The Effects Of Light Pollution On Our Planet

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For many who have a fond appreciation for outdoor activities in the evening, light pollution has altered the sky at night and the activities of certain animals at night. The average person would not recognize the environmental problem that is now coined “light pollution.” Biologists are now exploring the fact that light pollution is making the world more dangerous for humans, animals and insects.

Light Pollution is defined as the artificial skylight (as from city lights) that interferes especially with astronomical observations. [1] When the night glare from artificial lighting increases, the visibility of the stars decreases. People that live outside the city zone or people who camp in the forests are more prone to see the beautiful stars and even other planets at night without the interruption of light pollution.

Light Pollution and the Human body

Twenty four hours of artificial light exposure can cause a series of ailments for humans. Light Pollution disrupts the circadian rhythm, affects estrogen and melatonin levels in women. Light Pollution can also affect a child's development process. The 24-hour day/night cycle known as the circadian clock, affects physiological processes in almost all organisms. These processes include brain wave patterns, hormone production and cell regulation.[2] The disruptions of the circadian clock are directly linked to a variety of medical disorder in humans. Some medical disorders due to a disrupted circadian clock are depression, insomnia, cancer and cardiovascular disease. These disruptions to the sleep-wake cycle causes sleep deprivation which certainly leads to weight gain, high blood pressure, grogginess, impaired thinking and also it can increase the risk of obtaining heart disease.

A study conducted on September 2006 by the National Institute of Environment Health Science (NIEHS) shows a dramatic increase of breast and prostate cancer, obesity, and earl stages of diabetes due to over exposure of artificial light. Studies show that the circadian rhythm controls up to fifteen percent of our genes so if the circadian rhythm is disrupted, a lot of health problems can occur.

Epidemiologic studies are now emerging suggesting that women who work at night, and who experience sleep deprivation, circadian disruptions, and exposure to light-at-night are at an increased risk of breast cancer, and possibly colorectal cancer.[3]

Disrupted circadian rhythms also affect melatonin, which is produced by the pineal gland within the brain. Melatonin helps to control the production of estrogen and it helps to regulate the body's biological clock. Sudden or continuous exposure to bright light can suppress the production of melatonin.

Melatonin levels are higher at night right before bedtime and the levels of melatonin drop when there is constant exposure to natural or artificial light. There has been numerous studies conducted, suggesting that the decrease of nocturnal melatonin levels increases the risk of a person developing cancer.

Another study that was conducted on the January 2008 issue of Chronobiology International shows that women living in neighborhoods where it was bright outside at midnight due to the artificial lighting had a seventy three percent (73%) higher risk of developing breast cancer than women who lived in areas with less or no artificial lighting outdoor.

Studies have also shown that infants who have been exposed to constant light develop a circadian rhythm much slower whereas infants who were receiving the proper light cycles fell asleep at night sooner and gained weight much more quickly.

Basically, the artificial lighting at night interrupts the natural internal clock of people. The internal clock lets us know when it is bedtime, which prepares people for rest and regaining energy. When people do not have a full wake-sleep cycle they are more prone to receiving a number of physiological ailments.

Light Pollution Impacts Animal Behavior

Animals are very sensitive to light. Many people are not aware of how artificial night lighting interferes with foraging, animal survival tactics and the threat it imposes to their existence. Night light disorientates animals that are accustomed to navigating at night with no light. For animals that hunt at night, the light may scare away their prey causing the predator to go all night with no food. Society takes for granted how much animals need darkness like humans need light.

The endangered sea turtle species face dangers with light pollution as well. Light pollution affects where the sea turtles lay their eggs. Female sea turtles will not come out of the sea to nest their eggs if the beach is engulfed in artificial light. Also, sea turtles instinctively rely on light to guide them to the sea. Due to the fact that the coastline is illuminated, the disoriented sea turtle confused causing them to move in the wrong direction confused by artificial light. The sea turtle is lured away from the ocean and moves towards the busy road which ultimately leads to death. Sea turtles die usually from exhaustion, dehydration, predation and by road kill.

