The next time it’s nighttime where you are, go outside and take a look at the sky. What do you see? Can you see the moon? Are there stars out? What constellations can you see? With more artificial lights making their way into our lives, a significant amount of people around the globe aren’t able to see many stars, let alone the Milky Way. The true darkness of night can be overwhelming and seemingly trivial but its existence is vital to people, animals, and the earth.

This inability to fully see the night sky actually comes from light pollution, a type of pollution most may not be familiar with. Light pollution is a global, anthropogenic issue and is defined as “the excessive or inappropriate use of outdoor artificial light” by NatGeo. The inventions of electricity and the light bulb were transformative and changed life as we know it but these inventions have also resulted in some harmful effects for humans and animals alike.

Why is Light Pollution a Problem?

For humans, our ability to sleep well has been disrupted by all the light we produce. Complete darkness is vital for our ability to sleep and the blue-white light that comes from LEDs and other sources further interferes with our brain’s chemistry by suppressing melatonin (the sleep hormone) and increasing cortisol (the stress/excitement hormone). Both of these hormones are natural and necessary to our everyday lives but the disruption can cause other issues. Melatonin, for example, has been linked to lower blood pressure, glucose levels, and body temperature. While cortisol is an important hormone, our bodies aren’t meant to experience prolonged high levels of cortisol. Having high cortisol levels can lead to issues like Cushing’s Syndrome, weight gain, cognitive issues like difficulty concentrating and headaches, and severe fatigue.

Note: Health care in the United States is complicated and expensive but please consult your doctor if you think you’re experiencing any sort of medical situation, including sleep issues or elevated levels of different hormones.

Animals are also affected by artificial light and light pollution in a myriad of different ways. Migrating birds use the stars and the moon to navigate while traveling at night, something that’s becoming increasingly more difficult with more and more light filling the night sky. While birds do use the Earth’s magnetic field lines to navigate, those that migrate at night also need the stars to know the right direction to fly in. Light pollution can drown out the stars and distract birds, causing them to go in the wrong direction. Going in the wrong direction or circling endlessly (another effect of light pollution) both waste crucial energy that birds need to make their journeys.

So many other animal and insect species are also affected by light pollution. Sea turtle hatchlings will use visual cues like the moon to find the sea but artificial lighting can be disorienting and can cause some to go in the wrong direction. They can easily end up in a road or parking lot because of this confusion, often causing many to die. According to the International Dark-Sky Association, a significant amount of sea turtle hatchlings die because of light pollution.

For other nocturnal animals, artificial light at night is having a negative impact on many different species. For example, prolonged exposure to bright lights can also affect amphibians’ hormones, skin coloration, thermoregulation, and reproduction. Other nocturnal animals in North America impacted by light pollution include barn owls, mountain lions, mice, opossums, hedgehogs, red foxes, raccoons, and even armadillos. Bat species are also having a difficult time with artificial light at night, as some species have an aversion to light and their foraging habits have been disrupted.


Where is Light Pollution Most Common?

Back in 2016, Sean Kane from Business Insider took a look at the areas with the most light pollution around the world and found that Europe had some of the worst. The entire continent seems to be bathed in artificial light, with more densely populated areas being the worst hit. The eastern United States also sees a significant amount of light pollution, with the urban stretch from New York City to Washington, D.C. being particularly bright. Other major and mostly urban areas around the world, like Hong Kong, United Arab Emirates, Cairo, and Jerusalem, all deal with massive amounts of light pollution.

International Dark Sky Places

The tiny island nation of Niue is actually the first ‘dark sky nation’ in the world and was named an International Dark Sky Place by the International Dark-Sky Association in 2020. There are 130 other certified places, including parks, preserves, and communities like Death Valley National Park and Moffat, Scotland but Niue is the only country to have the designation.

The island nation’s remote location in the Southern Pacific Ocean and small size (both in acreage and population) are contributors to its dark environment. But other dark sky places, Niue went through significant measures to get this status, like replacing all the street lights and upgrading domestic private lighting for the whole island.

How Can We Fix This?

Our reliance on electricity and artificial light, especially in more urban places, makes fixing light pollution seemingly impossible but there are solutions. I do think there’s a way to balance human needs and the necessity of darkness many animals require at night.

The first and simplest starts at home but it also might be controversial. Turn off lights when you’re done with them, including your porch light. Porch lights that are left on all night can emit plenty of unnecessary light. A 2015 study in England and Wales found little evidence of harmful effects related to turning outdoor lighting off, turning to partial lighting/dimming, or changing to white light. A literature review from the California Measurement Advisory Council found that there is insufficient evidence on the causal link between crime and night-time lighting but did find that there is a perception of greater safety in lit areas. Basically, we feel safer in well-lit areas but there doesn’t seem to be a link between outdoor lighting and a reduction in crime. (One way to reduce home burglaries is to actually introduce yourself to your neighbors and have good relationships with folks in your neighborhood or apartment complex.)


A second solution would be to replace any and all inefficient types of lighting with ones that don’t result in light going everywhere. Fixtures that encase bulbs and cause light to shine where it’s needed (and not up into the sky), lower wattage bulbs, and motion sensor lights can all reduce light pollution while also providing some functionality and safety. Decorative lighting for festivities and celebrations can also be used for shorter intervals (and not left on all night). This solution can make it possible to have artificial light on at night in some places without causing too much light pollution.

The International Dark-Sky Association also has a list of general rules to follow with outdoor lighting to help reduce artificial lighting in the outdoors. Low glare fixtures and lighting with lower color temperatures are both great options for outdoor lights. Plus, only using the lights when and where you need them can limit the amount of light pollution you might produce. Reducing the use of decorative lighting, like for Christmas or other holidays and celebrations, can also help conserve energy and limit light pollution.

Light pollution might be something you have heard about but if you have ever lived in an urban setting, it’s definitely something you’ve experienced. While it may not seem important, a dark night sky actually provides both beauty and functionality, as humans and animals alike have used the stars and moon to navigate for millennia. For those in developed and urban areas, the idea of tackling light pollution may seem daunting but there are doable solutions, like turning off lights and using more effective technology, that limit light pollution and conserve energy.

Being able to see the night sky and Milky Way in all its glory is an incredible experience. Personally, I’ve been lucky and privileged enough to see the night sky far away from big cities on more than one occasion and those experiences have really stuck with me over the years. If you are able and willing to (particularly after Covid-19 is less of a threat), try to visit a designated Dark Sky Place (or similarly dark area) and look to the stars.