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A woman reading on her digital tablet during the night.draganab/iStockPhoto / Getty Images

This year, I’ve developed the habit of wearing sunscreen indoors. As my technology use skyrocketed, I began wondering if the cumulative impact of hours spent basking in the blue glow of Word documents and Zoom calls may be etching itself into my face somehow – and whether the basic care we know to take with our skin in the sun has merit even when we’re spending the day inside, online.

But are my concerns reasonable, or a symptom of cooped-up fretfulness gone supernova? I asked some experts to explain the ins and outs of blue light, which, as it turns out, can be bad or good – and even beautifying – depending on its context.

Blue light is a short-wavelength, high-energy visible light that primarily affects us via sun exposure, but it is also emitted to a lesser degree from the screens of our phones, computers and televisions. It contributes to skin dullness, spots, wrinkles and dryness. “Blue light basically does the same thing as long-wavelength UVA,” says Alexander Wolf, a senior assistant professor at Nippon University, who has studied its effects on skin. “Blue light induces oxidative stress. And because oxidative stress can damage DNA, this can cause aging.”

Sufficient long-term studies on the aggregate impact of blue light from technology on the skin are lacking, though recent research by Unilever claims that if you spend six hours on your device daily, your workweek is having the equivalent effect on your face as 25-minutes in the midday sun without protection. “The intensity of blue light you get from the sun is 100-fold higher than that from a smartphone,” says Wolf. “That doesn’t mean it’s completely harmless, but spending an hour in front of a screen could cause as much damage as a few seconds in the sun.”

If that doesn’t warrant applying sunscreen indoors, consider the possibility of sun exposure for those lucky enough to be working beside a big window. “People need to wear sunscreen when they’re indoors because ultraviolet light as well as visible light containing blue light gets through windows. And there is now this concern that we are getting a small portion of blue light from screens as well,” Toronto dermatologist Dr. Julia Carroll says. She recommends using a sunscreen with a physical blocker like zinc oxide or titanium dioxide (chemical sunscreens do not protect you from blue light), and an antioxidant daily to fend off any unwanted effects. “L-ascorbic acid, which is a form of vitamin C, is the gold standard,” she says.

Blue light from devices affects our well-being in other ways, too, such as contributing to macular degeneration and eye strain. The easiest way to protect your eyes from the latter is to use the 20-20-20 method: Every 20 minutes while using your device, look up and at something 20 feet away for 20 seconds. Blue light blocking apps, screen shields, or yellow-tinted glasses may be able to help, though, to avoid quack products, consult your optometrist.

Studies have found the blue light our devices emit is also enough to disrupt our circadian rhythms by suppressing melatonin, leading to poorer sleep, itself linked to higher precedence of diabetes, depression and cardiovascular issues. The flip side of this effect is that blue light can help keep you alert and seems to have a positive impact on mood, making it an ally to anyone struggling to pull an all-nighter.

There are other reasons we can’t simply label blue light as “bad.” It’s also been harnessed by dermatologists since the 1960s, with controlled doses used to treat everything from infant jaundice to psoriasis, extreme acne, rosacea and some precancerous and cancerous skin lesions, says Dr. Jason Rivers, head of the Canadian Dermatology Association.

“It seems that blue light has sort of an anti-inflammatory and anti-proliferative effect on the skin,” when used in a controlled setting, says Rivers. In the form of intense pulsed light or photodynamic therapy treatments, blue light can help target sun damage, age spots and uneven skin texture.

It’s also anti-microbial, making it a helpful tool in the fight against acne. “Patients find their spots clear more quickly, they have less breakouts and the appearance of scars and marks is improved,” says Carroll, who uses blue light to treat acne in her practice. “Results are seen after the first treatment, but get cumulatively better.”

Yet many of the benefits of blue light only apply to lighter skin tones. “For reasons that aren’t totally clear, people of colour can experience more pigment change from blue light than people of lighter skin,” says Rivers. Indeed, a 2010 study published in the Journal of Investigative Dermatology found that levels of blue light that had no negative effect on light skin tones produced hyperpigmentation in medium to dark tones.

When it comes to skin care, it pays to know your enemy. Blue light can be a friendly foe, but on a day-to-day basis, I’m going to keep my defences up.

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