Red light therapy (RLT) is a type of treatment provided in clinical and cosmetic settings that incorporates red light to improve the skin’s appearance, such as reducing fine wrinkles, scars, redness and acne. It is also used in the medical setting to help reduce pain and increase healing in the joints, such as tendinitis, sprains/strains, and arthritis.
Red Light Therapy is also known as:
- Phototherapy
- Photodynamic therapy
- Photobiomodulation
- Low-level laser light therapy*
- Low-power laser therapy*
- Cold laser therapy*
- Biostimulation
- Photonic stimulation
*this is a misnomer, because red light therapy does not use laser energy.
Interest in red light therapy emerged decades ago when NASA conducted experiments on growing plants in space and healing injuries to astronauts. Results of this research pointed to a connection between red light and positive, biological effects on human tissues. This ability of light (photons) to alter biological activity in living cells is called photobiomodulation and is the means by which RLT achieves therapeutic benefit.
What is Light?
Understanding this requires some basic knowledge of how the eye works, and physics.
First of all, vision is possible only in the presence of light. This means light must bounce off objects in your visual field and enter your eye, which then “translates” the bounced light into an image that is perceived by your brain.
But how do we perceive color? White light is actually made up of wave energy that propagates in multiple wavelengths. It is this difference in wavelengths, the molecular properties of all objects, and the design of the human eye’s retina that creates the perception of color. Objects that appear a certain color reflect the wavelength of just that color into your eye and absorb all other wavelengths. For example, a red shirt reflects the red wavelengths and absorbs the blue, orange and yellow wavelengths. Altogether, these component wavelengths of white light is called the visible spectrum of the electromagnetic spectrum, which is shown here:
Electromagnetic energy exists as an electrical field with a magnetic field 90 degrees to its axis and propagates at the speed of light. The electromagnetic spectrum is the range, in wavelengths, of electromagnetic energy existing in nature, from the very tiny wavelength gamma ray (.0001 billionth of a meter) to the very long wavelength of AM radio (100 meters). Light is in between these extremes and is the only EM waves humans can see, between the wavelengths of about 380 to 700 nanometers (nm, billionths of a meter).
When light passes through a crystal prism, it bends. Since light is made up of different wavelengths, the component EM waves of white light behave differently (bend at different angles and speeds) as they enter the prism and can now be visually distinguished from one another as separate colors in a band: red, orange, yellow, green, blue, indigo, violet. Similarly, rainbows form when suspended rain droplets bend the sun’s light and separate it into its component colors.
RED light is the longest wavelength of visible light, while VIOLET is the shortest. As the electromagnetic wavelength increases, the frequency (the number of times the wavelength passes a fixed point, measured in hertz – Hz) decreases, and so does the amount of energy it carries. So, the very small wavelength/high frequency gamma and x-rays carry a lot of energy and are dangerous to tissues. You may have heard that ultraviolet (UV) light can cause skin cancer. This is because much of its energy is absorbed by the skin, where it does damage to cells. Red light, being the longest wavelength of light, doesn’t have the energy level of UV and therefore does not pose danger to tissue; in fact, as we will discuss later, it has beneficial effects to tissues.
How Does Red Light Therapy Work?
Red light therapy is used to:
- Improve wound healing
- Reduce pain in joints
- Treat tendonitis
- Reduce headaches
- Reduce stretch marks
- Reduce wrinkles, fine lines and age spots
- Improve psoriasis, rosacea and eczema.
- Improve appearance of recent scars
- Improve hair growth in people
- Improve acne
It’s well established that light can initiate biological change in living organisms. Perhaps the most well-known is photosynthesis, the series of biochemical reactions where sunlight energy catalyzes the formation of sugar (glucose molecules) in plants. Photons from light get absorbed by tiny structures in a plant called chloroplasts, which provide the biological machinery to synthesize glucose (basically, stored energy) from inorganic carbon dioxide and water.
Another example of light effecting change in living tissue is vitamin D formation, where the pre-cursor of vitamin D is created when UVB light strikes 7-dehydrocholesterol molecules in the skin
With red light, the pathway is likely similar. Many research studies have been conducted over the years to uncover the mechanism behind red light photobiomodulation; i.e. the nature of its therapeutic effects. What is definitely known is that the red light wavelength (in the 660-700 nm wavelength range) tends to get absorbed in the nucleus and mitochondria of cells, in locations called chromophores. Mitochondria (image below) are the structures where energy is generated for the cell, much like the previously mentioned chloroplasts in plant cells. The nucleus contains the DNA, which is the template for protein synthesis.
We also know that photons can “excite” electrons – the tiny charges that orbit atomic nuclei. Cells and all their parts including the mitochondria are of course made up atoms. An “excited” electron means a movement of an electron to a higher energy orbit (further from/ less attracted to the nucleus).
In short, red light stimulation increases the energy state of electrons in sick tissues, enabling faster/enhanced reaction between adjacent molecules, as electron interactions between atoms are the basis of all biochemical reactions. This may translate into the cell “speeding up” its activities, particularly respiration (ATP formation from glucose via the Krebs cycle, i.e. energy production) as well as waste elimination and gas exchange. Redox signaling is the term used to describe this activity, and is the leading hypothesis for the mechanism of red light photobiomodulation.
With enhanced cellular signaling:
- If the cell is a fibroblast, it could lead to faster wound healing, as fibroblasts migrate to the injury/damaged site to synthesize and lay down collagen fibers.
- If the cell is a stem cell (undifferentiated cell), it could enhance the transformation of stem cells to fibroblasts or chondrocytes, which make collagen and cartilage, respectively.
