. When the birds see a brightly lit building, they become confused and fly around and around — in essence becoming trapped in the light — eventually dropping dead from exhaustion.
The term photopollution — artificial light that has adverse effects on wildlife — was coined in a watershed paper by Dutch ecologist F.J. Verheijen in 1985. In the paper, Verheijen says that many nocturnally active animals need a natural light field between sunset and sunrise as a requirement for survival.
"When we think about the night and the extent of light pollution in the last 20 years, it's growing far faster than the human population and has changed the environment significantly," explained Longcore.
But light pollution's harmful effects aren't restricted to animals.
"Women who work at night, change shifts often or don't get proper sleep at night suppress their melatonin production and have higher rates of breast cancer," explained Dr. Mario Motta, president of the Massachusetts Medical Society and associate at the North Shore Cardiovascular Associates. "It's a fact. The exact cause is speculative, but we think it's because of the changes in the melatonin production due to disruption of their circadian rhythm."
Disrupting the circadian rhythm can cause insomnia, depression and increase the risk of cancer and cardiovascular disease.
Fallout from the disruption of your circadian rhythm can be harsh medicine to swallow, but so can simply living in the glare of the night's lights. Straining to see at night in the face of glare from oncoming traffic or streetlights that shine over the landscape can be irritating and uncomfortable, but it also can be dangerous.