Reality check: Does the blue light in your phone actually hurt your eyes?

If you wear glasses, you’ve probably been recommended a special coating for your lenses to shield your eyes from blue light.

Blue light is at the end of the spectrum of visible light and it plays an important part in our ability to be alert, said Dr. Michael Nelson, president of the Canadian Association of Optometrists (CAO).

“When we wake up, the morning light is beneficial; it helps us become more alert and more awake,” he said.

It’s emitted from your smartphone, tablet and computer, but one of the biggest sources of blue light is actually the sun — you’re exposed to blue light whenever you step outside, said Nelson.

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In the past few years, there has been plenty of discussion about the potential negative side effects of blue light. However, doctors like Nelson worry some of it has been misleading.

“We don’t have the evidence to show one way or another [the damage blue light] could have,” he said. “It’s hard to make that stretch.”
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The results of a 2018 study at the University of Toledo found consistent exposure to blue light leads to macular degeneration, a leading cause of blindness.

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Shortly after the study was published, it was widely reported that blue light from your phone or your computer can cause blindness.

In response, the American Academy of Ophthalmology published a statement saying the opposite: “blue light from electronic screens is not making you blind.”

The Verge also asked Ajith Karunarathne, lead author of the study, if using your phone or tablet can lead to blindness.

“Absolutely not,” he said.

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The study did not show that blue light is damaging the eye itself — it just showed how blue light could potentially cause damage.

Specifically, researchers proved that a molecule in the eye called retinal, when combined with blue light, can kill cells.

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More research is needed to determine exactly how blue light affects the human eye, but until then, experts worry results like these can be misleading.

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So, will blue light damage your eyes?

There is evidence to show that blue light — both from the sun and your phone — can disrupt your circadian rhythm, which governs your body’s energy levels based on the anticipated cycles of day and night.

It regulates hormones, blood pressure, body temperature and metabolism over a roughly 24-hour cycle, so the body knows when to wake up, eat and sleep each day.

“Blue light from your screens could be keeping you up, affecting your sleep and making you feel less rested the next day,” said Dr. Cody van Dijk co-chair of the public relations committee at the Manitoba Association of Optometrists.

However, more research on human eyes needs to be done.

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“Studies (like the one at the University of Toledo) have shown that blue light can affect cells or non-human eyes in laboratory environments, but it’s very important to remember that these experimental conditions do not mimic real life,” van Dijk said.

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“It’s not comparable to screens … we can’t equate this study environment with real life and we can’t equate the blue light they use in those studies with the light coming off your device.”

For example, a new study out of Manchester University tested light of different colour and found that when light was dimmed, blue light was “more restful” than yellow light.

The study, however, was performed on mice — not humans.

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For this reason, van Dijk worries the results of these studies are being misinterpreted and, in some cases, blown out of proportion.

“We know that blue light is affecting our sleep, but there is not significant evidence to suggest that the blue light from your device is harming your eyes in any way.”

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Nelson also fears there’s been “self-generated buzz” online about blue light filters and what they can do to “protect” your eyes.

“There’s not a lot of evidence that says one way or another, this is beneficial,” he said.

He also notes that exposure to blue light while outdoors is much more severe than anything you get from your phone or computer.

“We get blue light from all our devices, but when you walk outside, you’re also exposed to blue light,” he said. “The amount of blue light you’re exposed to outdoors is probably 30 times as much as you get from your device, which I believe is more cause for concern.”

If research finds that exposure to blue light is harmful, there could be some benefit to using light filters outdoors, said Nelson, but right now, that isn’t the case.

‘Digital eye strain’

If you’ve ever sat at a computer for longer than a few hours, you’ve probably experienced symptoms like blurred vision, trouble focusing your vision and even headaches. This is known as digital eye strain.

“We know that using devices, whether it’s your phone or tablet or computer, that can cause eye strain, but there are no studies to show that’s linked to blue light,” said Nelson.

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Digital eye strain is caused primarily by dryness, said Nelson, which occurs when you use devices because you blink less. This can make it more difficult to focus in the long run.

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“Focusing issues and dryness can definitely cause fatigue, but somehow, blue light has gotten linked in there as well,” he said.

“We know blue light can affect your sleep cycles, but there aren’t any studies that show [digital eye strain is] directly linked to blue light.”
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Blue light filters have not been shown to help with digital eye strain, van Dijk adds.

“A blue light filter has no greater effect on computer strain than just using a general filter,” he said.

“We blink less when we’re looking at screens, and when we look at things up close, our eyes’ focusing muscles have to flex and those muscles can get tight, just like any other muscle can,” van Dijk said.

Unfortunately, digital eye strain can lead to cumulative damage over time if you don’t take the proper steps to mitigate it.

According to the CAO, it can lead to headaches, blurred vision, eye irritation, double vision, excessive tearing or dry eyes, eye pain or excessive blinking.

How to protect your sleep and your eyes

When it comes to keeping your circadian rhythm in check, van Dijk recommends avoiding your phone for two hours prior to sleeping.

“If the screen is unavoidable, we can shift our smartphone display to a warmer colour,” he said. “There are apps or settings that can do that automatically.”

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It can also be helpful to change bedroom lighting to a warmer colour, and for some people, reading glasses with a blue light filter can also help.

Trouble focusing, a common symptom of digital eye strain, can be mitigated by updating your lens prescription.

— With files from Josh Elliott

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