Dark Sky preservation aims to curb light pollution so we can enjoy the beauty of the night sky, protect our health, and protect wildlife. It is just as important as tackling air and water pollution. Without quality water, air, and darkness at night, our health and well-being are diminished.

Some people have the idea that the only negative side effect of light pollution is the inability to see the stars. They are unaware of the harmful effects it can have on all life on earth.

I started Night Sky Tourist to introduce people to some of the best Dark Skies on earth for skywatching, to illuminate ancient astronomical sites around the world, and to bring attention to the need for Darky Sky advocacy.

Consider the following four reasons why Dark Sky preservation is so vital in protecting life on earth:



The human body and physiology closely follow the rhythms of the natural cycle of bright days and dark nights. Before the invention of artificial light, people spent their evenings in relative darkness. The brightest thing they had at night many thousands of years ago was a small fire and later came oil lamps and candles.

Like all life on our planet, humans adhere to a circadian rhythm, an internal master clock that is vital for our overall health.

This rhythm interacts with all the systems of our bodies, affecting our hormone levels throughout the day and night, and even modifying our genetic code. When we follow nature’s cue with natural cycles of light and dark, we keep our master clock tuned with Earth’s 24-hour cycle and protect our long-term health.


Circadian disruptions happen when our master clock gets out of sync with the natural day and night cycle. This disruption can put us at risk for physiological and behavioral struggles. People who work at night or who do shift work perpetually struggle with circadian disruption because the internal master clock is at odds with the artificial light needed to do their jobs.


We should take this disruption seriously because of the profound effects it has on our overall health. Studies have shown that it can increase our risk of obesity, diabetes, mood disorders, reproductive problems, and cancers.

Numerous studies spotlight the link between working night shifts and exposure to light at night to increased risks for breast and prostate cancers, along with many other health problems. 

This disruption can also affect our natural sleep patterns. Quality sleep at night helps reduce weight gain, stress, depression, and the onset of diabetes.


Studies show that exposure to light at night, even if it’s dim, can suppress the body’s ability to produce melatonin. This hormone is responsible for regulating our sleep-wake cycle, metabolism, and immune system.


When light shines directly into our eyes, it’s called glare. Overly bright and poorly shielded outdoor lighting creates glare that can produce a blinding effect. As we age, our susceptibility to temporary blindness from light glare increases. Blue light, like many of the newer LED streetlights and car headlights, is more likely to impair our vision.


Our nighttime environment has radically changed in less than 100 years, putting our health at risk. When we stay up late to watch a movie or lay in bed scrolling through our smartphones, our eyes are filled with artificial blue light. 

Research shows that screen time in the evening stimulates the brain, causes eye strain and retinal damage and creates melatonin disruption. In a study of people who read ebooks before bed, screen readers reported they were more alert before bed, took longer to fall asleep and achieve the restorative REM state, and were more tired the next morning.


We can protect our natural internal clock and melatonin production by staying close to nature’s cycles as much as possible. 

  • Dim indoor lights as it gets darker. Install dimmer switches and continue to dim a little more every 20-30 minutes until bedtime. 
  • Use light bulbs with a warm color temperature under 3000K. 
  • If you must use an electronic device, set it to night shift or use an app that darkens the screen with an amber hue to reduce the blue light. 
  • If artificial light enters your bedroom windows, use blackout curtains. Cover or remove light sources such as clock radios and charging stations.
  • If a nightlight is necessary, use a less disruptive red light.


Plants and animals depend on Earth’s natural cycles of bright days and dark nights to govern their life-sustaining behaviors. Reproduction, nourishment, sleep, and protection from predators are all affected by artificial light. Scientific evidence suggests negative and deadly effects on amphibians, birds, mammals, invertebrates, our pollinators, and plants.


The Great Barrier Reef near Australia contains more than 130 different species of coral that depend on moonlight for spawning. Bright urban lights spread light pollution far enough to mask the moon’s phases, throwing the coral’s biological clock out of sync. This contributes to the rapid death of coral.


Wetland habitats are home to amphibians such as frogs and toads. Their nighttime croaking is part of their breeding ritual. Artificial lights interfere with reproduction by disrupting this nocturnal activity leading to a reduction in their population.


Although sea turtles spend their lives in the waters of the ocean, they hatch on land. The eggs are buried in the sand along beaches. They hatch at night and find their way to the sea by detecting the bright horizon of moon and starlight over the ocean. However, artificial lights lure them away from the ocean, causing a state of confusion about which way to run. In Florida alone, millions of hatchlings die this way every year, contributing to a dramatically reduced number of sea turtles.


