Are Bright Lights at Night Hazardous to Your Health?
Nighttime lighting, especially LED, not only obscures stargazing, there's research that links it to illness in humans
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Look at the stars! look, look up at the skies
O look at all the fire-folk sitting in the air
The bright boroughs, the circle-citadels there!
Down in dim woods the diamond delves! the elves' eyes
-- The Starlight Night, by Gerard Manley Hopkins
Photo credit: Getty Images
This week, I'm in western Montana, near the majestic mountain range of Glacier National Park, far from any city lights. On Sunday night, the moon was in a waxing crescent phase (I only knew this because I Googled it), close to ideal conditions for stargazing because the moon is very dim. It was a sunny, clear late summer day and the sky remained that way as night fell. Just before midnight, I went outside and looked up. The enormous black canvas of night was sprinkled with the pinpricks of many stars. It was beautiful.
Last May, I wrote about the fun and joy of stargazing, where the best places for spotting stars, constellations, galaxies and planets are located (according to the International Dark Sky Association, or IDA), and how light pollution is making it harder for people around the world to see them. The IDA says "light pollution" is expanding at a rate of 2 percent a year on average, affecting almost every region of our planet.
In late April, I drove to Cherry Springs State Park in Pennsylvania, one of the IDA's recommended dark sky locations, to see for myself the wonders above. It was dazzling even with a bright full moon washing out the sky when it rose. Until then, I hadn't even noticed that I never see anything like that in New York City where I live. I didn't even realize what I was missing.
This summer, the IDA released a new report, Artificial Light at Night: State of the Science 2022, an updated assessment about light pollution and its effects. The findings were alarming. Not only are stars getting harder to see because of artificial light at night (ALAN), there is a growing body of medical research that suggests that nocturnal illumination is harmful to our health.
"Light pollution is surging in both its presence and reach across our planet," the report says. "It is the source of both known and suspected harm to the nighttime environment."
Photo credit: Getty Images
Light pollution causes something called skyglow, which is the brightening of the night sky in and around urban areas where there is brilliant outdoor illumination, much of it for no good reason.
"(Researchers) found that skyglow fouls the night sky for more than 80 percent of all people and more than 99 percent of the U.S. and European populations," the report said.
In recent years, LED lights have become a growing source of ALAN around the globe because of their energy efficiency. Solid state lighting, which includes LED lights, now accounts for almost half of global lighting sales, according to the IDA. LED lights are cheap and give off more short wave-length light. But it emits much more light -- in lumens, a measurement of the amount of light -- that humans are sensitive to. Brighter lights, more light pollution.
The report says that poses a threat to humans and animals.
"ALAN exposure impacts almost every species studied by scientists," the report said.
Artificial nocturnal light can disturb animals' circadian rhythms, change the interactions between predators and prey, and alter the competition for resources by species by affecting their attraction to habitats, according to the report. In Toronto, tens of thousands of birds reportedly die each year from slamming into buildings after becoming disoriented by nighttime lighting.
The prospective effect on people is especially concerning. The IDA report said there is a "scientific connection" between ALAN exposure and "adverse human health consequences." There's evidence that ALAN exposure delays or prevents the release of the hormone melatonin at night which helps us sleep. That is not good.
A 2019 National Geographic article similarly reported: "Whether it's a computer screen, bright bathroom light, or intense street lights shining in our windows, indoor and outdoor electric lights interfere with those circadian rhythms by stunting the ebb and flow of (the hormone) melatonin. Obesity is one consequence of light messing with our nighttime physiology. Based on a number of studies, low melatonin levels and circadian disruption are also thought to play a role in heart disease, diabetes, depression and cancer."
Photo credit: Getty Images
I found a number of recent medical studies that agree.* One was a study in Spain in which the researchers concluded, "both prostate and breast cancer were associated with high-estimated exposure to outdoor ALAN in the blue-enriched light spectrum (i.e., the kind of light from LEDs)."
In 2016, the American Medical Association, citing potential harmful effects on humans and the environment, called on cities to restrain the use of LED outdoor street lighting.
"Brighter residential (LED) lighting is associated with reduced sleep times, dissatisfaction with sleep quality, excessive sleepiness, impaired daytime functioning and obesity," the AMA resolution stated.
It's not just the stargazing at night that's affected by the growing use of artificial outdoor lighting. It could also threaten our health and well-being, according to a growing body of scientific research. As is often the case -- think about carbon emissions and the climate change occurring now -- there can be a price to pay for progress.
Photo credit: Getty Images
* Among the studies was one published in the Journal of the American Medical Association Internal Medicine that looked at more than 43,000 women and found that exposure to ALAN was "significantly positively associated" with obesity. Other studies found a potential link between LED lights and both obesity and breast cancer.
Cover photo credit: Getty Images