How to tell the difference between good light and bad light for your skin

As our brief dose of daily sunlight wraps before the clock hits 6 p.m. now, the potential perks of light therapies and laser treatments are coming up in constant conversation. So what are the new guidelines for “good” and “bad” forms of illumination? Sure, we know that if left unprotected, the sun can be a danger because of its direct link to skin cancer. But what about the effects of the light that women face from phone screens or the latest wellness treatments like infrared sauna sessions?

And let’s not forget the seemingly countless lasers and light treatments both at home and at the derm’s office that promise to cure complexion woes such as clearing up acne, boosting collagen production, and ridding bodies of unwanted hair. “Aesthetic lasers can target several skin conditions, including unwanted hair, spider veins, skin laxity, pigmentation issues, and even tattoo removal—often offering multiple treatment modalities on just one machine,” says Andréa Young, co-owner of NYC’s women-run BEAM Laser Spa.

When you take all of this together, it’s clear that a lot of people are in the dark when it comes to light. “We are learning more and more every day about light therapy, and it’s important to understand that the way light interacts with the skin is dependent on many variables,” explains New York City-based dermatologist Bradley Bloom, who notes that the wavelength of light (which determines its color) and the dosage of light are two incredibly important variables that determine how it affects your skin.

So, with new studies about the health and beauty influences of different wavelengths and frequencies swirling, I sought out to create a handy breakdown of which versions of light to embrace and which to avoid. All of that illuminating information, right this way.

Read on to see how various forms of light affect your skin and health.

Sunlight

If you typically slather on a high SPF in the summer or on a beach vacay, but cruise with a basic SPF 15 daily moisturizer when the sun is nowhere to be found, it’s time to get more serious about protection—even in the cooler months. Just because you aren’t out to catch rays, UV light is still present 365. “UVA light can even penetrate glass while we are indoors,” says Dr. Bloom, who cautions that there are two big reasons all skin tones should guard against UV rays. “First, it prematurely ages our skin, and second, it’s carcinogenic, meaning it causes skin cancer.”

Fortunately, breakthroughs in sunscreens can protect us from UVA (long wave ultraviolet) as well as UVB (shorter wavelengths of ultraviolet that are responsible for sunburn). “I recommend sunscreens with an SPF 30 or higher, that are broad spectrum,” says Dr. Bloom, noting that physical blocks such as titanium dioxide and zinc oxide are particularly important for people with sensitive skin. Also important: Make sure to use a version specifically for the face on your face, like Drunk Elephant Umbra Tinte Sunscreen SPF 30 ($36), which along with sun-protecting power, also boosts radiance with antioxidants such as algae and sunflower sprout extracts.

Infrared light

While everyone is constantly in contact with infrared rays emitted from the sun (they help heat the Earth), there are also man-made infrared treatments that act like invisible beauty forces—assisting with everything from boosted circulation to accelerated healing. Case in point: The infrared sauna hotspot HigherDOSE, with acolytes the likes of Selena Gomez and Jennifer Aniston, purports that a session can help lessen muscle discomfort, remove toxins, and amp up calorie burn. (If you’re nowhere near NYC or LA, fear not! HigherDOSE also has an At-Home Infrared Sauna Wrap ($425), which is a sleeping-bag-sized version of their treatment that you can roll whatever your coordinates.)

“Infrared LED light treatments can definitely help the skin but as with all of our light devices the amount of energy delivered, the time period over which it is delivered, and time between treatments is critical,” explains NYC dermatologist Dhaval Bhanusali. And some dermatologists even note that the heat from these saunas have the ability to cause pigmentation conditions, such as melasma to flare up, so monitor your skin closely.

Red light

Red light, while not the same as infrared (red light is visible; while infrared isn’t) is celebrated for its own skin-friendly benefits and is often used alongside infrared for beauty and wellness treatments. “Red light is great for inflammatory conditions and has been shown to help with collagen stimulation,” says Dr. Bhanusali. This type of light has long been used at doctor offices to help lessen lines and take down redness as well as relieve rosacea. Recent advances have allowed the tech to go DIY, which is why you’ve likely seen a slew of at-home red light masks such as the Dr. Dennis Gross SpectraLite Eyecare Pro LED Device ($159) popping up on beauty shelves.

