LED photomodulation: light for the skin!

Light to rejuvenate, heal or relieve? Yes, the benefits of light waves have been known to doctors since the 1950s, but it wasn't until the early 2000s that NASA's advances in accelerating wound healing in zero gravity led to the indirect discovery of the anti-aging properties of light. LED photobiomodulation. Since then, scientific studies have constantly revealed new medical and aesthetic virtues. This technology is now available to the general public in the form of LED masks or LED headphones for everyday use. So how does LED therapy work and what are its benefits for the skin? What is the value of at-home devices, and what specific features do they need to have to guarantee results? Whether yellow, blue, green or red, electroluminescent light has not finished illuminating your face.

What is LED photomodulation?

LED photobiomodulation is a technology that diffuses the energy of cold, artificial, electrically generated light into the various layers of the skin and other tissues. Depending on the chosen color and therefore wavelength, the energy of the light beam emitted by LEDs (Light Emitting Diodes) enhances cellular activity. Exposure to these light-emitting diodes serves a number of purposes:

• in sports medicine to reduce inflammation and pain and improve muscle recovery;
• in oncology to reduce the side effects of radiotherapy and chemotherapy;
• in neurology to relieve pain associated with neurodegenerative diseases;
• in dermatology and aesthetic medicine to correct and repair a number of skin pathologies and traumas, such as accelerating wound healing, treating photoaging and actinic keratosis, and providing facial photorejuvenation; 
• at home as a skincare tool to promote hair and nail regrowth, even out skin tone, limit acne blemishes, firm skin and reduce wrinkles.

This painless technique can be used in all seasons, and complements or boosts other aesthetic or cosmetic treatments. The LED device, often in the form of a mask, is applied a few centimetres from the face for between one and 45 minutes on cleansed, make-up-free skin.

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How does LED photobiomodulation work?

A little physics to understand how LED phototherapy works

Let's get back to basics. Visible or invisible light is a wave, which means it moves, or more precisely, it oscillates. This movement is created by the billions of excited particles that make it up: called photons. As they move, they create and move energy that can be absorbed by your skin.

This light is broken down into several light rays, each characterized by a wavelength. Wavelength is a physical quantity that allows you to distinguish families of light rays on the electromagnetic spectrum. To sum up, there are three main categories of rays.

• Ultraviolet light, abbreviated U.V. It is invisible to the eye, and ranges from 10 to 400 nm. They make us tan and synthesize vitamin D, but are also responsible for melanoma;
• Visible light, detected by the human eye and made up of the colors of the rainbow, lies between 400 and 700 nm. This is where some of the LED photomodulation wavelengths are found.
• Infrared A (also invisible) is found between wavelengths of 700 nm and 1,000 nm, and is capable of stimulating the matrix of the deep dermis.

These rays all come from sunlight, but can be reproduced by electrical devices. And in our case by photomodulation devices such as LED masks for the home or more powerful devices for professionals. Currently, there are many medical devices on the market, broadcasting wavelengths ranging from 247 to 1,300 nm, but only certain bands have revealed benefits for our bodies and our skin.

The higher the wavelength, the deeper the light beam will penetrate the layers of our skin (epidermis, mid or deep dermis).

Biological and biophysical mechanisms of LED phototherapy

The mechanism is not fully understood, but this light energy is thought to act at the molecular level, and more specifically on cellular respiration and the production of adenosine and ATP, the fuels of all living cells. 

Simply put, the light wave created by LEDs penetrates your skin with its energy. Certain elements of the epidermis and dermis are able to absorb this energy. These are chromophores such as melanin, hemoglobin and opsin.  

The energy is then metabolized by the skin cell, causing chemical changes and improving its functioning to reduce symptoms or discomfort. Cells are recharged with energy. The result is improved proliferation and cell renewal.

While visible red and near-infrared wavelengths are the most widely recognized and favored in the practice, recent scientific studies reveal the value of other visible light waves. 

•  Blue light around 415 nm only penetrates the epidermis. It is mainly used to combat the bacteria responsible for acne. It is recognized for its anti-bacterial, anti-viral (herpes virus) and anti-inflammatory properties. However, the use of this light wave is controversial. Indeed, according to some scientists, the boundary between UV and blue light between 400 and 500 nm is ill-defined. What's more, like ultraviolet rays, it is accused, over the long term, of creating earlier and more stubborn hyperpigmented areas on darker, matte skins.
• Yellow light around 585 nanometers, would act on hyperpigmented areas by directly suppressing melanin content, according to a 2018 in-vitro study carried out on epidermal melanocytes (pigmentation cells).
• Green light from (495 nm to 570 nm), according to some experiments, is beneficial for improving cellulite and tissue swelling. However, this therapeutic window still requires a great deal of study.
• Red light at 633 nm and near infrared at 830 nm are the rays that penetrate deepest, right down to the dermis. These two wavelengths have been the subject of numerous scientific studies, and their effects on photorejuvenation and healing are proven and highly appreciated. They boost fibroblast activity and thus collagen and elastin production. They are also useful for baldness treatments or for facilitating the penetration of mesotherapy products.

Focus on the benefits of red and near-infrared light in photobiomodulation

A June 2021 in vivo study carried out on human fibroblasts suggests that red and near-infrared light radiation promotes the expression of certain genes and stimulates the synthesis of type 1 and 3 collagen precursors and elastin. 

