Recovery from infection does not always end when the infection itself has cleared.

Some people continue to experience fatigue, cognitive difficulties, pain, neurological symptoms, sleep disturbance and reduced exercise tolerance long after the acute illness has resolved.

Different infections can lead to different long-term consequences, but several shared biological mechanisms are being investigated.

These include persistent immune activation, inflammatory signalling, autonomic dysfunction, mitochondrial stress and altered cellular metabolism.

In some people, the body appears to remain in a prolonged state of physiological stress rather than returning fully to its pre-illness baseline.

HBOT may be relevant because of its ability to influence oxygen availability, inflammatory pathways, vascular function and tissue recovery.

Photobiomodulation is of particular interest where mitochondrial dysfunction and impaired cellular energy production are involved.

The important point is that two people can have different original infections but develop a surprisingly similar cluster of long-term symptoms.

That is why understanding the biology behind the symptoms can sometimes be more useful than looking solely at the original infectious diagnosis.

Crohn’s disease is a chronic inflammatory bowel condition in which the immune system drives persistent inflammation within the digestive tract. It can cause abdominal pain, diarrhoea, fatigue, weight loss, reduced nutrient absorption and periods of significant flare-up followed by remission.

The biology is not confined to the bowel alone. Ongoing inflammation can affect energy levels, immune regulation, tissue repair and overall recovery, while severe or prolonged disease can place considerable metabolic stress on the body.

This is why therapies that influence inflammation, oxygen delivery, circulation, mitochondrial function and tissue repair are of particular scientific interest.

HBOT has been studied in inflammatory bowel disease, including Crohn’s disease, with research examining its effects on inflammatory signalling, tissue oxygenation and healing within the gastrointestinal tract. Photobiomodulation is also being investigated for its ability to influence inflammatory pathways, mitochondrial activity and cellular repair.

At Breathe, Crohn’s disease has particular significance because it forms part of the personal history behind the organisation itself. The experience of living with chronic inflammatory illness helped shape the emphasis we place on understanding the science, supporting recovery and looking beyond symptom management alone.

Lyme disease is caused by infection with Borrelia bacteria, usually transmitted through the bite of an infected tick.

When identified early it is normally treated with antibiotics. However, some people continue to experience fatigue, pain, cognitive difficulties, neurological symptoms and reduced exercise tolerance after standard treatment.

The reasons for persistent symptoms remain an area of continuing research.

Potential mechanisms include ongoing inflammatory signalling, immune dysregulation, neurological injury and changes in cellular metabolism.

The role of HBOT has been investigated because hyperbaric oxygen can increase tissue oxygen availability and influence inflammatory and immune pathways.

Photobiomodulation is relevant for a different reason: its effects on mitochondrial function, inflammation, circulation and neural tissue.

The objective is not to suggest that either therapy replaces appropriate antimicrobial treatment.

The interest lies in supporting the biological systems that may remain disrupted during prolonged recovery.

Long COVID is a complex post-viral condition in which symptoms continue for months or sometimes years after the initial infection.

People may experience profound fatigue, brain fog, breathlessness, headaches, dizziness, altered heart rate, sleep disturbance, exercise intolerance and worsening of symptoms after exertion.

There is unlikely to be one single mechanism responsible for every case. Research has identified several overlapping areas of interest, including persistent immune activation, endothelial dysfunction, microvascular changes, altered oxygen utilisation, autonomic nervous-system dysfunction and mitochondrial impairment.

One important area of research concerns the ability of tissues to receive and use oxygen efficiently. A person can have a normal oxygen saturation reading while still experiencing problems at the level of the microcirculation, tissue oxygenation or cellular energy production.

HBOT has therefore been studied for its potential effects on tissue oxygenation, brain function, circulation, inflammation and neurological recovery.

Photobiomodulation is also being investigated because red and near-infrared light can interact with mitochondria and influence ATP production, nitric-oxide signalling, inflammation and cellular metabolism.

The interest in these therapies is therefore not simply about “giving more oxygen” or “using red light”. It is about influencing several of the biological systems that appear to become disrupted in post-viral illness.

Myalgic Encephalomyelitis / Chronic Fatigue Syndrome is far more than ordinary tiredness.

