Two-thirds of people in the US can’t see the Milky Way from their homes. The stars that shape our galaxy disappear from view due to outdoor lighting which is too bright, stays on all night, or illuminates the sky rather than the earth. Night lighting also interferes with the rhythms of human, animal, and plant life.
Artificial Lights Disrupt the World’s Ecosystems
Nocturnal animals sleep during the day and are active at night. Light pollution radically alters their nighttime environment by turning night into day.
According to research scientist Christopher Kyba, “Predators use light to hunt, and prey species use darkness as cover. Near cities, cloudy skies are now hundreds, or even thousands of times brighter than they were 200 years ago.” As Kyba says, “We are only beginning to learn what a drastic effect this has had on nocturnal ecology.”
“We are only beginning to learn what a drastic effect this has had on nocturnal ecology.”
Human Circadian Rhythms
Our biological clock, or circadian rhythm - the sleep-wake pattern regulated by the day-night cycle - can also be disrupted by artificial light at night. Our bodies produce the hormone melatonin in response to circadian rhythm. Melatonin helps keep us healthy with antioxidant properties that induce sleep, boost our immune systems, and lower cholesterol, among other things. Nighttime exposure to artificial light suppresses melatonin production.
A particular culprit is light-emitting diode streetlights. These are considered eco-conscious because of their bluish LED lightbulbs, which use about 50 percent less energy. The American Medical Association has released a report that's critical of LED, mentioning the glare factor and the health effect of too-bright lights on circadian rhythms.
What you can do
Inspect the lighting around your home, and use dark sky friendly lighting at your home and business. Light pollution is easy to control, simply by turning the lights off, dimming them, or pointing light fixtures downward.
For more information, visit the International Dark Sky Association website.