- If the cell is an epidermal cell, it could mean faster cell turnover to clear out abnormal cells in skin conditions such as eczema and psoriasis.
Cells are programmed to respond to specific extracellular signal molecules for development, tissue repair, immunity, and homeostasis. Errors in signaling interactions may lead to diseases such as cancer, autoimmunity (such as rheumatoid arthritis), and diabetes. Given this, it is feasible to assume that if red light therapy can enhance cell signaling, it can benefit these cellular functions and support tissue healing and pain reduction.
Red Light Therapy is Shown to Reduce Inflammation
Many studies found that red light reduced inflammation in tissues. Inflammation is the body’s response to injury or some kind of irritant and is characterized by redness, swelling, and pain. It involves a complex series of steps involving multiple protein clotting factors in the blood and tissues.
Inflammation also involves several types of cells involved in the reparative process, including macrophages (“cleaner” cells that remove debris), basophils (a type of white blood cell that secretes histamine and heparin to make blood vessels more leaky and manage clotting), and fibroblasts. It also involves cytokines—chemical signaling molecules that cells use to communicate and coordinate activities within themselves and with each other.
Inflammation often gets out of hand at the injury/ damaged tissue site and contributes to the problem by increasing pain and delaying healing. In fact, diseases like arthritis, irritable bowel syndrome, vascular disease, diabetes, and even Alzheimer’s disease involve chronic (ongoing) inflammation. This is the basis for the utilization of anti-inflammatory medications such as steroids and non-steroidal medications (NSAIDs) like Tylenol and Ibuprofen for inflammation.
The inflammation-reducing ability of red light therapy is likely due to its ability to enhance cell signaling and molecular flow in the cell. One study notes that overall reduction in inflammation is one of the most reproducible effects of photobiomodulation [from red light]. This is particularly important for inflammatory diseases affecting joints; acute trauma, lung disorders, and brain injuries resulting in inflammation.
Another proposed model to explain how light therapy works is photon-mediated ion channels in cell membranes (image below). Basically, ion channels are the passageways in membranes (think tiny gated doors) where ions flow through, which require energy to open. An electrical gradient is formed as the ion concentration differs on either side of the membrane, and this gradient can be used to drive movement of molecules into and out of the cell, very much like voltage. In fact, this is how neurons produce nerve impulses. Red light photons may be able to activate these ion channels, thereby boosting efficiency of ion flow and helping the cell maintain equilibrium.
Should You Try Red Light Therapy for Arthritis?
Given its photobiomodulation ability, red light can be a useful, self-administered treatment for skin conditions and tissue injury/pain. It has powerful effects of improving cellular function to diseased/ injured tissues, which can improve recovery and healing. Being lower frequency, it is not harmful to the body, unlike UV light.
However, red light therapy should not be considered a “magic bullet” for “curing” things. Every person is different, and if you have complicating factors in your health and/or your condition is advanced, it may not work as well. While the human body has remarkable regenerative and healing abilities, there are limitations.
For example, in the case of advanced degenerative osteoarthritis of the knee or hip, much of the cartilage has worn away, and there are multiple areas of exposed bone. Normal, healthy cartilage that lines joint surfaces is smooth and resilient to pressure. Unlike the epidermis (skin), it does not regenerate very well, so if you lose quite a bit of it or tear it, it cannot regrow back to normal.
But, if you are at the very early stages of osteoarthritis, red light therapy can be very helpful in arresting its progression. Arthritis usually appears mid-age, but if you engaged in heavy contact or heavy impact sports such as football and gymnastics, it may start earlier. What happens is tiny disruptions in the cartilage start to gradually separate, much like how a tiny crack in your windshield “grows” in length as your car absorbs shock from the road each time you drive. These tiny separations then form pits in the cartilage, which widen. Bone is exposed, inflammation sets in, and you’re on your way to an eventual knee or hip replacement some years later. But if you apply red light therapy to the tiny disruptions as they form, there is a much better chance of arresting their progression by stimulating cartilage growth. The red light will energize chondrocytes, the dormant cells embedded in the cartilage matrix tasked with maintaining it, and can stimulate the proliferation of chondroblasts, the cells that secrete collagen matrix.
You can still apply red light to an advanced osteoarthritic knee for palliative purposes, since red light can suppress inflammation and therefore provide some degree of pain relief. If doing so allows you to stay on your feet a couple more hours in a day, then that is definitely a positive benefit to your quality of life.
A good solution for applying red light therapy to the knee is the 120 LED wrap. It is a flexible pad containing 120 light emitting diodes (LEDs) with each diode containing one (1) 660 nm red light emitter and two (2) 850 nm infrared emitters. You wrap it around your knee and hold it in place with an elastic band that comes with it, and press a button.
Alternatively, if you are patient, you can use a red light torch device. This requires you to hold it in place for a couple of minutes. The good thing about the torch is that you can target small areas. For example, if you know you have a cartilage tear on the inside of your knee joint, you can press the torch over it and concentrate the light on that one spot. The torch is also good for small joints; i.e. knuckles.
As always, when you self-treat conditions use a multi-pronged approach: improve your diet, get enough rest, drink enough water every day (sometimes not easy to remember!), avoid ingesting toxins as best you can (nix smoking, alcohol, processed food, excessive pollution); get fresh, clean air by walking where there are lots of trees; exercise/ move often to strengthen your muscles and heart, and avoid negative thinking, which elevates stress hormones. Do all these things consistently and you can rest assured that you are giving your body its best chances for recovering from disease and pain.
