Written by Victoria Liptakova - Editor: Anastasia Eginoglou
When was the last time you lifted your head to admire the stars? Has it ever happened that, despite a weather forecast predicting a clear sky, you stepped outside only to find nothing but a dull, starless sky above? Were you perhaps near or within a city?
If your answer is yes, chances are you weren't facing clouds at all, you were witnessing light pollution. Unlike the more commonly discussed environmental problems, such as carbon emissions or plastic waste, light pollution remains a relatively silent issue. Yet, it’s just as disruptive.
To explain it simply, light pollution is the result of artificial lighting produced by human activity. The lights we install in our homes, streets, businesses, and public spaces reflect off the atmosphere and create a luminous fog that hides the night sky. This phenomenon makes it significantly harder to observe celestial bodies. Astronomers, in particular, struggle with this glow, as it interferes with telescopes and distorts long-exposure observations. From a space-based perspective, the situation is even more striking: approximately 80% of the world’s population lives under lit-up skies. Only a few spots on the planet, places like the remote forests of the Amazon, the frozen Siberia, or the sands of the Sahara, still experience darkness in its pure form.
Light pollution itself comes in several forms:
The first is known as clutter. Clutter refers to the excessive grouping of lights, causing visual confusion. One of the best examples of clutter is Times Square.
The second type is glare, which many people encounter while driving at night. Glare occurs when overly bright lights shine directly into our eyes, causing discomfort and even temporary blindness. Then, there is light trespass - an uninvited intrusion of light into spaces where it doesn’t belong. Think of a streetlamp pouring unwanted light into your home.
The consequences of light pollution extend far beyond astronomy. It is not only skywatchers who voice concerns about our over-lit world. Scientists across fields are warning us that the damage caused by artificial lighting is widespread, affecting humans and animals alike.
Our bodies, like those of many living organisms, operate on a circadian rhythm, a natural 24-hour internal clock that helps regulate sleep, metabolism, hormone production, and more. This rhythm allows us to distinguish between day and night without needing to be taught. One of the most crucial elements tied to this cycle is the hormone melatonin, which is released in the dark. When our environment is flooded with artificial light at night, melatonin production is suppressed. A deficiency in this hormone can lead to headaches, increased stress, sleep disorders, and in some cases, even links to more severe illnesses, including cancer.
Animals are not spared either. Some of the most heartbreaking consequences of light pollution can be seen in the natural world. Baby sea turtles, for instance, hatch on beaches and are naturally drawn to the brightest horizon. Traditionally, this would be the moonlit ocean. However, in today’s world, city lights often outshine the moon, leading hatchlings in the opposite direction. Instead of reaching the sea, they head toward roads, hotels, or inland areas, where their chances of survival dramatically decrease.
Nocturnal animals face a similar crisis. Species that rely on the cover of darkness to hunt or mate are now exposed during what should be their safe hours. Insects, too, are drawn to artificial lights. Many of them die upon touching the heat of the light source, and the impact on the food chain is profound, as these insects often play essential roles as prey for other creatures.
Birds, especially migratory species, are among the most heavily impacted by light pollution. Many of these birds navigate using the moon and the stars. When city lights outshine the natural glow of the night sky, birds become disoriented. They may circle illuminated areas endlessly, wasting energy, becoming lost, or colliding with buildings.
This behaviour is most commonly observed during migration seasons, in spring and autumn, when birds travel vast distances between their breeding and wintering grounds. During these times, bright urban skylines can become deadly traps. Disoriented birds crash into glass windows of houses and schools, suffering injuries or death.
A common argument in favour of lighting up our streets and neighbourhoods is the belief that increased lighting makes us safer. We have all heard that children fear the dark, but even as adults, we often assume that a well-lit street is less dangerous than a dim alleyway. But is there any truth to the idea that more lighting prevents crime?
Surprisingly, research suggests otherwise. Studies conducted in the United Kingdom have shown no substantial link between increased outdoor lighting and lower crime rates. Overly bright environments may even assist wrongdoers by making potential victims more visible. Contrary to popular belief, there is no confirmed correlation between better lighting and reduced incidents of theft, vandalism, or traffic accidents.
Furthermore, light can create psychological discomfort rather than reassurance. When asked about nighttime experiences, many women reported that overly illuminated streets can make it harder to clearly see who is approaching them. In such situations, too much light blurs vision rather than sharpening it, fostering a different kind of unease.
While the challenges of light pollution are serious, the solutions are well within reach. One of the most effective actions we can take is to redesign the way our lights function. Many outdoor light fixtures are poorly constructed, sending light upward or outward instead of focusing it where it’s actually needed - on the ground. Adjusting the angle and direction of these lights can prevent unnecessary spill and reduce glare.
Switching to warmer-colored bulbs, rather than harsh white tones, also lessens the disruptive impact on both human circadian rhythms and wildlife behaviour. Many office buildings around the world continue to leave lights on throughout the night, even when no one is working. Ending this practice would significantly reduce nighttime brightness, cut energy use, and lower costs.
As individuals, we can take practical steps, like installing blackout curtains to prevent light from leaking into the outdoors, particularly in homes located near natural habitats. Supporting wildlife by turning off unnecessary garden lights during migration seasons and learning more about local animal patterns are simple yet powerful steps. We can also spread awareness by kindly encouraging our neighbours to do the same. In addition, smart technology such as motion sensors, timers, and dimmers can help regulate lighting, ensuring it is only used when necessary.
An inspiring example of proactive change comes from New Mexico. In 2024, the company “Franklin Mountain Energy” made a conscious decision to reduce light pollution at its work sites. As a result, it became the first company to receive a certification from DarkSky International, an organisation that advocates for the protection of the night sky.
The results were impressive. Workers reported that conditions on-site actually improved, as the intense glare from previous lighting setups had been making it harder to see properly. By softening and directing their lights, visibility increased, safety improved, and electricity consumption decreased. This success story has been applauded worldwide as proof that collective action and thoughtful design can preserve our night skies without compromising progress.
Darkness, often feared and misunderstood, is not the enemy. It is a vital part of Earth’s natural rhythm, a space for rest, reflection, and rebirth. The next time you flip a switch at night, consider the unseen impact of that simple action. Perhaps the light can wait until morning. After all, a truly starry night is not something we should remember from childhood; it’s something we all still deserve to see.
Sources:
National Geographic Society (2022). Light pollution. [online] education.nationalgeographic.org. Available at: https://education.nationalgeographic.org/resource/light-pollution/.
DarkSky (2023). Light pollution harms wildlife and ecosystems. [online] DarkSky International. Available at: https://darksky.org/resources/what-is-light-pollution/effects/wildlife-ecosystems/.
DAMIANO, J. (2024). Outside lights are deadly to birds, especially this time of year. [online] AP News. Available at: https://apnews.com/article/birds-exterior-lighting-collisions-b4c164f25f86b56186d1d08bff6c1fa9.
DarkSky (2024). Outdoor lighting at night doesn’t do what you think it does to reduce crime and increase safety. [online] DarkSky International. Available at: https://darksky.org/resources/what-is-light-pollution/effects/safety/.
DarkSky International. (2024). Light pollution wastes energy and money and damages the climate. [online] Available at: https://darksky.org/resources/what-is-light-pollution/effects/energy-climate/.
LEE, M. (2025). Stargazers’ delight: Efforts to cut unwanted light pollution in New Mexico win praise. [online] AP News. Available at: https://apnews.com/article/dark-starry-skies-light-pollution-oil-industry-42a740ac52d1b307aede9560764f9bb2.