Why Protecting the Night From Light Pollution Is Good for Our Health
80 percent of people have never seen the Milky Way.
When the power went out in Los Angeles after the Northridge earthquake of 1994, residents who could suddenly see the Milky Way called Griffith Observatory director Ed Krupp, perplexed. They asked about “the odd sky” they had seen. “Gradually, it became apparent that people were talking about the night sky and about the stars,” Krupp says, adding that an estimated 80 percent of the global population has never seen the Milky Way thanks, in part, to light pollution.
The night may belong to lovers, but it’s getting so bright outside that true darkness, the “blackness of darkness” referred to in historic texts, is hard to locate. Light pollution is all around us: Street lamps shine all night, flood lights illuminate alleyways, and we lie in bed, glued to glowing iPhones. “In this broad sense we have lost this profound contact with the night sky, which not that long ago our relatives and ancestors viewed regularly,” says Krupp. “The sky is responsible for things more than beauty; it gives us perspective. Here at the observatory we preserve the stars like an endangered species. The planetarium, which is artificial, is so thrilling to viewers that they respond emotionally,” Krupp says, explaining that the sight of stars projected in the dark often prompts applause.
The paradox is that it’s the same electric light that blots out stars that allows Krupp to project them. Since Thomas Edison flipped the switch in 1879, electric light has saved lives in hospitals, allowed industrial productivity, and eventually provided entertainment in the forms of film and television, both of which rely on bulbs. While the value of light is evident, the merits of darkness are less obvious.
Darkness scares us. It represents the unknown—all things dismal and evil. It’s often described as a quality to be vanquished, or referred to in religious texts as something from which we seek salvation. Still, there is no denying that to be human is to experience darkness in all its visual and metaphoric forms. “Because no man can ever feel his own identity aright except his eyes be closed;” Herman Melville wrote in Moby-Dick, “as if darkness were indeed the proper element of our essences, though light be more congenial to our clayey part.” Plus, darkness is romantic, according to a 2013 study by the National Sleep Foundation, which found that almost 50 percent of Americans surveyed thought that darkness sets the mood, joined by far greater percentages of Germans, Mexicans, British, and Japanese.
Romance aside, darkness is essential to the biological functions of most living things, according to University of Connecticut cancer epidemiology professor Richard Stevens, who in 1987 published a paper suggesting breast cancer could be linked with nighttime light exposure. Stevens says the idea came to him as he lay in bed dejected that studies were unable to link a rise in breast cancer in industrialized nations to the modern diet. “I woke up in the middle of the night, and then I realized I could almost read a newspaper from the street light,” he says, “and that’s a hallmark of industrialization. And then I started asking about what this light can do.”
Stevens and colleagues found that exposure to light at night can suppress the production of melatonin, a hormone that protects against tumor growth. He said at least 40 studies published after his paper have found that breast cancer is between 10 and 50 percent more prevalent among female night workers. “The circadian rhythm is the cornerstone of all of our biology,” he says. “A candle in the evening will [hardly] disrupt your circadian rhythm,” but light, particularly blue-spectrum light found in newer light bulbs and electronics, “delays our night circadian biology.”
More recently, light at night has been linked with increased risk for diabetes, sleep disorders, and even obesity, Stevens says, adding that it was just a matter of time before the human health hazards of night light exposure were widely recognized. “I think maybe 10 or 15 years from now the average person is going to say, ‘Whoa, that light at night is not good,’” Stevens says. He suggests limiting electronic use before bedtime and purchasing newer smart light bulbs like the Phillips Hue that can adjust their color based upon the time of day, so that when electric light is used at night it does not mimic daylight. “In the evening you don’t want to have something that’s going to be jazzing you up,” he says.
Like Stevens, proponents of dark skies also have suggestions: They advocate for fixtures that direct all light downward and recommend motion-activated systems that apply warm light only as needed, says John Barentine, program manager of the International Dark-Sky Association. The nonprofit offers certification to locations that offer the darkest skies in the world and provides educational resources regarding light pollution. “The good thing is, light pollution is one of the only forms of pollution that is completely reversible,” Barentine says, explaining that fixing the problem on an individual level could be as simple as changing a light fixture.
As it stands, astronomers have had to retreat to remote locales in order to capture faithful images of all things celestial. Dark skies have become so rare that communities have popped up showcasing dark nights and observatories as amenities the way some developments showcase swimming pools. Barentine notes that some areas are passing local lighting ordinances, enacting rules against such things as “light trespass” as night skies increasingly become a tourist attraction.
For stargazers like Lynn Rice, darkness is a lifestyle. When she answers the phone at her mountaintop home, dogs bark in the background and she’s quick to mention that my 10 a.m. call is early for anyone serious about astronomy. Rice and her husband, Mike, who are both in their 70s, followed the stars from Alaska to New Mexico, where they now make their home. Rice explains they “got tired of winter skies” and retired in 1997, pouring their life’s savings into the purchase of 53 acres of land on the southernmost tip of the Rocky Mountains. There they “relax” in a remote town called Mayhill, on a road called Contentment Crest, where they run New Mexico Skies , a high-tech observatory.
Many years earlier, the night sky provided a backdrop to the Rices' high school romance, back when stars could still be clearly seen over their hometown of Ann Arbor, Michigan. “My husband built his first telescope when he was in grade school. He used a spool out of his mother’s sewing kit,” Rice says. “There were places you could still go when the sky was still dark. That was in 1950s, but we graduated in the 1960s, and by then it was hard.”
Today, many of the approximately 40 telescopes on the Rices’ property are owned by universities and NASA, and they offer pristine views she describes as some of the best in North America—at a high elevation, bordered by a national forest in a state that passed the Night Sky Protection Act, which governs outdoor lighting to preserve views of the night sky. “In our lifetime we will be ok,” Rice says regarding the encroachment of light pollution.
In 1964, years before NASA released satellite images of the world at night, Paul Simon sang of a rough encounter with a street light: “My eyes were stabbed by the flash of a neon light that split the night and touched the sound of silence.” On Rice’s property, darkness offers its own sensory power—and makes for great viewing. Visibility is measured by how turbulent the air is, Rice explains, noting that because the mountains on her property are very rounded, “the air flows smoothly over them like air over an airplane wing.” Looking up at the sky, “the photons that hit your eyes have traveled all that distance,” Rice says. “It's like you are looking back into time, because it took so long for the light to travel back to your eyes to see it ... It’s spine-tingling to think about.”