It is a complex multisystem illness characterised by profound fatigue, cognitive difficulties, sleep disturbance, autonomic symptoms and, importantly, post-exertional malaise — a worsening of symptoms following physical or mental activity that would previously have been tolerated.

Research continues to investigate abnormalities involving the immune system, autonomic nervous system, cellular metabolism and mitochondrial energy production.

One important question is whether cells are able to generate and manage energy normally during and after exertion. Altered oxygen utilisation, metabolic dysfunction and impaired recovery have therefore become important areas of scientific investigation.

HBOT is relevant because it changes the oxygen environment available to tissues and may influence circulation, inflammation and cellular metabolism.

Photobiomodulation acts more directly at the cellular level, particularly through its interaction with mitochondria and the pathways involved in ATP production.

Neither therapy should be viewed simply as a “fatigue treatment”. The scientific interest lies in whether they can influence the underlying systems responsible for energy production, oxygen utilisation, inflammatory regulation and recovery.

Autoimmune conditions occur when the immune system begins attacking the body's own tissues.

The exact target differs between diseases, but persistent inflammation is a common feature.

Inflammatory signalling can alter circulation, mitochondrial activity, energy production and tissue repair, which helps explain why fatigue and reduced resilience occur across many different autoimmune diseases.

HBOT can influence several inflammatory and immune pathways while increasing oxygen availability to tissues.

Photobiomodulation can also modulate inflammatory signalling and mitochondrial function.

This does not mean every autoimmune condition responds identically.

The relevance of these therapies depends upon the disease, the symptoms, the stage of illness and the biological processes involved.

But it explains why inflammation and cellular energy are recurring themes across apparently unrelated chronic conditions

Fibromyalgia is a chronic condition characterised by widespread pain, fatigue, sleep disturbance, cognitive symptoms and heightened sensitivity to touch, pressure and other sensory input.

For many years it was poorly understood because conventional scans and tests often failed to show an obvious structural cause for the severity of the symptoms.

Modern research increasingly recognises that fibromyalgia involves changes in the way the nervous system processes pain.

This phenomenon is known as central sensitisation. The brain and spinal cord can become increasingly responsive to signals that would normally produce little or no pain, effectively turning up the “volume” of the pain-processing system.

Other research has identified abnormalities involving autonomic regulation, microcirculation, mitochondrial function and inflammatory signalling.

HBOT has been studied in fibromyalgia because of its potential effects on brain metabolism, neuroplasticity, tissue oxygenation and pain-processing networks.

Photobiomodulation has also been extensively studied in musculoskeletal pain because of its effects on mitochondria, inflammation, nitric oxide and local tissue recovery.

This makes fibromyalgia a good example of why chronic pain cannot always be understood by looking only at muscles and joints. The nervous system, cellular metabolism and inflammatory pathways all matter.

Cancer is not one single disease. It is a broad group of conditions characterised by abnormal cells growing and dividing in an uncontrolled way, with very different biological behaviour depending on the cancer type, stage and tissue involved.

For Breathe, the important distinction is that HBOT and photobiomodulation are not alternatives to oncology treatment. Their relevance is mainly around the biological consequences of cancer and its treatment: tissue injury, inflammation, fatigue, neuropathy, impaired healing, radiation damage, lymphatic problems and reduced quality of life.

Hyperbaric oxygen has a recognised role in selected forms of late radiation tissue injury, where radiotherapy has damaged blood vessels and reduced oxygen delivery to surrounding healthy tissue. By increasing tissue oxygenation and supporting new blood-vessel formation and repair, HBOT can help improve the environment in which damaged tissue has to heal.

Photobiomodulation has also become increasingly important in supportive cancer care. It has been studied for complications including oral mucositis, pain, lymphoedema, radiation-related skin injury and peripheral neuropathy. A recent systematic review and meta-analysis of head-and-neck cancer trials found that PBM significantly reduced severe oral mucositis and severe oral pain.

Cancer naturally raises an additional question: could stimulating cellular activity also stimulate tumour cells? This has been studied extensively. Systematic reviews of clinical and preclinical evidence have found PBM used within established clinical parameters to be oncologically safe in supportive-care applications, without evidence that it increases recurrence or tumour growth in the clinical studies reviewed.

