READ

The dark side of LEDs

You may have heard that exposure to blue light can disrupt your sleep. As it turns out, it's also harmful to wildlife.
Thomas Crow
Thomas Crow
Freelance science writer
The dark side of LEDs
Image credit: Alicia Dimovski

At an inner-city university, mobs of wallabies are helping researchers understand how artificial light affects nocturnal marsupials.

La Trobe University graduate researcher Alicia Dimovski is studying how exposure to light affects tammar wallabies.

In one enclosure, they were exposed to light-emitting diodes (aka LEDs). A second enclosure had blue-shielded LEDs much like the ‘night mode’ setting on your phone or laptop. Wallabies in a third enclosure experienced natural darkness.

After 10 weeks, Alicia took blood samples to test the wallabies’ melatonin levels. As it turns out, LEDs have a dark side.

 

The ‘hormone of darkness’

Like us, wallabies rely on the hormone melatonin for a good night’s rest. And the level of melatonin produced in our bodies is regulated by a light-sensitive protein in our eyes called melanopsin. When certain wavelengths of light hit the melanopsin, it suppresses our melatonin production. Reduced levels of melatonin in our blood could mess with our bodies’ natural sleep-wake cycle.

 

Melatonin molecule

Image credit: getty images
Melatonin molecule

“Melatonin is known as the ‘hormone of darkness’,” says Alicia.

“This is because production of melatonin is suppressed by light, and peak production occurs during the dark phase.”

Melatonin is also important for the immune system. In mammals, melatonin acts as an antioxidant, capturing free radicals.

Free radicals are unstable atoms created by the body as a byproduct of various normal cellular processes. Despite their potential to damage DNA and other cells, the body does completely fine with low levels of free radicals. However, when we have an infection, the body’s immune response can cause an increase in free radicals. Without melatonin, this increase in free radicals can cause oxidative stress, which increases inflammation.

 

lighten up

Not all light equally activates melanopsin. Blue light with a wavelength between 420–440 nanometres is better at activating melanopsin.

In 2009, the Australian Government began to phase out incandescent globes for energy-efficient alternatives like LEDs.

Since then, LEDs have become the primary source of light for Australian homes, businesses and streetlights. Unfortunately, the energy-efficient light bulbs are causing health problems for nocturnal wildlife.

View Larger

Wavelengths of light from normal (left) and blue-filtered LEDs (right)

Image credit: Alicia Dimovski
Wavelengths of light from normal (left) and blue-filtered LEDs (right)

After 10 weeks of exposure to night-time LEDs, Alicia’s wallabies had lower melatonin levels.

“White LEDs cause problems because they contain a large amount of blue light, so they are really effective at suppressing melatonin,” says Alicia.

However, the study found that removing the blue light from the LEDs made a big difference to melatonin levels. In fact, the wallabies exposed to amber LED light had melatonin levels on par with wallabies experiencing natural darkness.

“While we can use a night-shift or blue-light filter on our devices, our wildlife isn’t so lucky.”

SLeepless in suburbia

Beyond melatonin, for wallabies, the changing level of light throughout the four seasons is a timer for vital processes like reproduction.

“Animals that breed at a certain time of year, such as the tammar wallabies, rely on this biological clock to ensure that births occur when there is enough food to raise their young,” says Alicia.

“Many Australian mammals have been shown to reduce their activity even under a full moon due to an increased predation risk. So even very low levels of light pollution can disrupt our wildlife.”

The WA Department of Biodiversity, Conservation and Attractions has guidelines for businesses to reduce light pollution. However, they’re not legislated or enforced. Compliance with the guidelines is completely voluntary.

“The DBCA promotes the guidelines through education with industry and government agencies to ensure best-practice lighting design and reduce the potential impact of artificial light on wildlife,” says a DBCA spokesperson.

So if you wallaby the best friend you can to nocturnal wildlife near your home, consider getting blue-wavelength filters for your LEDs and placing them closer to the ground. They’ll love ‘roo for it!

Thomas Crow
About the author
Thomas Crow
Thomas Crow is an Australian science writer. He has a background in professional writing, biochemistry and genetics. He writes for Australian and New Zealand research institutes and publications like Crikey. He's a horror and gothic fantasy fan. He thinks of himself as a gardener but scores of dead plants beg to differ.
View articles
Thomas Crow is an Australian science writer. He has a background in professional writing, biochemistry and genetics. He writes for Australian and New Zealand research institutes and publications like Crikey. He's a horror and gothic fantasy fan. He thinks of himself as a gardener but scores of dead plants beg to differ.
View articles

NEXT ARTICLE

We've got chemistry, let's take it to the next level!

Get the latest WA science news delivered to your inbox, every fortnight.

This field is for validation purposes and should be left unchanged.

Republish

Creative Commons Logo

Republishing our content

We want our stories to be shared and seen by as many people as possible.

Therefore, unless it says otherwise, copyright on the stories on Particle belongs to Scitech and they are published under a Creative Commons Attribution-NoDerivatives 4.0 International License.

This allows you to republish our articles online or in print for free. You just need to credit us and link to us, and you can’t edit our material or sell it separately.

Using the ‘republish’ button on our website is the easiest way to meet our guidelines.

Guidelines

You cannot edit the article.

When republishing, you have to credit our authors, ideally in the byline. You have to credit Particle with a link back to the original publication on Particle.

If you’re republishing online, you must use our pageview counter, link to us and include links from our story. Our page view counter is a small pixel-ping (invisible to the eye) that allows us to know when our content is republished. It’s a condition of our guidelines that you include our counter. If you use the ‘republish’ then you’ll capture our page counter.

If you’re republishing in print, please email us to let us so we know about it (we get very proud to see our work republished) and you must include the Particle logo next to the credits. Download logo here.

If you wish to republish all our stories, please contact us directly to discuss this opportunity.

Images

Most of the images used on Particle are copyright of the photographer who made them.

It is your responsibility to confirm that you’re licensed to republish images in our articles.

Video

All Particle videos can be accessed through YouTube under the Standard YouTube Licence.

The Standard YouTube licence

  1. This licence is ‘All Rights Reserved’, granting provisions for YouTube to display the content, and YouTube’s visitors to stream the content. This means that the content may be streamed from YouTube but specifically forbids downloading, adaptation, and redistribution, except where otherwise licensed. When uploading your content to YouTube it will automatically use the Standard YouTube licence. You can check this by clicking on Advanced Settings and looking at the dropdown box ‘License and rights ownership’.
  2. When a user is uploading a video he has license options that he can choose from. The first option is “standard YouTube License” which means that you grant the broadcasting rights to YouTube. This essentially means that your video can only be accessed from YouTube for watching purpose and cannot be reproduced or distributed in any other form without your consent.

Contact

For more information about using our content, email us: particle@scitech.org.au

Copy this HTML into your CMS
Press Ctrl+C to copy