Author: Therabody Scientists: Tim Roberts, MSc; Kyle Silvey, PhD; Michelle Darian, MS, MPH, RD, LDN

Light therapy has gained popularity in recent years as a holistic approach to healthier skin at the cellular level and reducing the signs of aging. Not only does light therapy benefit the skin, its benefits can even include pain relief and muscle recovery. But is there scientific evidence to support this wellness practice? 

This article delves into the science behind three types of light therapy: red light, blue light, and infrared light therapy. Explore how each therapy works, the science-supported benefits of each type of light therapy, and when to use each. For detailed information on selecting a safe and efficient light therapy device, read on. 

What Is Light Therapy?

Light therapy, also known as phototherapy or photobiomodulation, is the intentional exposure to light at specific wavelengths. Different wavelengths of light are responsible for producing different colors — including red and blue light. Some wavelengths are invisible to the naked eye, for example; we can’t see infrared light alone. [1]

Different light wavelengths penetrate the skin at different depths. Generally, shorter wavelengths don’t penetrate the skin very deeply, while longer wavelengths can penetrate through skin tissue and can even make their way to the bone. [1]

Because different light wavelengths penetrate the skin at varying depths, wavelengths have independent benefits. Light therapy is responsible for a range of benefits; for example, it can reduce fine lines and wrinkles, reduce inflammatory acne, increase circulation, accelerate wound healing and tissue regeneration, reduce acute and chronic pain, and help restore normal cellular function. [1] 

How is Light Therapy Delivered?

Light therapy can be delivered in various ways, including through LEDs, LASERS, and broadband light. LED (light emitting diode) therapy is a popular skincare treatment that uses varying wavelengths of light, including red, blue, and infrared, to stimulate the skin and tissue beneath the skin’s surface. It’s critical to use devices that produce the appropriate and therapeutic dosages of wavelengths, which is fundamental to light therapy. More on this later. [2]

Let’s dive into the science behind red, blue, and infrared therapy to understand best how these wavelengths benefit the skin and body. 

What is Red Light Therapy?

Red light therapy, also known as low-level laser therapy (LLLT) or photobiomodulation therapy, uses a device that exposes the skin to red light. Red light therapy’s wavelength typically ranges from 620 to 750 nm. Red light is a longer wavelength, which can penetrate the skin tissue to produce therapeutic benefits. [3, 4]

How Does Red Light Therapy Work?

Think of light as a form of energy. Nearly every cell in the body, including on the skin, contains mitochondria, commonly referred to as the “master regulator of energy" for cells. Each cell’s mitochondria can consume red light and use it to create more energy. The increase in energy is then used for reparative cellular processes like tissue repair and cellular regeneration. [3, 4]

Red light therapy also stimulates procollagen synthesis, meaning it produces new collagen. [3] Collagen is a protein that serves as a building block for skin, muscles, bone, and other tissues in the body. It’s responsible for skin elasticity, making the skin appear more firm and youthful. The body produces less and less collagen throughout age, leading to sagging skin, fine lines, and wrinkles. Through its influence in stimulating collagen production, red light therapy can effectively reduce the appearance of fine lines and wrinkles and make skin appear firm. [5]

Benefits of Red Light Therapy

Red light therapy offers a spectrum of benefits, and scientists may have only scratched the surface of red light’s potential. Scientific research is currently underway to best understand how else it can be an effective treatment. [3, 4]

What is Blue Light Therapy?

Blue light therapy uses a part of the light spectrum — blue light — to achieve specific therapeutic effects. During blue light therapy, the skin is exposed to blue light, with a wavelength of about 415nm. This is considered a shorter wavelength light therapy, meaning it doesn’t penetrate deeply into the skin. However, blue light therapy can be a healing treatment on the skin’s surface. [6] 

How Does Blue Light Therapy Work?

Acne can form from bacteria that live on the skin. Blue light’s specific wavelength is absorbed by porphyrins, the compounds produced by the bacteria responsible for creating acne. When porphyrins absorb blue light, they release singlet oxygen molecules that kill the bacteria, effectively reducing acne. Studies show that blue light therapy is beneficial in reducing acne. [6]  

Benefits of Blue Light Therapy

A scientifically backed benefit of blue light therapy is its effectiveness in treating mild-to-moderate inflammatory acne on the skin’s surface. It can also improve skin conditions like blemishes. Blue light therapy can also be used as a proactive approach to acne management through its ability to control acne and improve the skin’s appearance without harsh chemicals or prescriptions. [6]  

What is Infrared Light Therapy?