The key is therefore appropriate use alongside oncology care. The objective is not to treat the cancer itself, but to support healthy tissue, recovery and treatment-related complications where the evidence supports doing so.

Chronic pain is fundamentally different from short-term pain following an injury.

Acute pain is normally protective. It tells the brain that something has been damaged and encourages us to protect the affected area while it heals.

With chronic pain, however, the pain-processing system itself can change.

Nerves may become more sensitive, inflammatory signals may persist and the spinal cord and brain can begin amplifying incoming signals. This process is known as central sensitisation.

At the same time, local tissue problems may continue to contribute through inflammation, poor circulation, nerve irritation or incomplete healing.

HBOT is being investigated in chronic pain because it can influence oxygen delivery, inflammation, damaged tissue and neurological function.

Photobiomodulation has a substantial research base in pain and musculoskeletal conditions because it can affect local inflammation, mitochondrial activity, nitric oxide and nerve signalling.

This is why chronic pain often requires a broader approach than simply trying to block the pain signal itself

Neuropathy occurs when nerves are damaged or stop functioning normally.

Symptoms may include burning, tingling, numbness, electric-shock sensations, hypersensitivity or weakness.

There are many possible causes, including diabetes, chemotherapy, injury, infection and autoimmune disease.

Nerve cells are metabolically demanding. They require a reliable supply of oxygen and energy to maintain electrical activity, repair membranes and transport materials along the length of the nerve.

When circulation, mitochondrial function or tissue oxygenation are impaired, nerve recovery can become more difficult.

HBOT is of interest because it can increase oxygen availability and support vascular and tissue repair processes.

Photobiomodulation has also been widely investigated in peripheral nerve injury because red and near-infrared light can influence mitochondrial activity, inflammatory signalling and cellular repair.

The aim is not simply to suppress the sensation of pain or tingling, but to support the biological environment in which damaged nerves have to function and recover

Most people recover from concussion relatively quickly, but a proportion continue to experience symptoms for months or longer.

These can include headaches, dizziness, poor concentration, memory problems, fatigue, sleep disturbance, visual sensitivity and changes in mood.

Following brain injury, some tissue may be destroyed immediately, while other areas can remain structurally present but metabolically impaired.

Researchers have described changes involving cerebral blood flow, inflammation, oxygen metabolism, mitochondrial function and neural connectivity.

HBOT has received significant research attention in this area because increasing oxygen availability may influence brain metabolism and neuroplasticity.

The concept of neuroplasticity is particularly important. The brain is capable of reorganising and creating new functional connections, particularly when damaged areas are supported by an improved biological environment.

Photobiomodulation is also being studied in brain injury because near-infrared wavelengths can influence mitochondrial function, cerebral blood flow and neurological signalling.

Together, these areas of research have moved the discussion beyond the older assumption that neurological recovery necessarily stops after the initial healing period

Multiple sclerosis is an autoimmune disease in which the immune system attacks myelin, the protective covering surrounding nerve fibres within the brain and spinal cord.

Damage to myelin interferes with the transmission of electrical signals through the nervous system.

Symptoms can therefore vary enormously and may include fatigue, weakness, pain, altered sensation, problems with balance, visual disturbance and cognitive changes.

Beyond demyelination itself, researchers also study inflammation, mitochondrial dysfunction, oxidative stress and progressive damage to nerve cells.

HBOT has a long history of investigation in multiple sclerosis, particularly around oxygen delivery, neurological function and fatigue.

Photobiomodulation has attracted more recent interest because of its effects on mitochondria, inflammatory signalling and nervous-system tissue.

These therapies are not substitutes for disease-modifying treatment, but they illustrate a broader principle: supporting energy metabolism, circulation and cellular function may remain relevant even where the primary disease process is autoimmune

Parkinson’s disease is characterised by progressive loss of specific nerve cells involved in producing dopamine, particularly within an area of the brain called the substantia nigra.

The visible symptoms — tremor, rigidity and movement difficulties — are only part of the condition. People may also experience fatigue, sleep disturbance, pain, autonomic symptoms and cognitive change.

At the cellular level, mitochondrial dysfunction, oxidative stress, inflammation and impaired energy metabolism are major areas of research.

