WHO KNEW Light Pollution Has Scientists Seriously Concerned? We Should Be, Too.
Light pollution is defined as the “brightening of the night sky caused by street lights and other man-made sources, which has a disruptive effect on natural cycles”. More than 80% of the world’s population (and 99% of Americans and Europeans) live in an area affected by light pollution. This light can be so pervasive that Los Angeles’ glow can be seen 200 miles away. It impacts natural body rhythms in both humans and animals by affecting melatonin levels causing sleep deprivation, fatigue, headaches, stress, anxiety, and other health problems. Some recent studies even show a connection between lowered melatonin levels and cancer. This link to a well written article from NIH about light pollution, Missing the Dark, is worth a read: https://pmc.ncbi.nlm.nih.gov/articles/PMC2627884/
Many environmentalists believe light pollution is one of the fastest growing and most pervasive forms of environmental pollution. It impacts the migration of sea turtles and birds by interfering with the moonlight needed to guide them to their destinations, thus causing the death of many. Light pollution even affects the rest cycles of trees. It’s such a large concern that the National Park Service has set a goal of ensuring their parks have dark night skies. Many states have adopted legislation to control outdoor lighting, going so far as to urge the use of blinds, shades, and curtains to prevent indoor light from spilling outside. “There has not been one species that has been studied that has not been affected by light pollution,” said Bettymaya Foott, Director of Engagement at the Institute of Dark-Sky Association (IDA). “More than half of all species are nocturnal”.
The negative impact on insect populations, critical to keeping birds, animals, and humans alive, is large. Bees have been affected by light pollution because it interrupts their sleep patterns, disrupting their circadian rhythms, affecting navigation, foraging, and pollinating. Their overall health is negatively impacted, thus leading to reduced colony health.
Why is this loss such a big deal? 75% to 90% of all flowering plants rely on pollinators, mostly insects. Our world's food crops depend on pollinators like bees, but other insects, such as butterflies, moths, beetles, and flies, are also significant. Yet, thousands of moths are killed every night from swarming around outdoor lights, dying by morning, either from exhaustion or predation (birds and bats). In Germany, it is estimated that one billion insects die as a result of light pollution every night. https://www.sciencedirect.com/science/article/abs/pii/S0006320719307797#
Light pollution is not limited to cities and town centers. Rural streetlights, porch lights or any outdoor light that gets left on all night causes light pollution. Little evidence supports the notion that more light equals more safety. Some studies suggest the opposite, since increased lighting aids criminals more than it deters them by allowing them to see their target fully illuminated, while they hide in the shadows outside the light’s glare. Use of LED lighting, which can be dimmed considerably, as well as directional lighting to shield the impact of light, can help mitigate the negative impacts of nighttime lighting when it is used. In addition, using amber or yellow light can also reduce the impact on insects.
The next time you “turn out the lights” and go to bed, consider extinguishing your outside lights, too. Your neighbors, as well as all the wildlife, insects and plants on your property, will thank you.