Humans have associated light with health for thousands of years, but modern phototherapy began to develop scientifically in the late nineteenth and early twentieth centuries.

One of the pioneers was the Danish physician Niels Finsen, whose work using concentrated light to treat disease earned him the Nobel Prize in Physiology for Medicine in 1903.

The modern story of photobiomodulation began more directly in 1967 with Hungarian physician Endre Mester. Mester was experimenting with a newly developed low-powered ruby laser. He was originally investigating whether laser light might affect tumour growth.

It did not produce the effect he expected. Instead, he noticed something completely unexpected. The hair on treated mice grew back faster.

He later observed improved wound healing and went on to use low-level laser light in patients with difficult-to-heal ulcers.

It was one of those important scientific discoveries that happened partly by accident.

Red-Light Photobiomodulation, often shortened to PBM, is the use of specific wavelengths of red and near-infrared light to influence biological activity within the body.

Unlike ultraviolet light, these wavelengths are non-ionising and do not work by damaging tissue. They also do not rely on heat as their main mechanism.

Instead, particular wavelengths of light are absorbed by molecules inside cells and trigger a series of biological responses.

At Breathe, Red Light Therapy is therefore not simply about shining a bright red light onto the body.

It is about delivering light at carefully selected wavelengths and intensities so that the body's cells can respond to it.

HBOT and Red Light Therapy work through different biological pathways, which makes them particularly complementary when used together.

HBOT increases oxygen availability throughout the body and creates a temporary oxygen-rich environment within the tissues. Red Light Therapy then acts directly on cells, particularly the mitochondria, using specific wavelengths of red and near-infrared light to influence energy production, circulation, inflammatory signalling and cellular repair.

In simple terms:

HBOT helps deliver more oxygen to the tissues.

Red Light Therapy helps stimulate the cells that use that oxygen.

Following an HBOT session with Red Light Therapy therefore provides two different but complementary physiological stimuli within the same visit.

This combination is especially relevant where the objective is recovery, tissue health, cellular energy, inflammation management or physical performance.

It is not simply about adding two therapies together — it is about using two different mechanisms that support the same underlying processes of cellular function, recovery and adaptation.

Light is made up of particles of energy called photons.

When red and near-infrared photons reach the body, some are reflected, some are scattered, and some penetrate into the tissues.

The wavelengths commonly used in photobiomodulation are particularly interesting because they can pass through the skin and interact with structures within cells.

One of the most extensively studied targets is found inside the mitochondria.

Mitochondria are the tiny structures inside our cells responsible for producing much of the energy the body needs to function.

A key mitochondrial enzyme called cytochrome c oxidase can absorb red and near-infrared light. That interaction can influence mitochondrial activity, oxygen utilisation and the production of ATP — the molecule cells use as their immediate source of energy.

Put simply

Your cells can respond to light.

Certain wavelengths of red and near-infrared light penetrate tissue and interact with the machinery responsible for cellular energy production.

The result is not simply “more energy”.

The light acts as a biological signal, influencing how cells behave.

Mitochondria are often described as the power stations of the cell, but their role goes far beyond simply producing energy.

They take oxygen and nutrients and convert them into ATP — adenosine triphosphate, the immediate source of energy used by cells throughout the body.

ATP is required for almost everything a cell needs to do, including:

• repair and regeneration
• muscle contraction and movement
• cell-to-cell signalling
• protein production
• immune activity
• maintaining cell membranes and normal cellular function

This matters because cells under greater physical, metabolic or inflammatory stress often have a higher demand for energy.

Photobiomodulation interacts with mitochondrial processes, particularly through light-sensitive components of the respiratory chain involved in ATP production. When red and near-infrared light is absorbed, it can influence mitochondrial activity and trigger wider cellular signalling responses.

Those effects do not remain confined to energy production alone. Changes in mitochondrial activity can influence inflammation, circulation, oxidative signalling, repair mechanisms and the way cells respond to stress.

That helps explain why photobiomodulation has been studied across such a wide range of tissues and applications, including muscle, skin, nerves, joints, wounds and the brain.

In simple terms, photobiomodulation works at one of the most fundamental levels of biology: the machinery that helps cells produce energy, communicate and repair themselves.

The mitochondrial effect is only part of the story. Photobiomodulation can also influence cellular signalling pathways involving:

Nitric oxide, which plays an important role in blood-vessel function and circulation.

Reactive oxygen species, which in controlled amounts act as important signalling molecules.

Calcium signalling, which helps regulate cellular activity.

