What is all that screen time doing to your skin?

You've probably heard more about the perils of blue light lately because our lives are more likely to be lived indoors and online. Our laptops, phones, tablets, TVs and even LED light bulbs are all sources of blue light. And now that we're tethered to those devices, are we getting drenched? Should we be more worried about damage to our skin?

This is what we know: Compared with the well-understood dangers of ultraviolet light (skin ageing and cancer), science isn't settled on the effects of indoor sources of blue light on skin. It can cause hyperpigmentation and premature ageing, but the rest — what dose of it causes trouble, for instance — was debated well before we were confined to our homes.

Here, we've checked in with some blue light and skin experts to help explain the real risks.

What is blue light?

When we think about the harmful effects of light, we're usually thinking ultraviolet light (UV), which is invisible. But we can see blue light. You may perceive it as a cool-toned white light (as with an LED light bulb), or you may not be aware of much blue at all. That's because your indoor light sources are emitting varying wavelengths that combine to create the colours you perceive.

Though the effects of blue light on the skin are yet to be fully understood, the light is an important health concern because of its other risks. "Blue light damages the retina and reduces your excretion of melatonin, so it interrupts your sleep cycle," said Michelle Henry, a dermatologist in New York.

Proximity is, of course, a factor when thinking about the danger. "You'll get less blue light from your TV than from your computer because it's farther away," Henry said. "And more light from your phone than your computer because your phone is so close to your face."

How does blue light damage my skin?

While ultraviolet light damages cells' DNA directly, blue light destroys collagen through oxidative stress. A chemical in skin called flavin absorbs blue light. The reaction that takes place during that absorption produces unstable oxygen molecules (free radicals) that damage the skin.

"They go in and basically poke holes in your collagen," Henry said.

Exposure to blue light is more problematic for skin of colour. In a 2010 study published in The Journal of Investigative Dermatology, it was shown to cause hyperpigmentation in medium to dark skin, while leaving lighter skin relatively unaffected.

The medical community categorises skin colour based on how it reacts to UV light. Type 1 is the lightest colour with the most UV sensitivity. "This would be Nicole Kidman and Conan O'Brien," said Mathew Avram, director of the Massachusetts General Hospital Dermatology Laser and Cosmetic Center in Boston. The scale goes up to Type 6, which is the darkest and least likely to burn.

In the 2010 study, Type 2 skin was exposed to blue light but didn't develop pigmentation. Skin of colour darkened, and that darkness persisted for a couple of weeks.

"There is something about the pigmentation in Types 4, 5 and 6 that reacts differently than in patients with fair skin," Avram said. "There should be more large-scale studies looking at this because pigmentation is one of the biggest patient concerns and the one where treatment creates less patient satisfaction."

But isn't blue light used to treat acne?

Yes, blue light lamps treat acne and precancerous lesions. "It damages the skin, but on the other hand it can treat acne," Avram said. "It can help your mood and memory as well. So it's more complicated than just saying 'good' or 'bad'."

How can I prevent skin damage?

The simplest intervention is to limit the amount of blue light emitted from your devices. Apple products have "night shift" that creates a warmer screen tone. Swap out your standard LED bulbs for versions that emit less blue light.

Mineral sunscreens with iron oxides are the gold standard in blue light protection. Iron oxides have been shown to be more protective against visible light than zinc oxide and titanium dioxide alone.

"A good cheat for this is any tinted sunscreen, which usually has iron oxide," Henry said. Skinbetter Science Sunbetter Tone Smart SPF 68 Sunscreen Compact, $US55 ($83), is one such mineral sunblock. The formula combines zinc oxide, titanium dioxide and iron oxide, and it blends smoothly, even on brown skin.

Topical antioxidants should help tame the free radicals blue light creates, but again, the science isn't fully formed.

"I cannot recommend antioxidants from a purely scientific perspective," said Alexander Wolf, a senior assistant professor at Nippon Medical School in Tokyo and an expert in how light and oxidative stress cause premature ageing. "But there are certainly a lot of experiments that show antioxidants work well in cultured cells. Vitamin C enters the cells directly, and if you do some oxidative damage to the cells, the vitamin C or some antioxidant definitely helps."

"But a dish with some cells is not skin," Wolf added.

As long as you're clear that antioxidants haven't been proven to work on blue light, but would probably work, they are a good substitute for sunscreen if you feel weird about sitting at home with a face full of minerals. It's likely that antioxidants will also minimise the damage of a blue LED light device used at home to treat acne. (A mineral sunscreen would block the blue light and stop its bacteria-killing action.)

As far as antioxidants go, vitamin C is a good choice because the molecule is actually small enough to penetrate the skin. Hyper Skin Hyper Clear Brightening Clearing Vitamin C Serum, $US36, contains 15 per cent vitamin C paired with vitamin E, and the two ingredients boost each other's potential to fight free radicals.

The buzz around blue light has led to new lines like Goodhabit. Its Rescue Me Glow Potion Oil Serum, $US80, combines marine-sourced proteins with exopolysaccharides — that is, polymers secreted by micro-organisms that create a protective barrier over the skin. The polymers act like a sunscreen that blocks blue light (rather than neutralising free radicals like an antioxidant).

Though alpha-lipoic acid is not touted for its blue light protective qualities, Wolf has studied its effect on oxidative stress (in mouse skin) and thinks it is promising for human skin.

"It works differently than an antioxidant," he said. "It activates the natural defences of the skin cell by tricking the skin cell to think, 'Oh, there is oxidative stress.' The cell turns up its own defence mechanisms. I think that's a much more elegant way to defend yourself."

Perricone MD High Potency Classics: Face Finishing & Firming Moisturizer, $US69, contains both vitamin C and alpha-lipoic acid.

One important fact is often left out of the blue light conversation: The sun is by far our most abundant source of blue light.

"Brightness is not something the human eye is good at gauging because the pupil adjusts," Wolf said. "You may think your tablet or smartphone is bright, but as far as the amount of light reaching your skin, it is very weak, especially compared to the sun."

All things considered, then, your blue light exposure may well be down when compared with your pre-pandemic life for the simple reason that you're spending more time indoors.

The New York Times