Light Pollution – The Dark Side of the Light, a focus on diminishing Urban Night Skies

Most of Earth’s toxic pollution comes from manmade inventions. Likewise, the invention of electric lightbulb, which is believed to be one of the greatest human inventions, has created a new problem called Light pollution. Artificial light at night has revolutionized the way we live and work outdoors, but it has come at a price.

Light pollution is excessive, misdirected, or obtrusive artificial (usually outdoor) light.

Too much light pollution has consequences: it washes out starlight in the night sky, interferes with astronomical research, disrupts ecosystems, has adverse health effects and wastes energy (Light pollution, n.d.). Light pollution is typically a side effect of economic development, population growth and urban sprawl, due to the greed for increased productivity which resulted in prolonged hours of work. In recent years, interest in light pollution has gained momentum. Appreciation for dark skies enters the consciousness of society.

Most living beings are biologically dependent on the recurring 24-hour rhythm of light and darkness, called the circadian cycle. New science shows that the absence of darkness affects not only the sleep but can also lead to an increased risk of diabetes and cancer. Advances in lighting technology have slowly flooded our world with light, and artificial lighting of buildings , streets, signs, parking lots and open spaces now dominate city nightscapes. (Insulander, 2012)

As light pollution becomes more prevalent, the ability of humans to view and enjoy the night sky diminishes. This has subtle but significant cultural impacts, especially for future generations.  However, in contrast to other pollution, the negative effects of light pollution can be mitigated easily and cost-effectively. The use of sustainable lighting is often an indirect consideration of the negative aspects of lighting pollution.

Light pollution is one of the few completely and instantly reversible forms of pollution. Cities all over the world are now realizing the benefits of eliminating this energy waste through higher quality, better-designed lighting.

Light Pollution Sky

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Some of the Negative Consequences of Light Pollution

On Humans

  • Disturbs circadian rhythms: One of the results of light pollution is increased exposure to both indoor and outdoor artificial light-at-night (ALAN). Scientists are just beginning to understand the negative impacts that prolonged exposure to light during the night may have on human health. In almost all organisms, the circadian clock, or 24-hour day / night cycle, affects important physiological processes, including brain wave patterns, hormone production (melatonin), cell regulation, and other biological activities. Disruption of these important biological processes are associated with sleep-wake disorders, psychiatric disorders, cardiovascular diseases, immunological disorders, metabolic disorders, obesity and cancer progression. Studies show that the circadian system is most sensitive to short wavelengths, such as blue-rich light emitted from LED lighting at nighttime. In 2012, the American Medical Association has recognized light at night as a carcinogen and a health risk. (Filmer, 2013)
  • Affects the production of Melatonin hormone causing breast cancer: Melatonin is a natural hormone produced by darkness, and inhibited by light. This performs several roles within the human body, primarily regulating the daily cycles of our systemic activities.
  • Sleep disorders: Exposure to the artificially extended daytime of our lighted modern world can lead to desynchronization of our internal rhythms. According to the National Institution of Health (NIH), a shift in our clocks impairs our ability to sleep and wake at the appropriate times and leads to a decrease in cognitive and motor skills. A good night’s sleep helps reduce weight gain, stress, depression, and the onset of diabetes. The NIH claims that humans function best when they sleep at night and when they behave during the day. If ambient light comes through your window and disturbs your sleep, it is recommended that you shut out the light or request that the light must be shielded for everyone’s benefit. (Filmer, 2013)
  • Security risk (Exaggerated darkness): In ancient times, and even in some modern warfare, an effective strategy involves bright lights at night. If a bright light is positioned in front of your troops, the enemy is effectively blind to anything happening behind the light. In addition, the light disrupts the enemy’s night vision so, when your surprise attack commences, they could be visually impaired. In today’s society, the principles still apply for over lighting in our cities. People with nefarious intentions can use the light to their advantage by hiding in the negative space created by the blinding light. In addition, by positioning themselves in dark areas (like ally-ways) they can become very difficult to see for someone who needs to cross through the ally for whatever reason. This is yet another problem that can be combated with fully shielded lights that are designed to cast light specifically where it is most effective. (Filmer, 2013)
  • Impacts astronomy: Artificial lights pose problems for scientists and researchers who want to observe and document objects in the night sky. Light pollution makes the sky brighter and makes it harder for them to take a smooth spectra. Their ability to study the night sky has been hindered by the overwhelming number of bright city lights.
  • Night sky heritage: Stargazing has been a human pastime since ancient times. The ancients interpreted constellations and arrangements of the stars and planets that they saw in the night sky to have important meaning for themselves and their families. As light pollution becomes more prevalent, the ability of humans to view and enjoy the night sky diminishes. This has subtle but significant cultural impacts, especially for future generations.