They are therefore recommended for correcting the signs of natural aging and repairing tissues traumatized by UV rays or other pathologies. 

• Red light smoothes wrinkles and fine lines, densifies the dermis and improves tissue tone. 
• It accelerates and improves wound healing.
• Anti-inflammatory, it can reduce chronic redness, but also acne and rosacea, and improves the resistance of sensitive skin to stimuli.
• In conjunction with drugs that make the skin more receptive to red light, it treats certain cancers.
• Helmet-shaped devices can improve baldness.

Clinically, there are two specific wavelengths for inducing the photobiomodulation effects of red and near-infrared light: 633 and 830 nm.

Features to check before you invest  

Equipment used in dermatology or aesthetic medicine practices will inevitably be more powerful and deliver more advanced results, as sessions are supervised by health professionals. Expect to pay between 30 and 80 euros per session, ranging from 15 to 45 minutes, depending on the areas to be treated and the level of concern. Packages for ten sessions (up to several hundred euros) are also available. So it's natural to want to invest in home devices. Even if the results are a little less effective, they are more than capable of sustaining the effects of your treatment over the long term, or achieving a certain degree of tissue rejuvenation. On the market, prices vary enormously, from around a hundred euros to 1,000 euros in some cases. So if you don't have the time to use this device for several minutes a week, you'd better pass, as the effects are proportional to the frequency of use. By the way, let me know in the comments if you'd like some device references.

On average, you should expect to pay between 300 and 1000 euros for good value for money. 

Here's what you need to check before investing.

• The wavelength emitted by your device. For red and near-infrared light, studies show a specific wavelength, not a range. So your equipment must specifically emit a wavelength of 630 nm and 830 nm to enjoy the benefits of red and near-infrared light. A lack of specificity can also mean a lack of efficacy.
• The price of the device. Diodes emitting specific wavelengths have a higher production cost, so your device will be relatively expensive.
• The right wavelength alone is not enough. Irradiation, i.e. intensity, measured in milliwatts/cm2, is just as important. This is the amount of energy that strikes the skin per square cm per second. You need a sufficient quantity, and fast enough, to provoke a biological response.

Devices recognized as clinically effective offer ranges between 40 and 100 mW/cm². Please note that these values do not refer solely to the device, but to the ability of each diode to deliver the right amount of light. It's also important to consider the distance of the diodes from your face. Either this information is published on the brand's website, or you need to contact the seller, as this is a key parameter not to be forgotten.

• The frequency of use recommended by the vendor. It should be adapted to your lifestyle. If you have children or a busy job, you won't have time to use your device for 30 minutes or even an hour a day. The higher the irradiance, the shorter the operating time.

For the same reasons, it's normal to be able to move around during your light therapy session. Ideally, it should be battery-powered, lightweight and comfortable.

Discussions and fears about phototherapy equipment

There's a lot of discussion about this type of device, which is accused of prematurely melting facial fat through heat emission. This is just a misunderstanding. While this may be the case with radiofrequency, ultrasound or lasers, it is not the case with LEDs. This so-called cold light does not generate heat in tissues, nor does it traumatize them. These light beams do not target fat tissue, so there is no risk of premature fat loss. 

On the other hand, people suffering from certain dermatological pathologies linked to hypersensitivity to sunlight should not use this equipment. In fact, solar urticaria, lupus erythematosus of the stomach and chronic actinic dermatitis are favored by exposure to the sun. Sunlight is made up of red, green, blue and yellow light waves. Theoretically, therefore, these people can develop these diseases following an LED session. Even if most of these problems are caused by UV or blue light, it's best to be accompanied by a professional to make sure that LED therapy is right for your skin.

Please note that there are no scientific reports of any side effects from red light or near-infrared light. 

Home devices also ensure efficiency and safety, but it's vital to follow the manufacturer's instructions for use. 

So, if you buy a face mask, don't use it on your hands or arms, as the thickness of your skin is not the same. The device is calibrated according to your tissue density. 

Eyes should be protected by special glasses in the office. For at-home devices, follow the recommendations. 

This is good news for pregnant and breast-feeding women, who are obliged to adapt most of their beauty routines during this period to protect their babies, LED masks present no danger. 

Although many scientific studies remain to be carried out to better understand the biological mechanisms of photobiomodulation, this effective, pain-free and safe method is not about to disappear. Popular with patients and skincare fans alike, at-home LED light and cosmetics are an ideal tandem for maintaining the beauty of your skin. The rays of light soothe the discomforts of the day, prepare the skin for further treatment and provide an in-depth treatment tailored to your skin concerns. If you've already tried this type of device, please share your experience!

Sources :

Low-level red plus near infrared lights combination induces expressions of collagen and elastin in human skin in vitro - PubMed (nih.gov)

Differential response of human dermal fibroblast subpopulations to visible and near-infrared light: Potential of photobiomodulation for addressing cutaneous conditions - PubMed (nih.gov)

Combined 633-nm and 830-nm led treatment of photoaging skin - PubMed (nih.gov)

Under the spotlight: mechanisms of photobiomodulation concentrating on blue and green light - PubMed (nih.gov)