What is red light therapy and photobiomodulation (PBM)
Red light therapy, often referred to as photobiomodulation (PBM), is a form of light therapy in which specific wavelengths of red and near-infrared light are used to influence biological processes in the body. In contrast to heat treatment or cosmetic light, PBM is about how light energy is absorbed by the cells and acts as a biological signal that can support the body's own regulation and repair processes. The technology has been used for several decades in research, rehabilitation and clinical practice, and is today available for both professional use and home use. PBM primarily uses red light in the area approx. 620–700 nm and near-infrared light in the range approx. 780–1,060 nm. These wavelengths can penetrate skin and underlying tissue without damaging cells or tissue when used correctly.
Scientific consensus and clinical guidelines for photobiomodulation (PBM)
In recent years, photobiomodulation has gone from being a research field with individual studies to an area where there are now systematic overviews, consensus articles and clinical guidelines. International panels of experts have reviewed hundreds of studies to assess both the safety and effectiveness of using red and near-infrared light. These reviews indicate that PBM is a non-ionizing, tissue-friendly technology with documented biological efficacy when appropriate wavelengths, doses and protocols are used. At the same time, it is emphasized that PBM is not one universal treatment, but a method whose effect depends on precise technical design and correct use.
How red light therapy works in the body – biology and physics
When red or near-infrared light hits the body, the photons are absorbed by light-sensitive structures in the cells. The best-known mechanism is linked to the mitochondria, the cells' energy-producing organelles. Here, the enzyme cytochrome c-oxidase plays a key role in the electron transport chain and in the production of ATP, which is the cells' primary energy carrier.
Light absorption can contribute to more efficient electron transport in the mitochondria, better energy availability in the cells, improved utilization of oxygen and modulation of nitric oxide (NO). Nitric oxide is involved in cell communication and can indirectly support blood circulation. Red light therapy does not add energy in the same way as heat, but modulates biological signals, which is why the term photobiomodulation is used - light as a biological regulator.
Photobiomodulation as a biophysical signal, not heat or "energy" in the vague sense
Photobiomodulation is often wrongly described as pure heat treatment. In reality, PBM is about light that functions as a biological signal. When red and near-infrared light is absorbed in tissues, particularly in the mitochondria's cytochrome c oxidase, this can affect the cells' energy metabolism, redox balance and signaling pathways. The effect occurs before a significant increase in temperature, which clearly distinguishes PBM from both sauna, IR heat and other thermal methods. This is also the reason why PBM can be used purposefully in clinical contexts where heat alone is not desirable.
What is red light therapy used for in practice
Pain and muscle recovery
Red light therapy is often used in connection with muscle tension, stiffness and recovery after physical exertion. Many people find that light therapy can support the body's natural repair processes in muscles and connective tissue, especially with regular use over time.
Joints and connective tissue
For load-related challenges in joints and tendons, PBM is often used as a supplement to other follow-up. Near-infrared light can penetrate deeper into the tissue and reach structures around joints and connective tissue.
Skin, scars and aging
Red light is widely used in skin care and aesthetics. The use is linked to support of the skin's own renewal process and the influence of collagen and elastin structures. Red light therapy is therefore often included in programs for skin quality and recovery after skin treatments.
Sleep, circadian rhythm and recovery
Light affects the body's biological rhythms. Red light therapy can be used in the evening without disturbing melatonin production as blue light can do, and many people use red light as support for relaxation and recovery.
Inflammation and stress load
PBM is often used to support the body's balance during prolonged physical or mental stress. The focus is not on treating disease, but on supporting normal biological processes and well-being.
Red light, near-infrared light and full spectrum
Red light and near-infrared light work at different depths in the tissue. Red light is absorbed more superficially and is often used for skin and surface tissue, while near-infrared light penetrates deeper and can reach muscles, joints and connective tissue. Many modern systems combine multiple wavelengths to provide a broader biological response, often referred to as full-spectrum red light therapy.
LED versus laser in red light therapy
Both LED and laser are used in photobiomodulation, but have different properties. Lasers provide highly focused light with high precision and are often used in clinical contexts. LED-based red light therapy provides more diffused light that covers larger areas, which makes the technology well suited for home use and full-body treatment. Effect is not only about strength, but about the right wavelength, dosage, distance and treatment time.
Dosage, irradiance and why more light does not always produce a better effect
A key insight from PBM research is the existence of a therapeutic window. Too low a dose produces no biological response, while too high a dose can reduce or cancel the effect. Parameters such as power density (mW/cm²), amount of energy (J/cm²), treatment time and distance to the light source are decisive. Professional PBM systems are therefore designed for stable and controllable light delivery, while simpler solutions often provide greater variation in actual dose. This is an important distinction between medically-oriented PBM and general wellness use.
The difference between LED-based PBM and laser-based PBM
Photobiomodulation can be delivered with both laser and LED. Lasers provide coherent light with high precision and are often used in medical settings for small, defined areas. LED-based PBM provides non-coherent light, but can cover larger surfaces and is currently the most widely used technology for whole-body and systemic PBM. Modern professional LED systems can deliver high and even irradiance without the safety challenges that come with lasers, which makes them suitable both in clinics and for advanced home use.
Home use, clinical use and regulatory role understanding
It is crucial to distinguish between PBM used as a wellness and recovery measure, and PBM used as part of medical or clinical treatment. In Norway and the EU, medical equipment is strictly regulated, and the manufacturer's intended use determines which requirements apply. Serious operators therefore clearly communicate what the equipment is intended for, and avoid medical claims where documentation and approval are not available. For users and clinics, this provides safer choices and more realistic expectations.
Home use versus clinical use
Red light therapy can be used both at home and in professional environments. Home equipment is developed for regular use with adapted intensity, while clinical equipment offers higher precision and more adjustment possibilities. The choice depends on needs, experience and desired area of use. Many choose home use as a long-term supplement in a holistic lifestyle.
How to choose the right red light therapy
When choosing red light therapy, it is important to look at which wavelengths are used, whether the system combines red and near-infrared light, effect per area and not just total wattage, and whether the solution is adapted to point treatment, larger areas or whole-body use. Quality, safety and documentation are decisive factors. The right choice is about biology and physics, not marketing.
Frequently asked questions about red light therapy
How often can red light therapy be used? Many people use red light therapy several times a week, and some daily, depending on the intensity and area of use.
Is red light therapy safe? Used correctly and according to the manufacturer's guidelines, PBM is considered a non-invasive and gentle technology.
How quickly do you notice the effect? The experience varies. Some notice changes quickly, while others experience a gradual effect over time.
Can red light therapy be combined with other technologies? Yes, many people combine PBM with other forms of light, recovery, movement and lifestyle measures.
Summary
Red light therapy and photobiomodulation are based on well-known biophysical principles where light is used as a signal to the cells. The technology combines modern physics with the body's own biological mechanisms and is used today both in professional environments and at home. For many, PBM is a long-term tool for supporting energy, recovery and balance in the body.
Conclusion – About Uno Vita's editorial staff
This article has been prepared by Uno Vita's specialist editorial team with the aim of providing a sober, up-to-date and professionally based review of photobiomodulation and red light therapy. Uno Vita works with proven technologies in light, electromedicine and biophysical support, and emphasizes quality, transparency and correct use. The content is intended as general information and cannot replace medical assessment or treatment. Freedom of expression and free access to scientific knowledge are fundamental principles for our work.