Inflammatory pathways, influencing how cells respond to injury and physiological stress.

Growth factors, which are involved in repair and tissue remodelling.

In everyday language

• The light gives cells a stimulus.
• The cells detect that stimulus and alter their behaviour.
• That can influence how efficiently they produce energy, communicate, respond to inflammation and carry out repair.

Although they are often grouped together under the term Red Light Therapy, red and near-infrared wavelengths do not behave identically.

Red light is visible and generally acts more superficially.

Near-infrared light is largely invisible to the human eye and penetrates more deeply into tissue.

This means the two wavelength ranges can complement one another.

Red light is particularly relevant to the skin and more superficial tissues, while near-infrared wavelengths can reach deeper structures.

This is why many modern photobiomodulation systems use a combination of the two.

Photobiomodulation is not an experimental curiosity.

It has been studied for decades across laboratory research, clinical trials, randomised controlled trials and systematic reviews.

Research has covered PBM in areas  that includes:

• pain
• inflammation
• wound healing
• musculoskeletal conditions
• nerve injury
• skin health
• hair growth
• exercise recovery
• oral mucositis
• neurological conditions
• and tissue repair

A 2025 international evidence-based consensus review concluded that photobiomodulation is a safe treatment and identified effective clinical applications including peripheral neuropathy, androgenetic alopecia, several forms of wound ulcer, diabetic-foot-ulcer pain and acute radiation dermatitis.

Other reviews have documented clinical research across musculoskeletal disorders, wounds, scars and neurological applications.

The exact results naturally depend on the condition being treated, the wavelength used, the power delivered and the overall dose.

But the central biological effect of red and near-infrared light is now well established.

One of the most important ideas in photobiomodulation is that more light is not automatically better.

PBM demonstrates what scientists call a biphasic dose response.

That means too little light may produce very little effect, an appropriate dose can produce the desired biological response, and excessive exposure may reduce that response.

So effective photobiomodulation depends on more than simply buying the most powerful red light available.

The important variables include:

• wavelength,
• power density,
• energy delivered,
• distance from the light,
• exposure time,
• treatment area,
• and frequency of sessions.

The combination of these variables determines the actual biological dose.

Put simply

• Think of light more like exercise than medication.
• Too little stimulus may do very little.
• The right stimulus can encourage adaptation.
• But simply increasing the dose indefinitely does not necessarily improve the result.

A Red Light Therapy session is remarkably simple from the client's perspective.

You lay down on the bed and close the lid - like a sun bed and the body is exposed to red and near-infrared wavelengths for a defined period.

The light itself is doing the work.

While you relax, photons are penetrating into the tissues and being absorbed by light-sensitive molecules within cells.

That interaction can influence mitochondrial activity and initiate downstream biological signalling.

A session may only take a relatively short time, but the cellular responses triggered by the light can continue beyond the exposure itself.

Like HBOT, photobiomodulation is used as a course of exposures rather than as a one-off event.

The reason is straightforward.

• Each session provides a temporary biological stimulus.
• Repeated exposure allows that stimulus to be applied consistently over time.
• This gives the body repeated opportunities to respond, adapt and repair.

For many applications, the cumulative effect of a programme is therefore more important than the experience of a single session.

Not every red-looking light produces the same biological effect.

Specific wavelengths are selected because biological tissues absorb and respond to them differently.

Photobiomodulation research most commonly uses wavelengths within approximately:

600–700 nm for red light

and

760–900 nm for near-infrared light.

These wavelength ranges correspond closely with areas where important cellular molecules, including mitochondrial cytochrome c oxidase, absorb light.

This is why professional PBM equipment specifies wavelength rather than simply describing itself as a red lamp.

The colour is only the visible part of the story.

People sometimes assume that Red Light Therapy works because the lamps make the body warm. That is not the principal mechanism.

• Heat therapies work by increasing tissue temperature.
• Photobiomodulation works through photochemical and photophysical interactions between light and biological tissue.

In correctly delivered PBM, the objective is not to heat or damage tissue,  it's to trigger cellular responses using light.

That distinction is fundamental.

If HBOT is about changing how oxygen behaves around the body's cells, photobiomodulation is about changing how the cells respond to light.

• At the correct wavelengths and dose, cells can detect that light and respond to it.
• The mitochondria respond.
• Cellular signalling changes.
• Circulation change.
• Inflammatory pathways change.
• Repair mechanisms change.

That is photobiomodulation.

Light is not simply something we see. At the cellular level, it is something the body can use.