At esthetician’s offices, red light is even being tapped for a full-body treatment. Joanna Vargas, the bicoastal facialist who’s gained a cult following from celebs like Maggie Gyllenhaal, Sofia Coppola, and Dakota Johnson, changed the skincare game when she debuted her LED bed (a mix of infrared and red light) in 2007 and created a new skin-care obsession. “People see their pores shrinking and their skin looks glorious even after just a few treatments,” says Vargas of the bed, which is apparently occupied night and day in NYC. “It reduces inflammation, improving your overall complexion for smoother, younger-looking skin,” she says.

Blue light

All blue light is not created equal and the jury is still out on the dangers of the visible version emitted from our phone screens and other electronic devices. “While there is data to suggest that visible blue light can have negative effects on our circadian rhythm and sleep cycle, there is no evidence it causes skin cancer,” says Dr. Bloom. He notes that until further studies surface, dermatologists are focusing on the “good” version of blue for in-office and at-home treatments. “Much of the evidence we have about the effect of this type of blue light on the skin demonstrates how it can be used to treat conditions such as acne,” he says. That’s because blue light is able to banish bacteria lurking deep within skin, which can often cause consistent breakouts and topical products can’t target (at home, try a device such as Dr. Bhansali is a fan of portable acne treatments like Foreo Espada Acne Blue Light  ($149) that utilize the wavelength’s antibacterial strengths). “I also really like the Neutrogena Light Therapy Acne Mask ($30) as an at-home supplement to what we do in our office,” he says, adding that its mix of blue and red light is designed to combat bacteria as well as inflammation, two culprits of acne that often go hand in hand. “While it’s been mainly marketed for acne, because it has red light, too, I even like it for stimulating collagen and easing the signs of aging,” he says.

Dr. Bhanusali seconds the notion of “good” versus “bad” blue light. “There is some early research indicating that the blue light from screens may cause some changes in the skin, including hyperpigmentation,” he explains. Which is why this new cutting edge research is also making a link between this form of blue, emitted from tablets, smart phones and computers and its effect on worsening melasma. And you may want to be wary of handheld devices for yet another reason. “While there doesn’t seem to be enough support that it can cause DNA damage yet, it’s worth noting that at the beach or out in the sun, the reflection from the screens can actually cause further UV exposure and harm,” explains Dr. Bhanusali.

Lasers

While these may sound like they’re from the space age, lasers (which fun fact, actually stand for “light amplification by stimulated emission of radiation”) have become so commonplace that now it’s no biggie when your doc aims one (literally!) at your skin. Unlike the LED red and blues, which have gone DIY, true lasers are for pros only, and the versions are more high-tech than ever.

According to experts, the newest speed of light helps reduce downtime associated with in-office complexion treatments for issues like hyperpigmentation and tattoo removal. “We were previously limited to nanosecond lasers, but with the development of picosecond lasers (like Cutera’s Enlighten treatment), we are able to treat tattoos more effectively and are using these devices for no-downtime skin revitalization and toning,” says Dr. Bloom of the technology that operates at one trillionth of a second.

While many people used to wait until winter to book their laser hair removal sessions due to lasers’ inability to treat darker tones and suntanned skin, Nd:YAG lasers (which are in the infrared zone) are making the impossible, possible. “The wavelength this laser uses means clients of any skin tone can be treated year round,” says Young, who strictly uses lasers that feature this technology. Of course, anyone with ultra-sensitive skin may still opt to get zapped during darker winter months to see the best results. Here’s to keeping the darkest months a little brighter.

Looking for more ways to get your skin pretty naturally? Check out these editor-tested winter skin treatments. And now that you know the ins and outs of sun protection, time to start shielding skin from pollution, too.