Have you ever thought about how wonderful it is that you can see the stars in the night sky? It’s easy for us to take this miracle for granted, but visitors from cities and suburbs notice it right away. The night sky is a precious gift.
For ancient man, the night sky was fascinating entertainment; a companion, the equivalent of today’s wide screen TV. The ever-changing constellations and phases of the moon marked the passing of time, and provided a dependable way to navigate. In today’s 24-hour world, many people have lost touch with the infinite wonder of the night sky, but we in rural southwest Ohio can still enjoy it.
Like so many things in the natural world, darkness at night is a non-renewable resource like clean air, clean water, peace and quiet. Little by little, we can lose these precious things without even realizing it. Once they’re lost it’s very hard, almost impossible, to get them back.
For all of earth’s history, life has relied on a predictable rhythm of day and night. It’s encoded in the DNA of all plants and animals. Plants and animals depend on Earth’s daily cycle of light and dark rhythm to guide life-sustaining behaviors such as reproduction, nourishment, sleep and protection from predators.
Humans have radically disrupted this cycle with 24 hour lighting. Night lighting is a mixed blessing. Scientific evidence suggests that artificial light at night has negative, and sometimes deadly, effects on many creatures including amphibians, birds, mammals, insects and plants. According to research scientist Christopher Kyba, for nocturnal animals, “the introduction of artificial light probably represents the most drastic change human beings have made to their environment. Near cities, cloudy skies are now hundreds, or even thousands of times brighter than they were 200 years ago. We are only beginning to learn what a drastic effect this has had on nocturnal ecology.”
Humans have also evolved to the rhythms of the natural light-dark cycle of day and night. Like most life on Earth, humans live by a circadian rhythm (our biological clock), a sleep-wake pattern governed by the day-night cycle. Artificial light at night can disrupt that cycle. The spread of artificial lighting means most of us no longer experience truly dark nights.
Research suggests that artificial light at night negatively affects human health, increasing risks for obesity, depression, sleep disorders, diabetes, breast cancer and more. Our bodies produce the hormone melatonin in response to circadian rhythm. Melatonin has antioxidant properties, induces sleep, boosts the immune system, lowers cholesterol, and helps the functioning of the thyroid, pancreas, ovaries, testes and adrenal glands. Nighttime exposure to artificial light suppresses melatonin production. It’s also bad for your eyes. According to a 2012 report from the American Medical Association, “Glare from nighttime lighting can create hazards ranging from discomfort to frank visual disability.”
Unfortunately our own night skies are dramatically brighter than they were just a few short years ago. Billboard lighting and 24-hour lighting by residents and businesses threatens to blot out our view of the heavens. Most people never think about light scatter or the negative impacts of artificial light at night. We need to better appreciate what a priceless, non-renewable resource it is, to see the stars in the night sky.
See next week’s “Let’s Grow” column for some practical suggestions on how to reduce the wasted light that’s stealing our skies each night.