Wednesday , March 3 2021

Should you add a blue light filter to your glasses?

Blue light and sleep

Sean Cain, a sleep researcher and an associate professor of psychology at Monash University, says the increasing exposure of Australians to artificial light is "a health problem."

Exposure to blue light before bedtime can affect our ability to sleep in three ways: suppressing the production of melatonin in our body (which helps us to sleep), increasing alertness and affecting our body's internal clock (or rhythm circadian).

"Even if it's at 11 o'clock, you're giving your clock a signal that it's a day, several hours before, and then it's harder to sleep," explains associate professor Cain.

There is also evidence that exposure to blue light can affect the quality of sleep you have at night: a 2013 study conducted by Swiss researchers found that exposure to light blue even at relatively low levels (ie sitting in a room lighting by a standard LED lamp) can decrease the amount of slow-wave sleep (the most restorative type of sleep) that a person has in the early evening.


Because it is not just your phone that is causing problems. Although humans are exposed to less blue light each day than we would have received from the sun while living many outdoor lifestyles centuries ago, our exposure is now occurring through artificial sources in unnatural times, especially when the sun sets put.

"Most Australians have a lot of blue light in their environment because of the decision to switch to more energy-efficient LEDs," said associate professor Cain.

"This is good for saving some money on energy, but replaced the light that had less effect on our internal clock.Now we have these LEDs, which are very enriched in blue, and we have them in our homes all the way up to bed . "

Can blue light damage your eyes?

The short answer to this question is: yes, but probably not at the levels at which you are exposed to it.

Much of the marketing around blue lenses is focused on daytime screen usage – Bailey Nelson's website claims that the filter "helps reduce eye strain caused by screens and devices," while the Oscar Wylee blue light lens is "for those who spend their days in front of a computer screen" – and how this can lead to visual fatigue.

However, a spokeswoman for Optometry Australia and Sophie Koh of Melbourne says more evidence is needed to know if exposure to blue light specifically causes visual fatigue, an idea that arose as a result of "smaller studies and anecdotal evidence ".

"Research is ongoing in this area and there are many other components that contribute to digital eye fatigue or" computer vision syndrome, "she says.

For more serious eye problems, this is unlikely to be caused by the habit of the smartphone.


A 2018 report from the New Zealand government science organization, Royal Society Te Apārangi, found that while retinal damage may occur after high intensity exposure to blue light, this would require a much greater blue light level than emanated by an LED screen.

With this evidence, Koh says "at this stage … we do not have to worry about computers or phones that" fry "our retina.

"Recent research has shown that even under extreme conditions, the level of exposure to blue light from computer screens and mobile devices is lower than that absorbed by natural light, and this is below international safety limits," she says.

Blue light glasses: are they worth the investment?

If you are worried about your tired eyes from sitting at a computer all day long, Koh recommends seeking the advice of an optometrist to rule out common vision problems such as uncorrected refractive errors (which can be corrected with a prescription) or dry eye.

There are also other measures such as following the 20-20-20 rule – every 20 minutes, look up your screen and at least 20 feet (six meters) for distance for 20 seconds – or by using an application such as F. lux. or Apple Night Shift to filter the blue light on your smartphone, which can be useful.

But if you're looking to improve the quality of your sleep, Associate Professor Cain says that he would be "very supportive" to someone wearing blue filter glasses at night, especially putting their glasses on at the same time every night to encourage the body to develop a regular circadian rhythm.

However, he cautioned against wearing glasses with strong blue light filters during the day, as this could "potentially" affect alertness.

"It has not been tested directly, but we know that blue light is alert during the day, so exposure to lots of blue light during the day can be very good, not just to alert you, but [also] giving his body a strong sign that it's day, "he says.

"If you're blocking this, you're in a situation where there is not enough signal for your clock to tell the difference between day and night. I think it would be a terrible idea to use these things all the time." of the day. "

And if you want to buy blue light glasses so you can send text messages until dawn, keep dreaming: Ultimately, no pair of special glasses will hit before going to bed.

"It's obvious that if you're using devices in a way that makes you more active – whether you're looking at work emails or worrying about the next day – it will be harder to fall asleep."

Mary Ward is a lifestyle editor for The Sydney Morning Herald and The Age.

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