Shining Some Light on the Vanishing Night

Happy International Dark Sky Week! 

For evolutionary reasons, most of us humans are inherently fearful of the dark, and we now have an easy solution literally at our fingertips: turn on the lights

Today, we are bathed in ever-increasing amounts of artificial light. So much so that 80% of North Americans cannot see the Milky Way.

With increased amounts of artificial light in our lives, many of us have forgotten (or perhaps never known) about the importance of darkness.

To be clear: We need light!

Light is the engine for nearly all natural systems on earth.

• Light energy from the sun is first captured by plants and, through the process of photosynthesis, is converted to food. That energy is moved up the food chain to animals that eat plants, then animals that eat those animals, and so on.
• Energy from the sun fuels the water cycle.
• Sunlight is responsible for hormone regulation in our bodies, particularly of the hormone melatonin, which makes you drowsy and tired as the light dims in the evening. Light, received by photoreceptors in the eye, inhibits the production of melatonin during the day, helping you feel alert, happy, and productive.
• Sunlight is responsible for the production of Vitamin D in our skin, which is required for bone growth and other important functions in the body.

But...We need darkness, too.

All living things have evolved over eons with regular periods of light and dark.

• Light/dark cycles trigger biological cues for animals and plants. Feeding, breeding, flowering, and hibernating are all driven by these light-sensitive rhythms.
• Regular periods of light and dark produce circadian rhythms necessary for normal sleep-awake cycles, and these cycles are encoded in our DNA.

Artificial Light & Light Pollution

Since the electric light switch was flipped in 1879, artificial light has made our city streets safer; allowed for more industrial production; provided us with entertainment through film, television, and our now our personal digital devices; and extended our daytime activities into the night.

We love artificial light, but there is a dark side to all this light.

You are probably familiar with water, air, and land pollution, but did you know that light can also be a pollutant?

Light pollution is the inappropriate or excessive use of artificial light, and it’s a growing problem:

1. Artificial light wastes energy and money.

Too much light or light that shines where it is not needed wastes energy—more than $3 million is wasted every year in the US from excessive outdoor lighting alone!

2. It threatens wildlife.

Insects are an essential part of the food web. Sixty percent of insects are nocturnal, and many of those are attracted to light. When insects get pulled into the light, they are not feeding or mating. Most end up dying of exhaustion or getting eaten by predators.

Most birds migrate at night using the moon and stars to navigate. Bright lights confuse them, causing them to fly around buildings until they drop from exhaustion or fly into buildings and die from window strikes. The photo below, courtesy of FLAP, shows dead birds collected over the course of a year after hitting lit windows in Toronto.

Newly hatched sea turtles use the moon to guide them to the safety of the sea. Artificial lights draw them inland, where they die of dehydration or predation.

3. It disrupts the seasonal rhythms of plants.

Artificial light can cause plants to flower earlier in the season, disrupting their relationship with pollinators which results in lower fruit and seed production.

Naturally dwindling light at the end of the growing season triggers plants to prepare for winter. Artificial light may interrupt vital functions necessary for plants to survive the cold season.

4. Artificial light impacts human health, too.

Exposure to artificial light beyond a natural day cycle throws off our circadian rhythm, which can have health-related consequences, including sleep disorders, anxiety, obesity, depression, diabetes, cancer, and more.

We should also consider the impact on our psychological health when we can’t escape city lights and experience a naturally dark sky. Being able to connect with the night sky can be meditative—it helps us better understand our place in the universe.

So, what can we do?

By making small changes in our day-to-day routines, we can help bring back the beneficial night and reap the benefits of darkness:

• Use light only where it’s needed and turn lights off when not in use.
• Use dim light in the evening/at night.
• Sleep in the dark and get natural light early in the day, every day.
• Limit screen time and turn down the brightness level on digital devices in the evening/at night.
• Use shielded lights outside to prevent light from extending beyond its intended purpose.
• Use motion detectors.
• Join us for a night hike at one of our parks, our upcoming Night Hike at Hitchcock Nature Center on April 17th, or our annual Perseids Night Sky event on August 14th!
• Enjoy naturally lit night skies at one of Pottawattamie County's habitat areas: Farm Creek Public Wildlife Area or Wheeler Grove Conservation Area.

Read more: How Artificial Light Affects Us

Read more: Wildlife & the Night