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Holiday lighting often increases light pollution, but there are ways to minimize it
Experts say purchasing lights with a timer can reduce light pollution, cut down on ‘blue light’
Dec. 24, 2024 5:30 am, Updated: Dec. 26, 2024 9:39 am
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With homes, parks and businesses decked in holiday lighting, the glow from those lights can cause light pollution and harm humans’ and animals’ sleep schedules. Experts say there are some simple steps people can take to reduce their impact on the environment and neighbors.
Light pollution happens when the night sky is brightened by human-made lighting, which can disrupt visibility of the dark sky. With a lighter night sky, nocturnal animals’ biorhythms can be disrupted and astronomers’ studies can be skewed.
It also can have adverse impacts on human sleep and health.
Jun Wang, chair of the University of Iowa’s Department of Chemical and Biochemical Engineering and a James E. Ashton professor in the College of Engineering, said one of the best ways people can reduce their contribution to light pollution while staying festive is by purchasing holiday lights that can be controlled with a timer.
“With a timer, you could set the lights to run from sunset to 10 or 11 p.m., then you turn it off,” Wang said.
By turning the lights off before going to bed, people are able to enjoy the lights, without “blue light” seeping into bedrooms at night, Wang said.
Blue light is a part of the visible light spectrum with short wavelength and high energy. Blue light is emitted from the sun, but also artificially from electronics.
The blue light from electrics — like smartphones, televisions and computers — can affect humans’ sleep cycle.
“Turning off the lights before bed will help sleep and also save energy,” Wang.
Jenny Ziegler Baker, a professor of civil construction and environmental engineering at Iowa State University, also said that light timers should “dim or turn off” holiday lighting when they are not being viewed.
Wang said the physical effects of light pollution could be harmful to everyone.
“A lot of pollution could have a huge risk to our health, and there are a lot of clinical studies to show that,” Wang said. “With more new technology, there will be more and more blue light, and that blue light really hurts our body clock.”
To emit less blue light, Ziegler Baker recommends selecting holiday lights in warmer colors, like warm-white, red and amber, which can help reduce the effects of light pollution.
When to use exterior lighting
Ziegler Baker said when homeowners or businesses are considering putting up outdoor lights — either for the holidays or otherwise — they should consider a few different concepts.
Ziegler Baker said the Illuminating Engineering Society of North America has principles for responsible outdoor lighting.
IES’s Five Principles include:
- Useful: Use light only if it is needed
- Targeted: Direct light so it falls only where it is needed
- Low Level: Light should be no brighter than necessary
- Controlled: Use light only when it is needed
- Warm-Colored: Use warmer colored lights where possible
“The ‘useful’ and ‘targeted’ principles are difficult to apply for holiday lights because the lights are decorative, not so much task-based,” Ziegler Baker said. “That being said, the ‘low-level,’ ‘controlled’ and ‘warm-colored’ are all principles of responsible outdoor lighting that can be applied to holiday lights.”
Ziegler Baker recommends that holiday lighting incorporate lower-lumen output lights. Lumens are the unit of measurement for the light emitted and perceived by the human eye.
“Holiday lights do not need to be overly bright to give a nice glow and/or twinkle effect,” Ziegler Baker said. “With regard to brightness, it is also a good idea to keep in mind the surfaces around holiday lights. Some surfaces may reflect more light into the night sky or become more glary than intended.”
Asked why more people don’t use environmentally-friendly holiday lighting, Ziegler Baker said it usually is not about money — the cost is not vastly different — but rather not knowing other options.
“I think a big piece of it may likely be that they just are not thinking about light pollution or possible harmful effects from their holiday decorations,” Ziegler Baker said.
Olivia Cohen covers energy and environment for The Gazette and is a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.
Comments: olivia.cohen@thegazette.com
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