These animations of cities from space reveal a troubling new trend

Astronauts aboard the International Space Station are snapping photos of Earth at night, and the images are telling a surprising story.

A citizen science project called Cities at Night has discovered that most light-emitting diodes (LEDs) — which are touted for their energy-saving properties — actually make light pollution worse. What’s more, the changes in some cities are so intense that space station crew members can see them from orbit.

Take a look at the major metropolitan cities that switched to LEDs in the animations below, which Tech Insider made from astronauts’ photos. The results are as astonishing as they are mesmerising.

Milan -- 2012 and 2015

Before Milan transitioned to LEDs, in 2012, the lighting levels in the surrounding suburbs were about the same as those of the city center.

But by 2015, after the city transitioned to LEDs, illumination levels in the city center were much brighter than those of the suburbs, with a higher amount of blue light:

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Los Angeles -- 2010 and 2012

Los Angeles also went through a dramatic change in a two-year period.

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Mexico City -- 2003 and 2011

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Seoul -- 2011 and 2014

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These aren't the only cities affected.

Others around the world have been replacing energy-guzzling streetlights with brighter and whiter energy-saving LEDs. In fact, New York City is now retrofitting all of its 250,000 street lights with LEDs in what the city is calling the biggest project of its type in the country.

But energy savings does not necessarily translate to happy city dwellers. In a piece in The New York Times, Brooklyn residents complained about the glaring white light creeping into their homes and eyes, causing many restless nights.

LEDs also worsen light pollution by giving off more blue and green light than the high-pressure sodium lights they normally replace. And this artificial light pollution washes out the night sky and is linked to many negative consequences. Disrupted night and day cycles can confuse nocturnal animals and alter their hunting interactions, migratory patterns, and internal physiology.

It can also mess with our internal clocks. We produce melatonin at night to help us sleep, which is regulated by light and dark cycles. If we're exposed to light at night, this can suppress melatonin levels, leading to sleep disorders or other problems such as headaches, anxiety, and obesity.

Cities at Night is compiling these images to make a Google-Maps-style map of images of Earth at night. If you want to support their research, check out their KickStarter project here.

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