This has made photobiomodulation particularly interesting in neurodegenerative research.

Near-infrared light is being studied for its ability to influence mitochondrial activity, cellular energy production, blood flow and neuroprotective signalling.

HBOT is also being investigated in neurological and neurodegenerative conditions because of its effects on oxygen availability, circulation and cellular signalling.

This remains an evolving area of research, but it is one of the clearest examples of why mitochondria have become such an important target in modern neuroscience

Osteoarthritis is often described simply as “wear and tear”, but the biology is more complicated.

It involves changes in cartilage, underlying bone, the joint lining and surrounding tissues, together with inflammatory signalling that can contribute to pain and stiffness.

Cartilage has a very limited blood supply, which makes repair difficult.

As joint degeneration progresses, muscles around the joint may weaken, movement can reduce and inflammation can become persistent.

Photobiomodulation has been widely researched in osteoarthritis and musculoskeletal conditions because it can influence pain, inflammatory signalling, mitochondrial activity and local circulation.

HBOT has also been investigated for its effects on oxygen delivery, tissue metabolism and inflammatory pathways.

The objective is not to claim that damaged cartilage can simply be restored by either therapy, but to support the wider biological environment affecting pain, inflammation, mobility and recovery.

Tendons connect muscles to bones and are designed to tolerate repeated mechanical loading.

However, their blood supply is relatively limited compared with many other tissues, which can make recovery from injury slow.

Chronic tendinopathy is no longer thought of simply as persistent inflammation. It can involve changes in collagen structure, cell function and the way the tendon responds to mechanical stress.

Photobiomodulation has been extensively investigated in tendon and soft-tissue recovery because of its effects on mitochondrial activity, collagen-related processes, inflammation and cellular repair.

HBOT may also support tissue recovery by increasing oxygen availability and influencing vascular and repair processes.

These therapies are most relevant when combined with appropriate rehabilitation and loading rather than being viewed as replacements for movement and strengthening

Wound healing is an energy-intensive biological process.

Cells need oxygen to produce collagen, fight infection, build new blood vessels and reconstruct damaged tissue.

When circulation is poor, oxygen cannot reach the wound efficiently and healing may slow dramatically.

This is particularly relevant in diabetes and peripheral vascular disease.

Hyperbaric oxygen has an established role in selected difficult-to-heal wounds because it can dramatically increase the amount of oxygen dissolved in the blood and improve delivery to compromised tissues.

Repeated exposure can also influence angiogenesis — the formation of new blood vessels — as well as immune activity and collagen production.

Photobiomodulation has also been widely researched in wound healing because red and near-infrared light can influence cellular energy production, inflammation and tissue repair.

This is one of the clearest demonstrations of how oxygen availability and cellular energy can directly influence the body's ability to heal.

Diabetes affects much more than blood sugar.

Over time, elevated glucose can damage blood vessels and nerves, particularly in the feet and lower limbs.

This can produce a combination of poor circulation, neuropathy, reduced immune function and impaired wound healing.

The result is that relatively minor injuries can sometimes become persistent ulcers.

HBOT is already used within conventional medicine for selected diabetic foot ulcers because improving oxygen delivery can support wound healing and infection control.

Photobiomodulation has also been investigated in diabetes-related neuropathy, circulation and wound repair.

The mechanisms are complementary: HBOT primarily changes the oxygen environment available to tissues, while photobiomodulation influences cellular energy production and signalling

Not everyone experiencing chronic symptoms fits neatly into a single diagnostic category.

Some people experience persistent fatigue, poor concentration, slow recovery, reduced exercise tolerance or a general loss of resilience despite extensive investigation.

These symptoms can arise from many different causes.

But several recurring biological systems are often involved:

mitochondrial energy production, oxygen delivery, circulation, inflammation, autonomic regulation, sleep and neurological function.

This is why Breathe places so much emphasis on understanding the underlying physiology rather than simply matching one therapy to one diagnosis.

HBOT and photobiomodulation affect different parts of that physiology.

HBOT changes the pressure and oxygen environment surrounding the body's tissues.

Photobiomodulation influences cellular and mitochondrial activity through light.

Used appropriately, they provide two different ways of influencing some of the systems that are fundamental to recovery