Debunking the “Dangers” of Blue Light


Most of us spend a lot of time using screens. Computer monitors, TVs, gaming consoles, and smartphones compete for our attention every day.

Parents constantly tell their kids that too much screen time will strain their eyes. Many people complain of headaches after too much time working on the computer.

But what’s really going on here? Is blue light really damaging our eyes? If so, how can you protect them?

Double-edged sword

The spectrum of light that we can see is made up of a range of different colours with different wavelengths. For example, what we see as blue has a different wavelength than red. Screens emit many spectrums of light, but sometimes put out a higher percent of blue.

According to Harvard Health, this blue light is a double-edged sword. While blue light actually has the effect of increasing our alertness and reaction time during the day, that same effect may interfere with your natural sleep cycle at night. This can confuse your body into thinking it’s still daytime, causing it to reduce the crucial production of the melatonin it needs to help you rest.

But does it do any actual damage to your eyes?

No evidence of real harm

CBC’s Marketplace investigated some optical chains’ claims that too much blue light may cause retinal damage, eye diseases, or even cancer.  

On the surface, those claims might seem like they make sense, given the sleeplessness, eye strain, and headaches caused by too much screen time. Lenses being sold by those chains that filter out excess blue light would, in turn, seem like the logical choice to protect your eyes.

The optometry experts canvassed in Marketplace’s investigation confirmed that, as it turns out, there is actually no current evidence that would suggest blue light can do any such damage. Issues like tired or strained eyes don’t stem from blue light, they explain, but from staring at screens for a long time.

Going further, Dr. Rahul Khurana of the American Academy of Ophthalmology (or AAO) told Marketplace that the use of blue light filtering lenses could potentially cause “more harm than good”, if people continued eye-straining activities thinking the filtering lenses would protect their eyes from that strain.

Protect your eyes

There is no question that blue light can have a detrimental impact on screen-lovers, it’s just not in the way the big chains might suggest. 

Many devices have “night mode” settings that will reduce the amount of blue light emitted at night. Alternatively, using screens sparingly — or avoiding them entirely — late at night will help to prevent any disruption to your sleep.

As for blue light filtering lenses? They aren’t necessarily harmful in and of themselves, as long as users do not think they are protected from the primary source of eye issues stemming from screen use: strain.

Instead of costly new lenses, the AAO helpfully suggests using the “20-20-20 rule” to protect your eyes: when you can’t take a full break away from your screen, take a break every 20 minutes to look at something 20 feet away for 20 seconds.