Light Pollution: Too Much of A Good Thing

Year_of_light_light_pollution_largeImages from International Year of Light 2015 – Official Trailer by International Dark-Sky Association (

A couple of years ago, we got our first call asking if we sold lights that addressed light pollution. Today, it’s a common question not only for people concerned about the issue itself, but because municipalities throughout the USA continue to add zoning restrictions about lighting to address light pollution.

Most people know certain types of light bulbs and energy sources are more eco-friendly than others. Far less have heard or understand what light pollution is and the more common problems associated with it, so here’s a brief overview with links to additional information.

What is Light Pollution?

Light pollution is far more than an obnoxious, light blaring your room while you to try to sleep. One definition of light pollution is:

“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 adverabstract lighted street at nightse health effects and wastes energy.”1

The most common forms of light pollution are:

  • Glare: Lights that are excessively and needlessly bright, and which cause visual discomfort. This includes light that disrupt sleep or relaxation, as well as an be floodlights that are blindingly bright when one walks or drives into an area. (We call this the prison break effect, where you’re suddenly surrounded by far too much bright light.)
  • Sky glow:  Brightened night skies over inhabited areas, which interferes with nature and the ability of scientists and amateurs from studying the night sky
  • Light trespass: Light that falls in areas it doesn’t need to be, such as a badly placed lights that intrude onto properties that don’t need to be lit.
  • Clutter:  Bright, confusing and excessive groupings of light which is generally the result of uncoordinated or poorly planned lighting design and implementations. (That’s why more and more local governments are imposing restrictions on how bright lights can be or how far the light can be cast, largely through building and zoning codes.1 We’ll discuss this in more detail in the second part of this post that will focus on what you can do to prevent and reduce light pollution.)

Where Have All the Stars Gone?


Here are some examples of what light pollution looks like. The picture below compares rural and metropolitan areas of Utah, and clearly shows how the night sky is “washed out” in the urban area.

Much like people in metropolitan areas globally, lots of people in Utah are missing out on lots of good old fashioned sky watching every night. For astronomers and other scientists, this means it’s harder to study the cosmos. As for animals whose instincts are significantly impacted by light, the difference between day and night, and the ability to judge seasons, it’s very damaging. And this includes negative impacts on human health.

Light Pollution: Likely to Get Worse Before It Gets Better

As the global population increases and more developing countries get access to lighting, lighting pollution is more of a problem in more parts of the world. The rapid pace of global light pollution is shown in the composite satellite images that compare night skies during 1994 and 1995 (3) to night skies in 2012(4).

composite satellite images of global light pollution, 1994 and 1995 Composite Satellite Images of Global Light Pollution, 1994-95.
Please see Sources at end of post for full attributions.

composite_satellite_image_of_Earth_night_2012Composite Satellite Images of Global Light Pollution, 2012.
Please see Sources at end of post for full attributions.

The images demonstrate that while parts of North America have less light pollution in 2012 (and other areas have more), globally the situation is getting worse. Along with the bright patches of light in the second composite image, note the large parts of Asia and Africa that show up as much lighter, indicating lower levels of light pollution.

“Traditional” Pollution and Waste of Energy

Improper lighting not only disrupts eco-systems (impacting humans and other living creatures), it’s a huge waste of energy. While it’s true that more eco-friendly forms of light (such as solar lights), most lighting still uses fossil fuel and lighting fixtures that are very inefficient.

Along with negative impacts from “carbon footprints” or increased gas, coal and oil consumption, inefficient lighting is both incredibly wasteful and expensive.The International Dark-Sky Association estimates that inefficient lighting costs the United States about $2.3 Billion per year.5

Impact on Animals and Plants

frogs and turtles are just a few animals impacted by light pollution

Turtle Photo by Manuel Heinrich Emha. CC BY-SA 2.5 (, via Wikimedia Commons

Until the Industrial Revolution, most humans woke up around daybreak and went to bed not long after sunset. In the past 250 years or so, light has dramatically changed billions of years of evolution.

Virtually all animals and plants are impacted, including humans.

Among the lifeforms that see the negative impacts from light pollution: plants, amphibians, birds, insects and mammals. Breeding, feeding, sleep and protection from predators are all impacted.

One animal that is particularly impacted by light pollution are sea turtles and toads and frogs. (That’s why many marine lights are now available in turtle-friendly amber lights that mitigate negative impacts to breeding.)

picture of migrating geeseArtificial light also interferes with birds. Along with impacting birds that feed or hunt at night, light pollution interferes with instinctual migration patterns because they can’t accurately sense the changing seasons.

Insects are negatively impacted as well, which results in a ripple effect throughout the natural food chain.

Impacts on Human Health

human skeleton with lightLast for now, but certainly not least, light pollution negatively impacts human health. In fact, the American Medical Association Council on Science and Public Health states that “Many species (including humans) need darkness to survive and thrive.” 

According to the International Dark-Sky Association (and many other sources), “exposure to exposure to artificial light at night can harm your health. Humans evolved to the rhythms of the natural light-dark cycle of day and night. The spread of artificial lighting means most of us no longer experience truly dark nights…

Research suggests that artificial light at night can negatively affect human health —increasing risks for obesity, depression, sleep disorders, diabetes, breast cancer and more.”

Like most animals, our biological clock or circadian rhythm can be disrupted by artificial or excessive light at night because our bodies’ ability to produce melatonin is impaired. Sleep disruptions or sleep disorders are the first things we notice, but other impacts of reduced naturally produced melatonin is impairments to the immune systems, increased depression and even higher rates of diabetes and cancer.

Melatonin also has antioxidant properties, and helps to lower cholesterol and aid in the proper function of the thyroid, pancreas, ovaries, testes, and adrenal glands.

Want Proof?
In 2012, the British Medical Journal published  a study pooling 34 previous studies and a study of 2 million other participants across the industrialized world. The results: people who work night shifts (also called third shift or graveyard shift) have a 23% higher risk of heart attacks, and increased rates of breast cancer, diabetes and strokes.7

What Can You Do About It?

We hope that you’ve found this article interesting and that you check out the links throughout it for more information.

While you may not be able to control everything, you have a lot more power than you think. That’s why the next article related to the International Year of Light and Light-based Technologies will provide concrete examples of what you can do to reduce light pollution from your property. We’ll also discuss ways you can have a positive impact at your local, state and federal government levels, as well as worldwide.

That post also will include links to interactive features where you can help monitor light pollution, educational materials for use in classrooms or public presentations, and more things to help you learn about, and help reduce, light pollution.

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All Rights Reserved.



2. Photos courtesy of Jeremey Stanley via Originally posted to Flickr as “Southern sky, country vs. city

3., Data courtesy Marc Imhoff of NASA GSFC and Christopher Elvidge of NOAA NGDC.  Image by Craig Mayhew and Robert Simmon, NASA GSFC. (from Wikipedia.
(Public public domain: contains materials that originally came from the
U.S. National Oceanic and Atmospheric Administration, taken or made as part of an employee’s official duties.

4., originally posted to (Public public domain: contains materials that originally came from the U.S. National Oceanic and Atmospheric Administration, taken or made as part of an employee’s official duties.)

5. International Dark-Sky Organization (

6. International Dark-Sky Organization (

7. Time Magazine, “It’s Called the Graveyard Shift for a Reason.”