Dark side of bright lights

YOUGAL SAPKOTA Research Scholar Centre for Atmospheric and Climate Sciences Environmental Engineer

Remember the mesmerizing dance of fireflies on warm summer nights? Or the breathtaking expanse of a star-studded sky, where countless celestial bodies sparkled against the darkness? These once-common sights are fading, replaced by a hazy glow that obscures the natural beauty of our world. While air, water, noise, and soil pollution rightly dominate headlines, a less visible but equally insidious threat is rapidly escalating: light pollution.The stark reality is that stars are becoming increasingly elusive. The once-familiar constellations are now often shrouded in a veil of artificial light, leaving only the brightest stars visible. This phenomenon isn't just a matter of lost aesthetic beauty; it's a symptom of a deeper environmental problem.

Light Pollution and its effect

Did you know the glow of Los Angeles' city lights can be seen from an airplane 200 miles away? That's according to the International Dark-Sky Association (IDA). In most big cities, seeing a truly starry night means going to a planetarium.In fact, after a 1994 earthquake in Los Angeles caused a blackout, panicked residents called emergency services about a strange "giant, silvery cloud." It was the Milky Way, something they'd never seen due to the city's bright sky glow. While artificial light has improved our lives by extending our days, too much of it becomes a problem. When outdoor lighting is wasteful, annoying, and unnecessary, it's called light pollution. Many experts consider it one of the fastest-growing environmental issues. Many environmentalists, naturalists, and medical researchers consider light pollution to be one of the fastest growing and most pervasive forms of environmental pollution.Light pollution comes in many forms, including sky glow, light trespass, glare, and over illumination. Sky glow is the bright halo that appears over urban areas at night, a product of light being scattered by water droplets or particles in the air. Light trespass occurs when unwanted artificial light from, for instance, a floodlight or streetlight spills onto an adjacent property, lighting an area that would otherwise be dark. Glare is created by light that shines horizontally. Overillumination refers to the use of artificial light well beyond what is required for a specific activity, such as keeping the lights on all night in an empty office building.Light pollution is increasing globally, in both developed and developing countries. Satellite data show that from 2012 to 2016, continuously lit areas brightened at a rate of 2.2% per year.(Kybaet.al., 2017).Lets look at some of the impact of light pollution in details.

Circadian rhythm and human health

Richard Stevens, a professor and cancer epidemiologist at the University of Connecticut Health Center, explains that for biologic effects to occur, light photons must reach the retina. In environments with high levels of artificial light at night, the retina is exposed to more photons, which can disrupt the circadian rhythm.

The circadian clock, which follows a 24-hour day/night cycle, regulates essential physiological processes in nearly all organisms. These include brain wave patterns, hormone production, and cell regulation. According to Paolo Sassone-Corsi, chairman of the Pharmacology Department at the University of California, Irvine, disruptions to the circadian clock have been linked to several medical disorders, including depression, insomnia, cardiovascular disease, and cancer.The connection between artificial light and sleep disorders is fairly intuitive. A misaligned circadian rhythm can lead to conditions such as shift-work sleep disorder, which affects individuals who work rotating or night shifts, and delayed sleep-phase syndrome, where people struggle to fall asleep early and have difficulty waking up for work, school, or social obligations.Research also suggests a link between artificial light exposure, night shifts, and an increased risk of colorectal cancer. In a study published in the Journal of the National Cancer Institute on June 4, 2003, Schernhammer and her colleagues analyzed data from the Nurse’s Health Studies cohort. They found that nurses who worked night shifts at least three times a month for 15 years or more had a 35% higher risk of developing colorectal cancer. Additionally, prolonged exposure to artificial light at night may contribute to a higher risk of depression and other mood disorders.

Disrupting the ecosystem

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, for nocturnal animals ,the introduction of artificial light probably represents the most drastic change human beings have made to their environment.Predators use light to hunt, and prey species use darkness as cover, Kyba explains. Birds that migrate or hunt at night navigate by moonlight and starlight. Artificial light can cause them to wander off course and toward the dangerous nighttime landscapes of cities. Every year millions of birds die colliding with needlessly illuminated buildings and towers. Migratory birds depend on cues from properly timed seasonal schedules. Artificial lights can cause them to migrate too early or too late and miss ideal climate conditions for nesting, foraging, and other behaviors.Many insects are drawn to light, but artificial lights can create a fatal attraction. Declining insect populations negatively impact all species that rely on insects for food or pollination. Some predators exploit this attraction to their advantage, affecting food webs in unanticipated ways.

Fireflies communicate in a language of light

Insects act in coordination with natural light regimes and are sensitive to changes in light intensity, wavelengths, sources and other factors. Nocturnal insects perform various activities such as foraging, reacting to predators, or navigating using the stars and moon. For insects of the family Lampyridae, commonly known as fireflies, low light is needed for reproduction.In the presence of artificial light, fireflies are forced to expend more energy in trying to flash brighter and have their signals noticed by prospective mates, although the effects vary among species which are receptive to different wavelengths.

A researcher, Ramesh Chatragadda, from the National Centre for Coastal Research attempted to record the population of Absconditachinensis firefly species in a specific area in Andhra Pradesh. In the study village, Barrankula, fireflies in a 10-meter area went from 500 in 1996 to 10-20 in 2019.(as shown in image , illustrated by Mongabay).

Every day needs a night

It's high time we treat light pollution as a serious issue and take action. Here are some best practices recommended by DarkSky.org that can help mitigate its effects:

1. Use energy-efficient LEDs and compact fluorescents (CFLs), but opt for warm-colored bulbs to minimize environmental impact.
2. Install dimmers, motion sensors, and timers to reduce overall illumination levels and save energy.
3. Choose outdoor lighting fixtures with shields to minimize glare and prevent light from spilling into unintended areas.
4. Switch to LED lighting, which allows for lower illuminance without compromising visibility.
5. Turn off unnecessary indoor lighting, especially in empty office buildings at night, to prevent excessive light leakage into the night sky.
6. Avoid using blue lights at night, as they can disrupt natural sleep cycles and contribute to light pollution.

Light pollution is more than just an inconvenience, it disrupts ecosystems, affects human health, and dims the natural beauty of the night sky. From disorienting wildlife to interfering with our sleep cycles, its consequences are far-reaching. However, by adopting responsible lighting practices, such as using shielded fixtures, warm-colored LEDs, and motion sensors, we can significantly reduce its impact. Protecting the night isn’t just about preserving darkness; it’s about restoring balance to our environment. The time to act is now, small changes in our lighting habits can make a big difference for future generations.

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