Light from mobiles and computers shortens life

Prolonged exposure to blue light, like that from phones, tablets, computers and some TVs, affects the lifespan of banana flies - even if it doesn't shine directly in their eyes.

The light from your smartphone and computer comes from LEDs that emit light in the blue wavelengths - wavelengths that have been shown to damage both the retina and brain cells of banana flies

That's the conclusion of a research project from Oregon State University in the US, which studied the biological clock of Drosophila melanogaster - banana flies - by exposing them to different light sources and darkness.

Banana flies exposed to blue light for a month lived half as long as flies with less exposure to the special light.

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Blue light for a month halved the life of flies

Banana flies exposed to direct blue light had damaged brain cells, damaged retinas and reduced movement. This was reflected in their reduced ability to climb enclosure walls and their otherwise normal 'fly behaviour'.

In other words, the amount of blue light shortened the life of the flies and they aged faster - compared to the others. Older flies suffered most, experiencing more stress from blue light than younger ones.

The experiment showed:

  • Banana flies exposed to blue light for 12 hours every day for 25 days and then transferred to complete darkness lived 60 days on average.

  • Flies exposed to 12 hours of blue light every day for 30 days and then transferred to complete darkness lived only 34 days on average.

  • And flies in total darkness lived 69 days on average.

So flies exposed to 12 hours of blue light and 12 hours of darkness for one month lived 51% shorter than flies in total darkness.

The lifespan ofa normal banana fly is between 60-80 days.

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Blue light destroys our sleep rhythm

Natural light is essential for our biological clock. It is important for health, physiology and psychological behaviour.

However,research is shedding new light on the side effects of too much artificiallight - such as LEDs.

Human eyes are taking in increasing amounts of light in the blue spectrum - in line with our generally increasing screen use.

It's the blue light's short waves that cause problems for our sleep and circadian rhythms - more than the intensity of the light, researchers conclude. Similarly, it was largely the short waves that shortened the lives of banana flies.

Many LEDs in tablets, smartphones and computer screens emit light with a wavelength of 460 nm - the blue light spectrum covers light between about 380-460. But the light appears white because it is often "blurred" by a broad-spectrum yellow phosphate.

Children can suffer visual damage

The banana fly experiments do not show how human brains respond to overexposure to blue light. But according to research leader and Professor of Integrative Biology at Oregon State University, Jaga Giebultowicz, it offers a clue:

"There is a lot of evidence that artificial light poses a risk for sleep and circadian rhythm disorders." She tells the scientific journal Daily Science and continues:

"But even in the most developed countries, LED light has not been used long enough for us to know what side effects it has on human ageing or longevity."

However, if a report by the French food, safety and health agency, Anses, is to be believed, there is good reason to fear the harmful effects of blue LED light on the retina - even in humans.

Their scientific findings show that humans can suffer retinal damage even from short exposures to high-intensity blue light.

In addition, children are at increased risk of developing the disease macular degeneration - impairment of visual acuity - from prolonged exposure to blue light even at very low intensities, Anses warns. This is because the lenses in children's eyes are not fully developed and therefore let in more harmful light.

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