This story has been updated. It was originally published on January 11, 2019.
Plastic in the ocean, greenhouse gases in the air, chemicals in the soil—we discuss these types of pollution in dinner table conversations and international media alike. But we often forget about one form of environmental damage: light pollution. Because its effects are more subtle than dirty air and water, we often fail to notice it, but the constant abundance of light can also harm our health, environment, and way of life.
“I think humanity has so far terribly underestimated the significance of manmade light from an environmental perspective,” says John Barentine, director of public policy at the International Dark-Sky Association (IDA). “What makes this issue special is that, unlike other forms of environmental pollution, it’s very easy to deal with and very simple to solve.”
By making just a few swaps, you can fight light pollution on three fronts. We can show you how to protect your personal health, darken the environment around you, and petition the nearest city to make changes for the better.
Prevent light from disrupting your sleep
The 24-hour cycle of day and night works in rhythm with our bodies, allowing a glow to signal when it’s time to sleep and when we need to stay alert. However, as we constantly subject ourselves to light, those rhythms are losing their power—and as a result, we’re damaging more than just our sleep cycles.
When you keep bright room lights shining in the hours before bed, they can suppress melatonin, a natural hormone that, among other things, helps regulate daily wake-sleep cycles. Without it, your body doesn’t get the signal that it’s time to unwind, your brain stays more alert, and you often get less sleep—which increases your risk of depression, diabetes, and heart problems. And that’s not all this hormone does. According to a study in The Journal of Clinical Endocrinology and Metabolism, melatonin disruption could raise blood pressure and possibly even increase your risk of type 2 diabetes.
[Related: How to take the best naps]
The worst offenders in our homes are LEDs. More cost-effective and energy-efficient than incandescent bulbs, they also require fewer watts to produce the same amount of light. And compared to the glow from traditional bulbs, the waves LEDs emit fall in a bluer part of the color spectrum. However, research suggests that this type of light makes us more alert and cognitively active. As a result, LED lights may disrupt our circadian rhythms more than incandescent bulbs and their rosier rays.
In fact, any blue-tinged light—including that emanating from digital screens like those of cell phones, computers, and TV—delays the onset of melatonin, reducing our sleep and harming our health. Still, we just can’t quit them: The National Sleep Foundation found that 90 percent of Americans use some sort of electronic device in the hour before bed at least three nights a week. Those who texted or used their computers in that time reported that they were less likely to get a good night’s sleep and more likely to wake up feeling groggy the next day.
Luckily, indoor blue light is a problem that’s relatively easy to fix. If avoiding screens for an hour or two before bedtime is out of the question, change the color of those screens. Apple devices, for example, offer a Night Shift setting that automatically changes the color temperature of their emitted light when the sun goes down (or at any other time you choose). Androids have a similar option called Night Light. If your device doesn’t have a built-in setting, you can find an app to do it for you.
As for the bulbs that illuminate your evening activities, swap bright white LEDs—in both indoor and outdoor fixtures—for versions with warmer color temperatures. And if you can’t eliminate all the blue light, try on a pair of special glasses that filter out blue light.
Replace your outdoor lighting
As mentioned earlier, you should swap your outdoor LEDs for warmer ones. And there are other ways to reduce the amount of light pollution you spread around. While indoor lighting disrupts our health, outdoor lighting negatively impacts animals, plants… and would-be astronomers.
Studies suggest that human lights disrupt mating and migration patterns in many animal species. For example, they distract migratory birds, drawing them off course. On beaches, they contribute to the declining sea turtle population, disorienting hatchlings and drawing them toward city streets—and nocturnal predators—rather than the ocean. Plant life suffers because moths and other beneficial insects wander toward artificial light and die rather than pollinating the greens that rely on them. Even humans might mourn: As bright lights render the stars invisible, amateur and professional astronomers have lost their view of the cosmos.
