Holidays & Light Pollution

The holiday season appears to only worsen the already damaging effects of light pollution.

With the holiday season behind us, many of us have taken down and packed up our house decorations. However, what we may not realize when we begin to unpack next year is that our seemingly harmless annual traditions actually have severely negative ecological impacts.

The damaging effects of light pollution is an issue that is often overlooked in today’s media. More publicity has been given to global issues such as climate change and rising sea levels. However, the dangers that light pollution presents to us at a localized level should not be disregarded.

In 2014, NASA published a report that measured the light intensity of 70 cities between Black Friday and New Year’s Day. They found that the light intensity produced by urban areas increased by 20 to 30 percent, and by 30 to 50 percent in suburban areas. This can have a direct impact on the lives of animals who live in nearby areas, such as rodents in a park, insects in your front lawn, or birds flying overhead.

Exposure to light in the day affects levels of melatonin, which is a hormone that is responsible for regulating body functions on a light-based schedule within an animal. In humans, melatonin helps our bodies go to sleep at night. When exposed to light, our bodies suppress production of the hormone in our brains in order to wake us up. It can be found in most animal species whose lives are affected by exposure to light, which includes almost all of them.

Because many animals rely on melatonin to get restful sleep, a 20 to 50 percent increase in light intensity during the holiday season means that their bodily schedules are affected by all of the lights that we’re putting up. It’s a well-known fact that sleep deprivation causes damaging effects to the cognitive ability of humans. Parallels can be drawn to other members of the animal kingdom as well.

According to the US National Library of Medicine, a 1989 study on laboratory rats observed that when deprived of sleep, they exhibited weight loss despite an increase of food intake, more aggressive behavior, and a slowed startle response. It should be noted that the rats in this experiment were completely deprived of sleep rather than only being partially affected as the animals exposed to holiday lights would be. Even so, it can be inferred that these attributes would still be found in the latter group to a lesser extent.

Sleep deprivation can have a profound effect on an ecosystem. Animals that suffer from weight loss contain fewer nutrients for their predators, which may force carnivorous or omnivorous animals to eat more to try to compensate. In turn, this causes the prey’s population to dwindle. Slowed startle responses in prey can also lead to a decline in their species’ population, and increased aggressiveness in animals can cause social problems in their communities.

In 1991, a paper published by two scientists in Tucson, Arizona, Dr. Tim Hunter and David Crawford, observed that approximately 30 percent of nighttime outdoor lighting makes it into the night sky. This has a severe impact on birds, especially those who migrate at night.

Birds who migrate at night rely on the light produced by the moon and stars to guide them to their destination. Artificial light tampers with these instincts, as it often draws the birds off their course. This is especially harmful in cities, as it will cause the birds to become lost in the maze of bright lights that are produced by heavily urbanized areas.

There is an obvious negative effect that light pollution has on ecosystems and the wildlife that exists within them. With the holiday season, the intensity of light pollution only increases.

How does one help to solve this problem? Ideally, there would be a public outcry against bigger causes of light pollution, such as street lamps and tall buildings. But until that happens, the simplest thing that one can do is to not put up any Christmas or Hanukkah lights.

And what of the holiday magic? What of the seasonal joy and soul-stirring spirit that comes with setting up festive decorations? It could be argued that the cultural significance of holiday lights outweighs any ecological impacts that it may have on our environment. This is a valid point, as cultural traditions play a large role in how we organize ourselves as a society. However, we must all remember that unless we care for the other species with whom we share our space, there won’t be any environment left to play host to our festivities.