People often ignore light pollution unless they’re in a bright city and want to watch some astrological event, such as a meteor shower, but it has a larger effect than that. Most animals are affected by light levels, and light during the night distorts many natural processes in the animals around us. Migration, reproduction, and activity levels of many species are determined by ambient light levels.

Humans also need darkness to produce melatonin, a hormone that regulates our sleep cycle, reproduction, and our immune system. Its effect on our health is not fully understood.

How Light Pollution Effects The Environment

Disruption Of Nocturnal Animals

Nocturnal (active at night) and crepuscular (active at twilight) animals and birds are naturally active during twilight and in the dark. Consequently, a well-lit night prevents them from operating at their optimum. This can affect their breeding, food gathering, and sleep patterns. Our light pollution disrupts their environment, as well as our own.

Affects Turtle Hatchlings

Sea turtle hatchlings find their way to the sea by moving away from darker land areas and toward the brighter moonlit ocean. Artificial light confuses this mechanism, leading them onto land, away from the ocean.

Turtles lay their eggs in dark stretches of beach, away from lights. Light pollution reduces the number of laying sites, crowding the remaining dark beaches, where predators that find them have more impact on their population.

Nocturnal Frogs Suffer

Artificial light severely restricts the ability of nocturnal frogs to see their prey. This makes it difficult for them to feed themselves. This is thought to be because their eyes don’t adjust to changing light levels quickly. It sometimes takes their eyes over an hour to adjust after exposure to artificial light.

Prey Species Can Be More Vulnerable

Sockeye Salmon fry’s behavior is determined by light levels. Any light more than 0.1 lux prompts them to stop swimming downstream and seek shelter in the shallows, where they fall prey to cottids near the shore. This is thought to be part of the reason that the species is in decline in the Cedar river in the state of Washington. It is exposed to both direct night lighting and sky glow.

Light Attracts And Confuses Birds

The light pollution from lighthouses and well-lit skyscrapers attract birds that become disoriented and collide with each other or buildings mid-flight.

The Long Point lighthouse on Lake Erie in Ontario saw high mortality rates until it switched from a high-intensity rotating light to a lower-intensity blinking light in 1989. The change greatly reduced the deaths from collision.

The Night Sky

The most obvious effect is our night sky. Millions of people now live where they cannot even see the Milky Way on a clear night. Many of us have to do without one of the most beautiful vistas that exist.

Ways That We Can Reduce Light Pollution

Motion Detectors

Instead of leaving yard or entry lights on all night, use motion detectors to turn them on when they are actually useful. This not only reduces light pollution, it saves energy. A light that is on when it’s not being used is wasteful.

Use Dimmers Whenever Possible

We often don’t need as much light as we have available. Our eyes adjust to light levels. As a result, we can usually navigate through a yard or room just fine in low-light conditions. This will help to reduce the light pollution that we would otherwise need to adapt to.

Lower Your Lumens

There is no need for a 100 Watt light bulb that puts out 1500 lumens if we could see fine with a 60 Watt, 900-lumen bulb. If you find yourself straining to see because there is just not enough light, it’s easy enough to change to a brighter bulb. We can reduce light pollution by trying to err on the side of not enough light, instead of too much light.

Campaign For Dimmer Street Lights

Many cities and towns have needlessly bright streetlights. People aren’t usually trying to read fine print or do delicate surgery outdoors at night. The vast majority of them are simply traveling from one place to another or looking at the night sky. The latter is an activity that light pollution actively interferes with.

Timers To Control Lighting

We want well-lit parking lots while the shopping mall is open for business, and for the period that people are leaving after it closes. Nobody needs that lot to be brightly lit at 3:00 AM. Most of the lights can be turned off an hour after closing, leaving just a few on to prevent total darkness. If every business did this, we’d have much less light pollution.

Task Lighting

We don’t need to light the whole room to read a book, lighting the book is enough. When we’re watching TV or a movie, a brightly lit room prevents us from seeing the screen well. A dim light behind the screen gives us a better experience. Light just where we use it gives us less interior light pollution than the ceiling fixtures do.

Shielded Lighting

The image on FAU Astronomical Observatory’s website shows that shielded lighting fixtures are perfectly effective at producing all of the visibility that we need without shining into the sky. We can reach our visibility goals without producing unnecessary light pollution.

It doesn’t need to be an expensive or disruptive project, either. If we switch to shielded bulbs whenever we replace a bulb, it wouldn’t be many years before we would greatly reduce our light pollution.

It takes tremendous ignorance to assume that the rest of nature will easily adapt to the environmental change our night lighting has caused. Only monumental arrogance would allow us to think that these problems are unimportant.

We know how to solve or mitigate much of this light pollution. What do you intend to do to help solve it?

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