Bright lights disrupt the behavior of birds especially during cloudy weather. About 200 species of birds get confused by the lights of buildings, communication towers, and other illuminated structures. Their confusion results in migration in the wrong direction, collision with artificial structures, and reduction in time spent looking for food.[4] Sidney Gauthreaux, a Clemson University biologist stated that birds are attracted to light just like moths are attracted to fire. Hundreds of yellow warblers and other types of birds have died due to becoming disoriented by artificial lighting and have crashed into illuminated structures or flown in circles until they drop from exhaustion. Some birds get confused, for instance, the nightingales' birds sing at unnatural hours in the presence of artificial light.[5] These birds are mistaking the artificial for natural day light. In England, the over exposure of light are causing birds to make nests during the fall instead of spring because their internal clocks are malfunctioning. More birds die annually from crashing into buildings than the birds that were killed during the Exxon Valdez oil spill in 1989. From 1982 to 1996, 1,500 migrating birds smacked into Chicago's McCormick Place Exposition Center.[6]

Many amphibians and certain reptiles come out in the night time to feed on algae, but when light is produced the amphibians take cover. Salamanders are amphibians known for their changing skin color which helps them to adapt in any environment. Researchers found that due to artificial light, salamanders stay hidden longer. The later they come out, the less food may be available for them to eat.

Light Pollution and the Damaging Effects on the Ecosystems

Light pollution is the major cause behind the imbalance of our ecosystem. The effects of light pollution on wildlife are now widely recognized. Lakes and coastal waterways are being affected by outdoor lighting from big buildings, lamp posts and neon store front signage. According to recently published research, dragonflies in search of water on which to lay eggs may be diverted into oil slicks, buildings, dark cars and water puddles on paved roads.[7]

The constant lighting can destroy trees, crops and wildlife. Plants and trees use sunlight for photosynthesis during the day, but at night the trees and plants need darkness to regenerate phytochrome, which is a key compound. In order for a plant to reach a proper growth cycle they depend on the two cycles, the cycle of dark and light. Darkness is critical to reproduction and the flowering process. A new study concluded that light pollution affects trees that are located to nearby street lamps. Plants measure the length of dark hours at night to determine the time to bloom and set seed. As a result of the confusion the trees drop their leaves much later than they normally would.

For water species, if natural or artificial light increases, the algal growth increases. The algae over consumes all of the oxygen in the water and will eventually lead to the death of other aquatic species. The reproductory phase of some species will be altered which will affect their natural behavior. Also, fishes are attracted to light which makes it easier for fisherman to access them more easily.

Researchers are beginning to see how light pollution affects insects and reproduction. For instance, insects are laying eggs on the hoods of cars or on the roads where eggs are less likely to hatch due to the glare of the artificial light. These insects can not tell the difference between fertile and non fertile places which ultimately affects foraging, communication and other behaviors that is critical for reproduction of insects.

Light Pollution and wasted Electricity

When light is used inefficiently, it destroys our spectacular view of the billions of star at night not to mention that thirty percent (30%) of light that projects into the night sky is wasted energy.

The effects of light pollution affect not only wildlife but humans too. Light pollution is still currently being researched but the studies are enough to prove that it affects all living organisms on our planet. If humans continue to live with light pollution, they will be more prone to developing ailments such as cancer and other physiological ailments. Society must do what they can now to help themselves as well as the wildlife especially animals that are endangered.

  1. Merriam-Webster Dictionary
  2. Chepesiuk, Ron, Missing the Dark: Health effects of Light Pollution, February, 2, 2009,
  3. Milrick DK, Davis S., Cancer Causes Control, May 17, 2006
  4. Buckley, Christine, Polarized Light Pollution Leads Animals Astray, January 7, 2009,
  5. Klinkenborg, Verlyn, Our Vanishing Night. National Geographic, November 2008.
  6. Bower, Joe, The Dark Side of Light, Audobon Magazine, March 21, 2000
  7. Smith, Dawn M., More Evidence of Light Pollution Harm to Animals, January 9, 2009