The dark side of LEDs: suppression of melatonin by blue light

The dark side of LEDs: suppression of melatonin by blue light

The dark side of LEDs: suppression of melatonin by blue light

Credit: Alicia Dimovski

You may have heard that blue light exposure can disrupt your sleep. Apparently, it is also harmful to wildlife.

At a downtown university, crowds of wallabies are helping researchers understand how artificial light affects nocturnal marsupials.

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

In one enclosure, they were exposed to light-emitting diodes (aka LEDs). A second casing had blue shielded LEDs very similar to the “night mode” setting on your phone or laptop. The 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 sleep. And the level of melatonin produced in our bodies is regulated by a photosensitive protein in our eyes called melanopsin. When certain wavelengths of light hit melanopsin, it suppresses our production of melatonin. Reduced levels of melatonin in our blood could interfere with our body’s natural sleep-wake cycle.

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

“This is because melatonin production is suppressed by light and the peak of 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 copes completely well 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.

Light up

Not all light activates melanopsin equally. Blue light with a wavelength between 420 and 440 nanometers activates melanopsin better.

In 2009, the Australian government began phasing out incandescent globes for energy-efficient alternatives such as LEDs.

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

After 10 weeks of exposure to nocturnal 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 blue light from LEDs made a big difference to melatonin levels. In fact, wallabies exposed to amber LED light had melatonin levels on par with wallabies experiencing natural darkness.

Sleepless in the suburbs

Beyond melatonin, for wallabies, the change in light level during the four seasons is a timer for life processes such as reproduction.

“Animals that breed at a certain time of year, such as tammar wallabies, rely on this biological clock to ensure 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 the full moon due to an increased risk of predation. So even very low levels of light pollution can disturb our wildlife.”

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

“The DBCA promotes guidance 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 spokesperson for the DBCA.

So, if you are looking for the best possible nocturnal wildlife friend near your home, consider purchasing blue wavelength filters for your LEDs and placing them closer to the ground. They will love it!

Light pollution can suppress melatonin production in humans and animals

This article first appeared on Particle, a science news website based in Scitech, Perth, Australia. Read the original article.

Citation: The Dark Side of LEDs: Blue Light Suppression of Melatonin (2022, September 9) Retrieved September 10, 2022 from

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