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Christmas lights are a staple during the holiday season, with the sparkling strings wrapped around trees, homes, and streets.

But the eye-catching displays do have an environmental cost.

Many major cities showcase their brightest lights during the winter months. In London, England, for example — a city known for its holiday decor — 750,000 LED light bulbs are used. And the lights go up months before Christmas.

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Households across the world also use lights to celebrate their holidays — whether that’s Christmas, Ramadan or Diwali.

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What does all this mean for the environment? NASA has been monitoring the effects holiday lights have on the Earth from space with its Suomi NPP satellite.

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The space agency’s researchers first noticed an increase in lighting in the Middle East, during Islam’s holy month of Ramadan.

Holiday lights illuminate the planet from space

NASA explained in a video that parts of the Earth are up to 50 per cent brighter during the weeks between U.S. Thanksgiving and New Year’s Day. Suburbs in America are where some of the biggest differences are noticed.

Miguel Roman, a scientist from the NASA Goddard Space Flight Center, explained that the dramatic change in lighting was unexpected.

“We were really surprised to see this vibrant increase in activity during the holidays, particularly around areas in the suburbs with a lot of single-family homes, and a lot of yard space to put up lights.”

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Light pollution

The holiday lighting that illuminates Earth is nice to look at, but brightness in the night sky can have consequences.

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According to Globe At Night, an international organization dedicated to raising awareness about light pollution, excessive outdoor lighting has numerous adverse effects on the planet: it washes out stars in the sky, disrupts ecosystems of nocturnal wildlife, and wastes energy.

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It can even have bad effects on human health, making it difficult to sleep, changing the amount of melatonin produced, causing headaches and increased anxiety.

With Christmas lights, the disruption could be as small is making it difficult for a neighbour whose window is facing a brightly lit home to sleep. Or, with large displays, potentially confusing wildlife.

LED light bulbs vs. incandescent lighting vs. solar power

While London uses hundreds of thousands of bulbs, city officials say they are LED and use 75 per cent less energy than incandescent ones.

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And according to University of Toronto professor Danny Harvey, who studies energy efficiency, Christmas lights aren’t too damaging for the environment anymore because they are mostly LED.

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“It’s an enormous reduction in electricity, the less electricity that is used the less the environmental impact,” he told Global News.

While LED lights don’t completely cut the amount of energy used by holiday lights or solve the problem of adding to light pollution, Harvey says the festive decor should stay up.

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“I wouldn’t tell people not to put up Christmas lights. It’s only for a few weeks of the year,” he explained, adding there are many other meaningful ways to conserve energy year-round.

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LED lights may be slightly more expensive to purchase, but they tend to reduce electricity bills in the long run, Harvey added. They also don’t heat up as much as regular bulbs that can pose a potential fire hazard.

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David Hardisty, a professor at the University of British Columbia who researches sustainability, explained solar powered lights may be another environmentally friendly alternative. But it depends on location.

If someone lives in a city with a lot of sun, and their property gets a lot of sunlight, solar lights may work. Hardisty says those living in places such as Vancouver (where it’s often cloudy) or up north may have difficulty getting the lights to actually light up.

How to have a green Christmas

Opting for LED lighting is just one way to celebrate the season while being sustainable

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BC Hydro explains that Canadians can go a few steps further, by putting timers on indoor and outdoor lights, so they aren’t turned on all the time.

Hardisty notes that energy consumption is typically at a high between 5 p.m. to 7 p.m., so it’s probably not a good idea to use lights at that time.

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“After 7 p.m., electricity goes down overall, so maybe if you have your lights on in the evening it’s not so bad.”

Those who want to conserve energy can also use fewer lights in displays, since there are plenty of other decor options such as ornaments, artificial plants and ribbons.

The UBC professor notes that more lights isn’t always better for a display.

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“That first string of lights you put out, it adds a lot of holiday cheer. Having one string of lights up versus none makes a big difference,” Hardisty explains. “Having having six strings of light versus having five barely makes any difference.”

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“Sure, go for it. But just go for a little bit.”

And finally, Canadians should shorten the amount of time lights stay up — that means actually taking them down after Christmas.