Infrared light therapy is not visible to the naked eye, but you can feel it. This is the highest wavelength light therapy of the three types of light therapy, with a typical wavelength of 830 nm. Because infrared light has a long wavelength, it can penetrate below the skin’s surface even as deep as bone and muscle tissue. This allows infrared light therapy to offer a range of unique therapeutic benefits, from enhanced skin rejuvenation to muscle recovery. [5]

How Does Infrared Light Therapy Work?

Similar to red light therapy, infrared light is absorbed by cells and creates energy to be used for a host of therapeutic benefits. Due to its wavelength, infrared light penetrates deep into the body’s tissues, affecting cellular processes beyond the reach of visible light. [5]

Studies show that red and infrared light can accelerate wound healing and improve tissue strength in both normal and impaired tissues. These improvements in tissue strength are associated with increases in collagen synthesis and tissue collagen content. So, infrared light therapy can maximize muscle recovery when applied to muscles. [5]

Infrared light is responsible for the warm sensation you feel from the sun or a heat lamp. Similarly, infrared light therapy has a therapeutic warming effect. The warming of the skin can expand the blood vessels, also known as vasodilation. Blood can flow more easily through widened blood vessels, specifically on areas of the skin penetrated by infrared light. Increases in blood flow can reduce stiffness and soreness and even relieve pain. [7]

Because red and infrared light reaches different depths of the skin, light therapy devices often combine red and infrared light. This allows devices to provide comprehensive benefits to the skin and body, like skin rejuvenation and accelerated muscle recovery. [5]

Benefits of Infrared Light Therapy

Infrared light therapy offers numerous benefits. Here are examples of scientifically proven benefits of infrared light therapy: [5] 

Is Light Therapy Safe?

Light therapy is generally safe for most people. However, there are scenarios in which avoiding light therapy is recommended. Refrain from using light therapy after applying retinol. Consult with a dermatologist or medical professional before using light therapy in the presence of a skin condition, recent surgery, or dermatology procedure. 

When it comes to light therapy, the key is to select a treatment that is beneficial and efficient without becoming harmful, meaning it delivers the highest possible dose in the shortest amount of time without exceeding safety limits. 

Light therapy is designed to provide a therapeutic dose or fluence. The fluence can be thought of as the total amount of light energy delivered to the skin and is the result of the device’s power density for a specific treatment duration. Light therapy devices are designed to deliver the optimal fluence via a precisely controlled power density for a specific treatment duration in therapeutic and safe dosages. [8, 9] 

There are three points to be aware of: 

The therapeutic dosage can be calculated using the following formula: Dose (Fluence) = Power Density (mW/cm2) x Time (s) x 0.001

Here are examples of how to achieve therapeutic dosages and meet the above three criteria: [8]

Red light therapy: 

Blue light therapy: 

Red+Infrared light therapy: 

When Is The Best Time of Day to Use Light Therapy?

Aim to use light therapy in the morning to minimize its potential impact on sleep quality. Later on in the evening, typically after the sun has gone down, the body releases melatonin in response to darkness. Melatonin is responsible for making us feel sleepy and can help the body to relax and drift off to sleep. Light exposure reduces the amount of melatonin produced and can cause wakefulness, disrupting sleep. 

Studies investigating light therapy’s impact on melatonin and sleep outcomes report mixed results. Until the scientific consensus shows that light therapy does not disrupt sleep, it is recommended to use it earlier in the day. [10, 11, 12] 

How to Choose the Best Light Therapy Device

In order to select the best light therapy device for you, there are five main criteria to consider: 

With all changes to your wellness routine, discuss light therapy use with your dermatologist or healthcare provider to understand if it’s right for you. Light therapy devices are not intended for medical use and should never replace the care of a healthcare provider.

Key Takeaways

The benefits of red, blue, and infrared light therapy are backed by science, creating healthier skin at the cellular level and proven through clinical trials. The mechanisms behind light therapy may seem daunting, but remember, different wavelengths of light, red, blue, and infrared, offer unique benefits, from reducing fine lines and wrinkles to reducing signs of aging to acne treatment and muscle recovery. Whether you choose red, blue, or infrared light therapy, the evidence suggests that incorporating these treatments into your wellness routine can benefit you. 

References