How PBM May Work

How PBM May Work

1. Light Reaches the Tissue

Specific wavelengths of red and near-infrared light are directed toward the body. Some of the light is reflected or scattered, while some enters the skin and underlying tissues. Red light generally interacts more strongly with superficial tissues, while near-infrared wavelengths may reach relatively deeper tissue layers.
Near-infrared light can generally reach deeper tissues than visible red light, although actual penetration varies.

2. Cells Absorb Part of the Light

Light that penetrates tissues may be absorbed by photosensitive molecules inside cells. In PBM research, cytochrome c oxidase within the mitochondrial electron transport chain is widely regarded as one of the primary molecules capable of absorbing photons. Cytochrome c oxidase takes part in oxygen utilization and mitochondrial energy metabolism. For this reason, researchers propose that PBM can modulate mitochondrial function and cellular energy-related processes. Nevertheless, contemporary studies indicate the mechanisms behind PBM are not limited to this single molecule; instead, they involve a wide range of cellular and molecular reactions.
Researchers believe that mitochondria are one important target of PBM, although the complete mechanism is still being studied.


3. Mitochondrial Activity May Be Influenced.

· Cellular communication

· Local blood circulation

· Inflammatory signaling pathways

· Tissue maintenance

· Recovery-related bodily processes

Nevertheless, identical outcomes cannot be guaranteed across all devices, dosage regimens and individual users. Treatment results vary depending on wavelength, light dose, application duration and targeted body areas. A 2025 umbrella review of randomized controlled trials has confirmed that the strength of evidence supporting PBM differs widely across various health conditions. Accordingly, PBM should never be marketed as a universal remedy capable of resolving all health concerns. 

Mitochondria are often referred to as the "powerhouses" of cells. They generate ATP using oxygen and nutrients. PBM may alter cellular energy status and associated signaling by modulating mitochondrial respiratory activity.
PBM does not simply “add energy” to the body. It may influence how cells produce and manage energy.


4. Cells May Adjust Their Response

After cells receive the light signal, temporary biological responses may be triggered within the body. These responses can further modulate the following biological processes:

Why PBM Is Not Simply Heat Therapy

Many people assume that red light therapy works because it feels warm. While some devices may generate mild warmth during use, warmth is not the primary mechanism behind photobiomodulation (PBM).

Heat Therapy

Heat therapy works by raising the temperature of the skin or underlying tissues, which may help promote relaxation and temporary increases in local blood flow.

Common examples include:

  • Heating pads
  • Hot towels
  • Infrared saunas
  • Warm baths

The therapeutic effect comes primarily from heat.

Photobiomodulation (PBM)

PBM works differently.

Instead of relying on temperature, PBM uses specific wavelengths of red and near-infrared light that may interact with light-sensitive molecules inside cells. Researchers believe this interaction can influence normal cellular processes under appropriate treatment conditions.

Some PBM devices may feel warm during use because of factors such as:

  • Heat generated by LEDs or other electronic components
  • Close contact with the skin
  • Higher power output
  • Longer treatment sessions
  • Built-in heating functions (on some devices)

However, any warmth is generally a secondary effect rather than the primary mechanism of PBM.
PBM is primarily a light-based process rather than a heat-based process, although some devices may produce mild warmth during use.

How Is PBM Different from High-Powered Lasers?

What Is a Laser?

A laser is simply a type of light source.

Depending on how it is designed, a laser can be used for surgery, cosmetic procedures, industrial applications—or photobiomodulation (PBM).

A laser is a technology, not a treatment.

PBM Can Use LEDs or Low-Level Lasers

Photobiomodulation does not describe the device—it describes how light interacts with the body.

PBM can be delivered using:

  • LEDs
  • Low-level lasers
  • Other controlled red or near-infrared light sources

This is why the term PBM has largely replaced Low-Level Laser Therapy (LLLT) in modern research.

How Is It Different?

The biggest difference is the purpose, not simply the type of light.
PBM High-Powered Laser
Supports normal cellular activity Cuts or reshapes tissue
Uses controlled light doses Uses concentrated, high-energy light
Does not aim to damage tissue Controlled tissue damage may be part of treatment

Does PBM Burn the Skin?

Generally, no.

Some devices may feel warm during use, but PBM is designed to work through light rather than intentionally heating or destroying tissue.

Key Takeaway

Laser describes a type of light source. PBM describes how controlled light is used to support biological activity.

Not every laser treatment is PBM, and not every PBM device uses a laser.