By changing your outdoor light setup, you can help wildlife thrive—and earn the thanks of any neighboring star gazers. Start by switching off outdoor lights. If you’re worried about safety, some studies suggest that outdoor lighting may have no effect at deterring crime, and that criminal activity may actually increase in better-lit areas. If that doesn’t convince you, install a motion sensor. That way, lights will only switch on when something moves nearby.
Another easy fix is to buy outdoor lighting fixtures that focus the beams. Lamps that don’t direct light in any way contribute more to light pollution, and they’re also inefficient: In 2015, the International Dark-Sky Association estimated that US residential property owners annually waste at least 117 kWh (that’d cost roughly $22 in New York) per household on misdirected outdoor lighting that does nothing but contribute to sky glow.
Replace those types of fixtures with more focused lighting, which you can find at your local home improvement stores or online. Some options even have a dark sky-friendly seal right on the box. Even without this label, you can still see whether a potential purchase will do the job: Look for directional or shielded fixtures that point light downward, so the bulb is only visible from directly underneath.
Dim your city
Reducing the light pollution that big cities emit is not as easy as swapping your light bulbs. For this, you’ll have to petition local governments to act on your behalf. Still, it can be done: Cities like Tucson, Arizona, where IDA is based, and Flagstaff, Arizona, have implemented citywide changes to protect the night, making the sky darker and the stars brighter for all.
Flagstaff led the charge in 1958, when the city passed a lighting ordinance banning sweeping searchlights. In 1972, Tucson required outdoor lighting to have shielding that directs it downward. Flagstaff did the same in 1973. Then in 1986, Tucson updated their ordinance by banning mercury vapor lights and bottom-mounted billboard floodlights. Next, Flagstaff required all roadways and parking lots to switch to low-pressure sodium lights. In 1998, Coconino County passed the world’s first code to restrict both the type of light permitted in the county and the amount of light per acre. Starting in 2016, Tucson replaced its streetlights with LEDs that emit less blue-spectrum light than most, all of them shielded and most of them with wireless connections that make them remotely dimmable.
The result? Flagstaff has one of the most accessible dark skies in the US—you can see the Milky Way from downtown. Tucson has decreased its overall sky glow by 7 percent and the total amount of light by 70 percent.
How can you bring similar changes to your city? “It’s not a technically difficult problem,” says Christian Luginbuhl, a retired astronomer at the US Naval Observatory in Flagstaff. He’s been leading the charge for that city’s dark sky-friendly ordinances since the 80s. “The reason it doesn’t get solved in so many places is that we need more cultural awareness and initiatives. The technical solutions are just a link in the chain,” he says.
According to Luginbuhl, the key factor is getting people passionate about the value of clear night skies, and how light pollution takes them away. To that end, the Flagstaff Dark Skies Coalition hosts annual star parties in the fall and year-round events—art exhibits, lectures, and musical performances—that promote cultural connection to the night sky.
You can start the journey to dim your city by creating or joining a dark-sky advocacy organization like IDA (which might already have a local chapter near you). Partner with environmental, astronomy, and outdoor-advocacy groups to spread the word about the importance of maintaining dark skies. IDA even has resources to help you get started.
Once community support and commitment exist, talk to jurisdictional authorities like commissioners, zoning boards and elected officials, explaining what people can gain by reducing light pollution. Then ask these authorities to consider city-wide ordinances and positive changes, similar to the ones Flagstaff and Tucson adopted.
- Implement lighting zones, so they can have different levels of brightness in, say, more rural versus more urban areas.
- Ban upward-facing billboard floodlights.
- Limit the amount of light (lumens) that non-residential properties can use.
- Require streetlights and parking lights to have shielded fixtures that point down, focusing the rays away from the sky.
“The only way to address light pollution effectively is that we as a society need to decide it’s something we care about,” Luginbuhl says.
This will take time, but light pollution is a problem with a clear solution. Once we solve it, the results benefit us all.