On Fauna

  • Affects migration, reproduction, mating, and general behaviour of birds.
  • Disruption for freshwater & marine life (mainly sea turtles).
  • Disturbance for amphibian reproduction (example: frogs).

On Flora

  • Indirect impact: Kills insects & reduces the number of successful pollinations in flowering plants.
  • Confusion for proper plant growth.

On Environment

  • Wastage of energy and Increase in Green House Gas emissions.
  • Contributing to the urban heat islands.

How are Planners and Local Authorities Responsible for It?

There is a quote which explains our world ‘s relationship between causes and effects. We have to act locally, and think globally. This means that identifying and acting through the problems we know at a local level, perhaps a region, a municipality, or even on our yard, is extremely important. Those issues are probably another problem that spreads across the globe, affecting other regions. Although light pollution is regarded as a global problem, a typical issue occurred in towns or urban clusters in particular. As the light stretches kilometres away, forming a web that constantly expands to collect others and eventually we watch the sky at night seeing nothing but a huge cloak. Nocturne landscapes are as critical as day landscapes.

How to Reduce Light Pollution?

The International Dark-Sky Association (IDA) is a United States based non-profit organization established in 1988 with a vision of having the night sky, filled with stars, being celebrated and protected around the world as a shared heritage benefiting all living things.

Their impact has now reached 51 countries. However, the problem of light pollution continues to grow. Light pollution is increasing worldwide at twice the rate of global population growth. Eight out of ten people live under a light-polluted night sky, at least three billion dollars is wasted on outdoor lighting each year in the U.S, and virtually every species studied has been harmed by light pollution.

The IDA suggests the world a four step plan in order to reduce light pollution and conserve light pollution (International Darksky Association, 2019). They are:

  1. Celebrate The Night: Increase awareness of the benefits of the dark sky to all living beings and how light pollution is an urgent environmental threat that individuals can help to solve.
  2. Dark Sky Protection: Protect exemplary dark skies through the International Dark Sky Places conservation program, which recognizes and promotes excellent stewardship of the night sky to encourage communities, parks and protected areas around the world to preserve and protect dark sites through responsible lighting policies and public education.
  3. Lighting Where We Live: Engage cities and communities in reducing light pollution through responsible lighting policy/ordinance and practice.
  4. Sky shed Restoration: Implement coordinated, intentional, and scalable actions to slow, halt, and reverse the increasing rate of light pollution


Although many countries are still unaware of the light pollution, it will increase the impact of light pollution over the years. The main aim of this research is to bring awareness about the negative consequences of light pollution and to recognize the dark skies as a valuable resource and consider it as our heritage and understand the numerous benefits that come from dark sky protection. It is our responsibility to protect and pass the environment and our cultural heritage on to the next generations.

Author Bio: Pericherla. Satyapriya is an Urban and regional planning student pursuing her final year at JNAFAU, Hyderabad. She is fascinated by the beauty of the earth as the way it was created and feels responsible for its protection, and believes it is important to appreciate, preserve and pass on our natural heritage to next generations. This article was an attempt to bring awareness about one such natural heritage – dark skies, which is diminishing due to the negligence.

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  • Association of Universities for Research in Astronomy (AURA). (n.d.). light pollution. Retrieved from Globe at Night:
  • Filmer, J. (2013, April 8). Retrieved from Futurism:
  • Insulander, A. M. (2012). Light pollution : consequences and sustainable lighting design.
  • International Darksky Association. (2019). Retrieved from International Darksky Association:
  • Light pollution. (n.d.). Retrieved from Globe at Night: