Risks of Blue Light From Devices

By Nicolas Lebrun | November 8, 2019

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Is the light from your screen damaging your eyes?

Are there reasons to worry about the potential adverse effects of electronic device use? Among the more alarming are claims that the high-intensity blue light emitted by smartphone, tablet, and laptop displays may be responsible for disrupting sleep, causing eye strain, and, most disconcertingly, precipitating vision loss.

These concerns have proliferated to such an extent that Apple and Microsoft have adopted software capable of shifting the color gradient on screens to warmer, presumably less-harmful hues. Some companies are even selling glasses costing more than $90 that claim to eliminate all exposure to blue light. But are these measures appropriate in light of scientific research? And what actually is blue light?

What is “Blue Light”?

Although it is difficult to determine at a glance, much of the light we come into contact with throughout the day is composed of high-energy blue light waves. Blue light is considered “high-energy,” as compared to, say, green light because waves at the limits of the visual spectrum — such as blue and violet — require more energy in order to be perceived at the same level of brightness. The fear is that this higher energy output can damage cells in the retina, hastening age-related vision loss.

This issue is particularly pressing given that artificial lighting in general, and not only the light which emanates from our screens, is disproportionately composed of blue light. This is due to the fact that pairing a blue LED with a low-energy phosphor is a cost- and energy-efficient way of reproducing white light similar to the light of the sun. 

Indeed, the most powerful source of blue light we’re subject to is not any of these sources of artificial lighting, but the sun. This is one of the reasons to be wary of marketing campaigns urging you to save your eyes; blue light is nothing new, and we’re regularly exposed to it in much higher intensities. Further, experiments tying blue light exposure to vision loss has been largely disregarded by experts, as they weren’t conducted in ways that replicate how cells are actually exposed to light. 

There are still a number of smaller risks to consider, but the more apocalyptic ones do not reflect the current state of the research.

The most significant of these risks are the negative effects blue light can have on sleep. Screen time during evening hours can make it harder for you to fall asleep because the biological process that determines our sleep and wake cycle is regulated by outside stimuli such as the light from the sun. When we’re exposed to artificial lighting once the sun has gone down, mechanisms suppressing the secretion of melatonin — the hormone responsible for making us feel tired — may be triggered. Conversely, exposure to blue light during the daytime has been tied to a number of positive side effects including increased focus, mood, and wakefulness. 


The American Association of Ophthalmology (AAO) cautions against taking premature preventative measures — such as purchasing 90 dollar blue light filter glasses — as they may risk causing unintended, unforeseeable consequences.

Regarding the occasional eye strain that occurs throughout the workday, this is likely due to the fact that people blink about a third as often when using computers as they normally do. A solution that the AAO recommends is the 20-20-20 rule: anyone working behind a screen for an extended period of time should take a break every 20 minutes to stare at an object at least 20 feet away, for around 20 seconds.

Familiar wisdom regarding screen use largely holds true. Avoid looking at a screen two to three hours before bedtime. Even though they can’t entirely block the output of blue light, filter apps such as f.lux and nightshift can be helpful when browsing after the sun has gone down.