Many birds migrate and hunt at night, using moonlight and starlight to navigate. Artificial lights cause confusion, luring them to wander off course toward dangerous nighttime landscapes of city lights. Every year, millions of birds die by colliding with illuminated buildings and towers.


Research has shown that light pollution dramatically reduces the activity of nocturnal pollinators. Although researchers are not sure why, they have found that this impacts the daytime pollinators. We are experiencing a rapid decline worldwide of bees and other daytime pollinators, and light pollution is contributing to the problem. 


The negative effects of artificial light at night is just now being understood. Every year, new research adds more species to the list of animals impacted by light pollution. The dung beetle, for example, uses the Milky Way to navigate. Other impacted animals include hummingbirds, wallabies, zebrafish, Monarch butterflies, Atlantic salmon, songbirds, bats, owls, insects, geckos, fireflies, and more.


We can all do our part to protect the habitats directly influenced by our own homes. 

  • Use only fully-shielded fixtures for all outdoor lighting so light shines down, not up.
  • Use only the amount of light needed. Too much as wasteful and harms wildlife. Turn off lights in office buildings and homes when not in use.
  • Security lighting can be set up with motion sensors and should be shielded.
  • Warmer color temperature lighting of 3000K or below to reduce the blue (cool) color light reduces the harmful impact on animals and plants.


Although it may seem contradictory, a brightly lit nighttime environment does not necessarily improve safety or security. Studies have found no clear evidence that increased outdoor lighting deters crime or increases safety.


It is important to all of us to keep ourselves and our property safe from theft and vandalism. Yet badly designed outdoor lighting can actually reduce our safety. Bright and poorly aimed lights can hide danger by creating deep shadows where criminals can hide.

Crimes like vandalism and graffiti thrive on night lighting. For example, bright dusk-to-dawn outdoor lights allow criminals to quickly see the contents of parked cars.


Lighting in parking lots, shopping areas, parks, and other public places can improve safety, but only if done right. Improperly aimed and poorly shielded lights actually attract criminals by allowing them to see what they’re doing. Bright dusk-to-dawn lights tend to increase instances of property damage. 

The city of Chicago conducted a study that found a correlation between increased crime and brightly lit alleyways. 


Motorists and pedestrians can be temporarily blinded by glare from unshielded streetlights and electronic signs. This contributes to tragic traffic and pedestrian accidents at night. Older individuals have an increased risk for this kind of temporary blindness.

A 2015 study published in the Journal of Epidemiology and Community Health found that streetlights don’t prevent accidents or crime, but do cost a lot of money.

Glare from street lights diminish the eyes’ ability to adapt to low-light conditions, making driving under them less safe.


  • Use fully-shielded fixtures to make the light shine down, not up or outward which creates glare.
  • Only use lights where needed, installing timers and dimmers. Turn lights off when not in use, or install a motion sensor.


No one is suggesting that there should be no lights. Real security depends on the wise use of lighting. The goal should be visibility. Instead of more and brighter lights, we need smart lighting. The most useful lights at night direct light downward to the exact areas that need to be lit without allowing glare to enter the eye. It is possible to protect the natural nighttime environment without compromising safety.


Excess lighting pumps millions of tons of carbon into our atmosphere each year and causes light pollution. Light pollution increases greenhouse gas emissions, contributes to climate change, and increases our energy dependence.


Each year, the U.S. emits about 15 million tons of CO2 to power residential lighting. That’s the equivalent of emissions from 3 million passenger cars. To offset all that carbon dioxide, we would have to plant about 600 million trees every year.


Bad lighting results in a loss of about $3 million per year of energy. About 35% of light is wasted by unshielded and poorly-aimed outdoor lighting. 


Imagine how much energy you would use and pay for if you ran the dishwasher one extra time every single day, or 30 times a month. That’s how much energy and money the average house wastes with poorly designed outdoor lighting.


Cut energy use by 60-70% and reduce carbon emissions with proper outdoor lighting. This includes using fully-shielded fixtures that are aimed at the exact spots you need to illuminate, reducing the color temperature, and reducing the brightness of the bulbs. Turn off indoor and outdoor lights when not in use.

Be aware that fully-shielded fixtures can provide the same level of illumination as unshielded fixtures that aren’t as bright, but with lower cost and less energy waste.


Remember, Dark Sky friendly lighting does not mean “no light”. It means using the light that you need for a specific task in the most efficient manner possible.

For more information about Dark Sky friendly lighting and fixtures, visit the International Dark Sky Association website at https://www.darksky.org.