March 18, 2021

Blue light glasses are booming—but do they really work? Here's what the science says.

Daily Briefing
    Editor's note: This popular story from the Daily Briefing's archives was republished on August 4, 2021.

    As more people spend their entire work day in front of a computer, sales of blue light glasses—which incorporate special lenses that filter out certain light waves emitted by digital devices—have boomed. But do these glasses actually offer any benefits? Here's what the research says. 

    Why blue light glasses are all the rage

    Blue light is a relatively low-wavelength, high-energy light emitted by the sun and, to a lesser degree, from digital devices, such as laptops and cellphones. According to the New York Times, blue light been shown to increase attentiveness and wakefulness during the day—but at night, this type of light has been found to suppress our bodies' natural production of melatonin, which can hinder our ability to sleep.

    Companies that produce blue light glasses contend that limiting exposure to the light waves by as little as 20% can improve a person's sleep, lessen their eye strain, and stave off potential damage to their retinas.

    During the pandemic, sales of these glasses have increased dramatically, according to the Times. Several brands that almost exclusively sell so-called "computer glasses" brought in millions in funding in 2020, and prescription-eyewear companies such as Jins, Warby Parker, and Zenni reported substantial increases in blue light glass sales last year.

    "As many customers started working from home last year, we have seen a significant rise in demand for these lenses," Neil Blumenthal, a chief executive of Warby Parker, said. "Last April, we saw a sizable increase specifically for nonprescription blue-light-filtering lenses, and we've seen this trend continue throughout the pandemic."

    The glasses may be helpful—but research is limited

    According to USA Today, there is no research on how blue light may affect people's eyes over the long term.

    However, some shorter-term research suggests the glasses may be helpful, according to Christopher Barnes, a professor of management at the University of Washington's Foster School of Business, who wrote about his own forthcoming study on blue light glasses in the Harvard Business Review.

    For his study, Barnes and his colleagues sought to examine how using blue light glasses at night could affect sleep quality, amount, and work outcomes. The study aimed to build on prior research that found "wearing glasses that filter out blue light can help people sleep better," Barnes wrote.

    Barnes and colleagues conducted two studies: one of 63 managers, and one of 67 customer service representatives. The participants each spent a week wearing blue light glasses and a week wearing identical glasses with no blue light filter—and participants were randomly assigned which glasses to wear in a given week. The researchers asked participants to wear the glasses for two hours before bedtime every night.

    Compared with the week in which the glasses without the blue light filter were worn, participants wearing blue light glasses reported sleeping more (5% and 6% longer among the manager and customer service representative groups, respectively) and having better quality sleep (14% and 11% better, respectively).

    The researchers also found that sleep quality and quantity had a noticeable effect on work outcomes. Compared with the week in which participants wore the glasses without a blue light filter, those wearing blue light glasses reported around 8% better work engagement, around 17% more helping behavior, and just under 12% fewer negative work behaviors.

    According to Barnes, the findings indicate blue light glasses are "an appealing initial step" to improving employees' sleep and overall performance "because they are easy to implement, noninvasive, and—as our research shows—effective."

    Why many experts are skeptical about blue light glasses

    However, many scientists are more skeptical about whether blue light glasses actually provide benefits, the Times reports.

    "Whichever aspect you look at it, it's very hard to justify spending the extra money," John Lawrenson, a professor of clinical visual science at City, University of London, said. Lawrenson and his colleagues looked at several studies testing the effectiveness of lenses that block blue light and determined the glasses are unnecessary.

    Lawrenson noted that digital eye strain is a real issue, but he said, "No one has established an independent causal association between blue light coming from the computer and visual symptoms." He recommended people ask their eye doctors about any symptoms rather than buying nonprescription glasses.

    Separately, another study looked at what happened in 5,000 eyes when a blue light filter was added to a synthetic lens implanted in the eye following cataract surgery. It found no evidence that the blue light filters were beneficial.

    And in fact, the American Macular Degeneration Foundation has directly stated that "there isn't much evidence to support wearing blue-light-blocking glasses for daily electronics use," and the American Academy of Ophthalmology states that blue light from devices will not cause eye disease.

    Separately, Sunir Garg, a retina surgeon and professor of ophthalmology at Wills Eye Hospital, noted that there's far more blue light coming from the sun than our digital devices. "Blue light is something that humans have been exposed to since the dawn of time," he said. "In parts of the world, they're going to get more blue light exposure in any given day than we will sitting in front of our screens."

    Garg added that the human eye does a good job at filtering out blue light, so the amount that actually hits the retina is relatively low. "On one hand, there's a kernel of truth to" concerns about blue light from digital devices, he said. "(But) we do have … sunlight data and it doesn't seem to be dangerous from the sun … which makes me think the screen stuff is overblown."

    According to Garg, eye symptoms related to screen time have more to do with people not blinking or moving their eyes around enough when staring at a device. Instead of using blue light glasses, Garg recommends keeping at least 25 inches between you and your screen and using artificial tears to lubricate your eyes if they get dry.

    And David Ramsey, a retina specialist at the Lahey Hospital & Medical Center, recommended stepping away from the computer screen occasionally. "Using our computers for long periods of time may lead to eye strain. It's important to take breaks," he said. "That has little, if anything, to do with blue light" (Safronova, New York Times, 2/18; Rodriguez, USA Today, 11/13/20; Barnes, Harvard Business Review, 10/14/20).

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