science of us

‘Light Is My New Drug’

The actually convincing science of light therapy.

Photo: Elizaveta Porodina
Photo: Elizaveta Porodina
Photo: Elizaveta Porodina

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Here is a partial list of what one company promises sitting under a small panel of red lights will improve: athletic performance and recovery (owing to faster muscle recovery and joint repair), sleep (thanks to increased melatonin production and a “healthy circadian rhythm”), and skin quality (because of reduced inflammation and increased collagen production).

These red lights, in this case made by Joovv, are one of dozens of at-home versions of what’s known as light therapy, or photomedicine, or photobiomodulation, a technology based on the idea that light can change us on a cellular level. This past summer, the journal Frontiers in Medicine published an issue dedicated to photomedicine, and its 12 articles have an overwhelming effect similar to Joovv’s marketing copy, covering dermatological concerns like aging, skin cancer, and psoriasis as well as autoimmune diseases like type 1 diabetes. I like the way a 2016 journal article phrases it with a bad joke that gives away the researcher’s quiet exuberance: After a brief overview of peer-reviewed light-therapy treatments (for arthritis, hearing loss, and chemotherapy side effects), the conclusion states that “after decades confined to the ‘scientific wasteland,’ [photobiomodulation] may be finally emerging into the light of day (pun intended).”

In recent years, research on light therapy has moved from the fringes of scientific discovery to something closer to the mainstream; its commercial uses are now following the same path, as these devices, once available only in spas, gyms, or dermatologists’ offices, become increasingly affordable for consumers. Meanwhile, the research is only getting more ecstatic. New studies are showing how light can heal the brain and body of … anything? Everything? That’s an exaggeration, obviously, but just barely, or so I’m beginning to believe.

Something about the sheer breadth of maladies that light therapy can supposedly treat has the effect of making the whole thing seem too good to be true; it starts to sound like an infomercial or maybe something advertised on Joe Rogan’s podcast. It does make intuitive sense that light could change the skin — I know (vaguely) that a baby born with jaundice will often be treated with light. I know (personally, irresponsibly) that if you lie in the sun, your skin will tan or burn. And I know people who’ve seen their seasonal depression lift after using a SAD lamp. But what does something like diabetes have to do with light? There’s even some evidence that neurological problems, including Alzheimer’s and traumatic brain injuries, can be improved with light therapy. What does neurology have to do with light? And even if I understand that light can and does alter the skin, why (how?) would it reduce wrinkles or acne?

I remember from my brief, failed attempt at becoming a millennial plant parent that houseplants respond to sunlight more dramatically than I might’ve guessed; the cheery, perky pothos I bought for my desk drooped within two days because I’d placed it too far from a window. But that’s a plant. I am not a plant.

(Am I a plant?)

Photo: Elizaveta Porodina

Light-therapy devices use different kinds of light, from invisible, near-infrared light through the visible-light spectrum (red, orange, yellow, green, and blue), stopping before the harmful ultraviolet rays. So far, the effects of red and near-infrared light are the most studied; red light is often used to treat skin conditions, whereas near infrared can penetrate much deeper, working its way through skin and bone and even into the brain. Blue light is thought to be especially good at treating infections and is often used for acne. The effects of green and yellow light are less understood, but green might improve hyperpigmentation, and yellow might reduce photoaging.

The concept of using sunlight or visible light (in other words, colors) to cure diseases is an old one, something humans have intuited again and again across the centuries. In the late 1800s, European doctors began recommending heliotherapy for various illnesses, including tuberculosis; it was thought that sunlight could destroy the disease-causing bacteria. Avicenna, a Persian physician who practiced ca. A.D. 1025, thought color itself could treat various ailments — red was for stimulating blood flow, blue was for cooling the body, yellow was for easing muscle pain. He also believed a person with a nosebleed should not so much as look at the color red, as it would make the bleeding worse.

The modern study of light therapy arguably began in the 1960s, but it got a significant boost in the late 1980s, when NASA scientists started experimenting with light-emitting diodes, or LEDs, to stimulate plant growth in the hope that, one day, astronauts would be able to grow their own food while in deep space. It’s now almost taken for granted that they can — and they do — grow produce like lettuce, kale, and cabbage in 40ish-pound rectangular boxes that emit a purple-pink glow. (Plants absorb red and blue light and reflect green light, which creates the magenta effect.) On Valentine’s Day 2016, the astronaut Scott Kelly posted a photo from the International Space Station: The background is Earth, and the foreground is a bouquet of space flowers — zinnias grown onboard.

Kelly had revived the zinnias after a bout of mold; space travel does weird things to flowers. It does weird things to the human body, too. In space, even the smallest scratches don’t heal properly on their own. It’s not fully understood why, but, as the theory goes, the zero-gravity environment disrupts the cellular and molecular processes involved in tissue repair. But something funny happened to the scientists who were growing the plants under the LEDs: The cuts on their hands healed, almost as they would on Earth. This accidental discovery helped drive interest in the search for a medical application of light, says Janis Eells, who studies light therapy at the University of Wisconsin–Milwaukee. (Eells began her career in pharmacology but switched to studying photomedicine after being amazed by its healing potential. “Light is my new drug,” she told me.) Some scientists who study photomedicine believe the NASA origin story is overblown, that it’s only one of the factors that led to the development of the field. “People sure do like to talk about it,” said Michael Hamblin, a former principal investigator at the Wellman Center for Photomedicine at Massachusetts General Hospital.

