Night shift work has been consistently associated with higher risk for cardiovascular disease, cancer, insomnia, depression and irritable bowel syndrome. Exposure to light at night is not only leaving scars on people’s well being but is affecting wildlife and entire ecosystems, it wastes energy, money and gives astronomers headaches.
For billions of years, all life has relied on the Earth’s predictable rhythm of day and night. Circadian rhythm that all plants and animals developed, is encoded in their DNA. Nighttime exposure to artificial light has been shown to suppresses melatonin production, a hormone with antioxidant properties that induces sleep, boosts the immune system, lowers cholesterol, and helps the thyroid, pancreas, ovaries, testes and adrenal glands to function properly.
If our biological clock which regulates the cell cycle is disrupted, the body is pushed out of balance and our health can become compromised. A new study recently published in the journal Environmental Health Perspectives shows women who are regularly exposed to outdoor light at night have an increased chance of developing breast cancer. For years, researchers have noted similar results. One study even suggested that working night shifts for 30 years or more doubles the risk of developing breast cancer.
“Disruption of circadian patterns could be associated with abnormal cell divisions that occur in cancer. Indeed, animal studies have shown that mice subjected to an inverted light cycle experience higher levels of mammary tumors.” said lead author Peter James, an assistant professor at Harvard Medical School’s Department of Population Medicine for Seeker.
Researchers linked data from satellite images of Earth taken at night to the residential address of each study participant. They considered the influence of night shift work and a large number of other health and socioeconomic factors. They concluded that exposure to light at night may increase breast cancer risk by up to 14 percent. The study looked at data from almost 110,000 women who enrolled in the Nurses’ Health Study II. That´s not to say men are not in danger as well. Studies suggest that night shift work and exposure to light at night could be linked to several other types of cancer, including prostate cancer.
By now conditions like diabetes, insomnia, depression, irritable bowel syndrome, heart disease, and obesity were linked to light exposure at night. Even those who do not work the night shift often watch television, stare at cell phones, laptops, and other artificially lit devices in the evenings. Street lamps, neon business signs and other lighting sources engulf our homes in artificial light and cause enormous negative effects on wildlife. Artificial lights also turn nocturnal pollinators off. Sea turtles hatch from their eggs on the beach at night and instead of going towards the sea, the brighter sky glow sways them toward the cities. Fireflies, symbols of the night, are losing populations across the globe. Migratory animals are unable to navigate by moonlight or stars and the list goes on.
What Can We Do Today
Some artificial lights are more harmful than others, depending on their color temperature. Exposure to blue light at night is particularly undesirable. Most LEDs used for outdoor lighting as well as computer screens, TVs, and other electronic displays, produce abundant blue light. By using software tools available on the internet we can change the light intensity and color temperature shown on display screens, or invert colors for white letters on a black background. You might also consider switching your house lighting to warmer colors: warm white, yellow, amber.
Street lights are responsible for the most of the light pollution on Earth. The glare is scattered by the atmosphere, creating sky glows over the landscape. You can search your neighborhood on the light pollution map and get familiar with your personal situation. By shutting your blinds, the light will stay trapped inside where you are actually using it. You might consider replacing your outdoor lights with motion sensor lights or putting a shield over the bulbs to limit waste. Sometimes street lights are poorly designed and end up shining rays into your home (known as light trespass). You can learn how to make a difference and take action.
It is vital that more research is carried out on the topic, especially because light pollution already covers nearly 80% of the globe and has intensified in the past half-century, increasing by about 6% each year in North America and Europe. It is not too late to stop the devastating effects it causes, but we will have to work together.
Learn more about effects of artificial light pollution in the excellent video below:
To better understand blue light watch video below:
By Andreja Gregoric, MSc