Photobiomodulation (PBM) is the scientific process in which specific wavelengths of light activate biological changes in cells. Red light therapy and near-infrared therapy are applications of this principle. Contrary to what skeptics suggest, photobiomodulation is not an alternative medicine but an active area of research with more than 6,000 published clinical studies and a growing number of meta-analyses confirming clinically relevant effects.
The National Institutes of Health (NIH) in the US actively funds PBM research. NASA originally developed near-infrared light therapy for wound healing in astronauts in space capsules. These are not trivial origins.
The discovery: from laser science to LED therapy
The discovery of photobiomodulation is attributed to the Hungarian surgeon Endre Mester, who in 1967 experimented with laser radiation on mice and unexpectedly observed accelerated wound healing. He called the effect "laser biostimulation". Decades later, the same effects were demonstrated with non-coherent light (regular LEDs), opening the way to affordable applications outside the clinic.
The distinction is important: photobiomodulation does not work through heat (that is a different therapeutic mechanism), but through photochemical reactions in the cell.
The mechanism of action: what happens in the cell
The current scientific consensus, built on the work of Michael Hamblin (Harvard Medical School) and Tiina Karu (Russian Academy of Sciences), among others, describes the PBM mechanism in two main steps.
Step 1: Photon absorption by cytochrome c oxidase
Cytochrome c oxidase (CCO) is an enzyme in the mitochondrial respiratory chain. It absorbs photons in the wavelengths 620-700 nm (red light) and 750-950 nm (near infrared). With CCO activation:
- Increases the electron transport rate in the respiratory chain
- Increases the production of adenosine triphosphate (ATP), the energy currency of the cell
- Decreases production of reactive oxygen species (ROS) in stressed cells
- Improves mitochondrial membrane potential
ATP is essential for every cell that repairs, grows or adapts. In damaged or stressed tissue, ATP production is reduced; light activation restores this.
Step 2: Signaling cascades and gene expression
The primary photon absorption triggers secondary effects that go far beyond the mitochondria:
- Activation of the NF-κB signaling pathway, which modulates inflammatory responses
- Increased expression of growth factors (VEGF, TGF-β, FGF)
- Stimulation of nitric oxide (NO) production, which dilates blood vessels
- Activation of heat shock proteins, which repair damaged proteins
The result of these cascades is cell-specific, depending on the cell type and the degree of damage or stress. In healthy tissue the effects are minimal; they are greatest in damaged or stressed tissue. This explains why PBM has a therapeutic window: not every tissue always responds.
The Arndt-Schulz principle and dosage
One of the most misunderstood aspects of photobiomodulation is dosage. More light is not always better. PBM follows the Arndt-Schulz principle: low doses stimulate, high doses inhibit.
The optimal dosage is expressed in J/cm² (Joule per square centimeter) and depends on:
- Wavelength
- Target tissue depth
- Duration of treatment
- Power density (mW/cm²)
For skin treatment, the optimal dose is typically between 4-10 J/cm². For deeper tissue (muscle, joint) between 10-50 J/cm². Overdose (above 100 J/cm²) may have inhibitory effects.
This is why the recommended session duration and distance are specific to each device: together they determine the J/cm² dose.
The therapeutic wavelength windows
Not all wavelengths in the red and infrared spectrum are therapeutically active. Science has identified specific windows:
630-670 nm (visible red) Optimal absorption by CCO in the red channel. Strong skin penetration. Primarily effective for skin cells, superficial wounds and collagen stimulation. Demonstrable in skin aging, acne and superficial inflammation.
810-850 nm (near infrared) Deeper penetration, up to 5-10 mm depending on tissue type. Strong anti-inflammatory and analgesic effect. Most commonly researched for musculoskeletal pain, brain injuries and neurological disorders.
1060-1072 nm (deep infrared) Deepest penetration in the near-infrared spectrum. Less studied than the 810-850 nm windows but in more recent studies shows clinical activity in deep tissue inflammation. This is the USP of the Mvolo Platinum Series.
What science confirms and what not
Strong evidence (several RCTs and meta-analyses):
- Wound healing and tissue repair
- Reduced DOMS (muscle soreness after exercise)
- Neck pain and lower back pain
- Arthritis and joint pain
- Skin quality and collagen stimulation
Emerging evidence (positive results, replication ongoing):
- Neurodegenerative disorders (transcranial PBM in dementia)
- Hair loss (low-level laser therapy)
- Depression and SAD (combination with daylight therapy)
Insufficient evidence (studies but inconsistent results):
- Cancer treatment (PBM is being investigated for side effects of chemotherapy, not as a cancer treatment)
- Cognitive performance improvement in healthy people
The science is fair: photobiomodulation is not a panacea. The effects depend on dosage, wavelength and the specific biological condition of the treated tissue. But in the well-researched applications, the evidence is substantial and replicable.
Photobiomodulation vs. other light treatments
Confusion often exists about the difference between:
| Treatment | Mechanism | Scope of application |
|---|---|---|
| Photobiomodulation (PBM) | Mitochondrial activation via photon absorption | Recovery, pain, skin |
| Fototerapi (UV) | DNA damage in skin cells | Psoriasis, vitiligo (clinical) |
| Foodynamic therapy | Photosensitizer + light → free radicals | Destroy cancer cells |
| Infrared sauna | Thermal effect (heat) | Relaxation, blood circulation |
PPE is distinguished by being non-thermal and non-destructive when dosed correctly. It activates cells, it does not damage them.
Frequently asked questions about photobiomodulation and the science
Is photobiomodulation accepted by mainstream medical science? Yes. Photobiomodulation is being researched and applied in regular medical settings. The World Association for Laser Therapy (WALT) publishes clinical dose guidelines. Several hospitals in Europe and North America use PPE for wound healing and rehabilitation. It is not alternative medicine but a complementary treatment method with scientific substantiation.
What is the difference between cold laser and LED therapy? Early PBM research used coherent laser radiation. Later studies showed that non-coherent LED light produces similar biological effects at the same dosage and wavelength. LED therapy is therefore a more cost-effective and safer application of the same principle, suitable for home use.
Which wavelength gives the best result? This depends on the objective. For skin: 630-660 nm. For deep pain and muscle tissue: 810-850 nm. For broad therapeutic effect: a combination of multiple wavelengths that maximize both superficial and deep absorption, such as the Mvolo Elite Series (630, 660, 670, 810, 830, 850 nm).
Does photobiomodulation also work if I am healthy without complaints? In healthy tissue the effect is more limited. PBM works most strongly in damaged, inflamed or stressed tissue. Preventive use can support recovery, but the therapeutic benefit is greatest for active complaints.
How do I know if a product delivers true photobiomodulation? Check the specifications: specific wavelengths in nm, power density in mW/cm², and calculated dosage in J/cm². Products without these specifications cannot claim to deliver photobiomodulation. Mvolo products publish all relevant technical specifications.
Sources: Hamblin MR, Harvard Medical School, photobiomodulation research 2006-2024 | Karu TI, Russian Academy of Sciences | NASA Infrared Wound Healing Documentation | World Association for Laser Therapy (WALT) Dose Guidelines 2024
Read also: What is red light therapy and how does it work at home? | Elite vs Platinum Series: which wavelengths for you?