Well, of course we like to talk about it! I like to talk about it now, ever since I started using these devices. They are futuristic, otherworldly; it makes perfect sense to think this technology might’ve come from outer space. My Joovv Mini is an 8¾-by-15-inch flat panel of red and near-infrared lights, and it costs $695. I tend to turn it on after dark, when the lights cast an eerie red glow in my living room that makes me think of the Stranger Things logo. Mine is small enough to keep on a side table, and it’s meant for “targeted treatments”: face, joints, or muscles, one at a time. But there are bigger versions, too, intended to be used on your whole body at once — the biggest Joovv device is the Elite, which is 26¼ by 72 inches and costs $5,995. You’re supposed to stand in front of the larger ones, but some other at-home products can be configured in dome shapes, like the Celluma Pro (an LED device on loan to me from aesthetician Joanna Czech), so you can lie underneath, maybe take a nap. I also tried the Déesse Pro LED Mask (lent to me by aesthetician Shani Darden), the same type of device Chrissy Teigen and Jessica Alba have shared photos of themselves wearing. With the mask, you can, in theory, multitask, which is maybe why I liked it the least.

I expected these things to be hot to the touch, but they’re not; they’re room temperature, maybe even a little cool. Yet after a few minutes of sitting in front of them, I feel warm: It’s my cells, apparently, heating me from the inside out. I’m growing attached to the blissed-out sensation I get from the red glow. It’s similar to the sun-drunk feeling I remember as a California teenager, minus the guilt I now associate with damaging my skin. I’m not sure if it’s “working,” but I’m also not sure that it isn’t. Since the summer, I’ve had two small scars just above my right wrist, accidental tattoos from making dinner. It might be my imagination, but once a day for a week now, I’ve been putting my hand under the Celluma Pro panel, and I think the scars are fading finally.

But how? Why? Sometimes, trying to understand photobiomodulation is so circular it makes me think of an exasperated Luke Wilson in Idiocracy trying to understand the energy drink Brawndo. (What are electrolytes? It’s what they use to make Brawndo. But why do they use it to make Brawndo? ’Cause Brawndo’s got electrolytes.) Researchers who study light therapy say the mechanism at work here isn’t 100 percent clear, but basically, light sparks a cellular response because … our cells respond to light.

For red and near-infrared light, scientists speculate that the light interacts with something called cytochrome c oxidase, or CCO, a photosensitive enzyme found within the mitochondria. Eells thinks of it as light giving the mitochondria a little kick in the pants. “I’m not sure the mitochondria are real happy to get that zap of red light,” she said. “But what it does is it tells the cell to start making the proteins that will protect it or that will make it healthier.” When CCO finds light, it converts it to energy and uses that energy to do whatever that cell is supposed to do, only more efficiently. “We have all these damn creams we try to rub on our face, and this lets your cells do it naturally,” she said.

It turns out mitochondria and chloroplasts in plants are “basically evolutionary kissing cousins,” as Eells phrases it. Chloroplasts absorb light and make energy for plants during photosynthesis; our mitochondria convert light to energy in a similar way. I am a plant, sort of, or at least my cells behave more like plants than I would ever have imagined.

Photo: Elizaveta Porodina

Close up, light therapy is complicated, baffling, impenetrable. Take a few steps back, though, and it’s about the most obvious idea on earth. In a way, light therapy has been a reminder of how often I overlook the basics, how every few days I need to force-feed myself similar reminders about how to be a human: Water is good, sleep is good, socializing with friends is good, alcohol is not always so good. Light is good.

Still, there are a few claims about light therapy I know not to fall for. Any at-home device that makes confident promises about green or yellow light is to be met with skepticism; the evidence just isn’t there yet. Pulsing red light, a hypnotizing effect some devices offer, should be regarded with interest mixed with some suspicion. (Dr. Jared Jagdeo, director of the Center for Photomedicine at SUNY Downstate Medical Center, told me firmly of pulsing red light, “Nobody knows the function of that. Anyone who claims to know the function of it, they’re just hypothesizing.”) Anything cheaper than a few hundred dollars is probably ineffective, and prescribing yourself light therapy for some ailment instead of visiting a doctor is inadvisable. The scientists who’ve studied photomedicine for decades met my questions with excitement and trepidation; many of them fear the consumer appetite will outpace the science, as tends to happen with wellness fads.

It does make sense that light therapy is gaining traction as a wellness practice. It fits right in with the paleo diet, biphasic sleep, and other theories that assume what is modern is bad and what is ancient (and therefore natural) is best. Not that these theories are necessarily wrong. In a viral 2014 interview with the website Into the Gloss, the actress Shailene Woodley shared her beliefs about the link between vaginal health and the natural light of the sun. “If you live in a place that has heavy winters,” she said, “when the sun finally comes out, spread your legs and get some sunshine.” Yeast infections in particular, she explained, are no match for sunlight. She was wrong about the way it works (she assumed it involved vitamin D), but she was right that it does work, or at least that it can: There is some evidence that blue light can destroy fungi like Candida albicans, which can cause yeast infections.

The rise of light therapy also happens to coincide with increasing paranoia around climate change and real anxieties over whether we’ll eventually live in a world where it isn’t safe to be outside for very long. In California this past fall, smoke and dust storms from the relentless wildfires caused “fine particulate matter,” which has been linked to heart disease, lung disease, and premature death, to settle in the air. People living in the North and East Bay were advised to stay inside; my parents had just moved to Napa Valley, and they sent me photos of the neighborhood haze. I think about this now and a vague image comes to mind of a future set even more indoors, me curling up around my Joovv Mini, soaking up artificial light like a space-station zinnia.

At-Home LED Devices

Photo: Courtesy of the vendor
Photo: Courtesy of the vendor
Photo: Courtesy of the vendor

*This article appears in the March 2, 2020, issue of New York Magazine. Subscribe Now!

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‘Light Is My New Drug’