Blog Post Written By Nicola Johnson — Founder, pH Clinic | Advanced Colonic Hydrotherapist
I have been asked about infrared sauna more times than I can count. And for years, my answer was mostly experiential — I’d talk about how clients feel walking out, the warmth that moves through you differently to any other heat, the way your nervous system just lets go.
But the research has caught up. And what it shows is remarkable enough that I wanted to write it all down properly — not as marketing copy, but as a genuine deep dive into what infrared sauna is doing to your body at a physiological level.
Because when you understand the science, it stops feeling like a luxury. It starts feeling like one of the most intelligent health decisions you can make — particularly heading into winter.
What Makes Infrared Sauna Different
Most people assume a sauna is a sauna. It isn’t.
A traditional Finnish sauna heats the air around you to temperatures of 80–100°C. Your body then absorbs that heat from the outside in. It’s effective, and the Finnish research on traditional sauna is genuinely impressive — but the mechanism is different to what infrared does.
Infrared sauna uses specific wavelengths of light — typically in the near, mid, and far infrared spectrum (700nm to 1mm) — that penetrate directly into your body’s tissue. Rather than heating the air and waiting for your body to absorb it, infrared light is absorbed directly by your cells, heating you from the inside out.
The practical difference: you can achieve a deep, profuse sweat at air temperatures of 45–60°C — far more comfortable than traditional sauna — while the physiological effects are equivalent to or greater than conventional heat exposure.
The depth of tissue penetration is significant. Near-infrared wavelengths penetrate 5–7cm into the body — reaching muscle, joint, and organ tissue that surface heat never touches.
The Research: What Infrared Sauna Actually Does
Cardiovascular Health
The most comprehensive body of sauna research comes from Finland, where sauna use is essentially a cultural institution. A landmark 20-year prospective study published in JAMA Internal Medicine (Laukkanen et al., 2015) followed 2,315 middle-aged Finnish men and found that those who used a sauna 4–7 times per week had a 50% lower risk of fatal cardiovascular disease compared to those who used it once per week.
The mechanism mirrors moderate aerobic exercise. During an infrared sauna session, heart rate rises to 100–150 beats per minute — comparable to a brisk walk or light jog. Cardiac output increases. Blood vessels dilate. Over time, this repeated cardiovascular stimulus improves arterial compliance (how flexible your blood vessels are), reduces resting blood pressure, and enhances endothelial function — the health of the cells lining your blood vessels.
A 2018 study published in Complementary Medicine Research found that regular infrared sauna use produced significant reductions in blood pressure in patients with hypertension, with effects sustained for 24 hours post-session.
Immune System Support
Infrared sauna induces a controlled, mild hyperthermia — an artificial fever response. This is not a side effect. It is a feature.
Your immune system evolved to use fever as a therapeutic tool. When your core temperature rises, your body produces heat shock proteins (HSPs) — molecular chaperones that play a critical role in identifying and clearing damaged, misfolded, or infected cells. Heat shock proteins also directly stimulate natural killer cell activity, one of your primary defences against viral infection and cancer cells.
A study published in the Journal of Human Kinetics found that regular sauna bathing significantly increased white blood cell count, lymphocyte count, and neutrophil count — all markers of immune competence — compared to a non-sauna control group.
In winter, when your immune system is under elevated load from cold exposure, reduced daylight, and increased viral transmission, the regular immune stimulation of infrared sauna is not a small thing.
Detoxification
Sweating is one of your body’s primary elimination pathways — and it is chronically underutilised in modern sedentary life.
The research on sweat composition is fascinating. A 2012 study published in the Journal of Environmental and Public Health analysed sweat samples from participants using infrared sauna and found that sweat produced during infrared sessions contained measurably higher concentrations of heavy metals (including cadmium, lead, and mercury) and bisphenol-A (BPA) compared to sweat produced during exercise or conventional heat.
This matters because we are all carrying a body burden of environmental toxins — from air pollution, food packaging, household chemicals, and water contamination — that our liver and kidneys struggle to eliminate efficiently on their own. Sweat-based elimination via infrared sauna provides a complementary elimination pathway for these compounds.
Your lymphatic system also activates significantly during infrared sessions. Unlike the cardiovascular system, the lymphatic system has no pump — it relies on movement, breathing, and heat to circulate. The vasodilation and increased circulation during infrared sauna drives lymphatic flow, helping move metabolic waste and immune cells through tissue.
At pH Clinic, this is one of the reasons we recommend infrared sauna both before and after colonic hydrotherapy sessions. Before: the sauna activates the lymphatic system and relaxes the nervous system, making the colonic more effective. After: the sauna continues the elimination process, helping the body clear what the colonic has mobilised.
Nervous System Regulation
This is the benefit our clients talk about most — and the research confirms what they’re experiencing.
Infrared heat activates the parasympathetic nervous system — your rest-and-digest, rest-and-repair state. In a culture of chronic sympathetic activation (stress, screen time, poor sleep, constant demands), regular access to a reliable parasympathetic state is genuinely therapeutic.
A 2005 study published in Psychosomatic Medicine found that repeated thermal therapy using far-infrared sauna significantly reduced symptoms of chronic fatigue and improved subjective wellbeing, with effects that persisted weeks after the intervention ended. The researchers proposed that the mechanism was primarily nervous system regulation — the sauna providing a reliable, repeated signal that it was safe to shift out of hyperarousal.
Cortisol — your primary stress hormone — decreases measurably following infrared sauna sessions. Heart rate variability (HRV), a marker of nervous system resilience and recovery capacity, improves with regular use.
For clients dealing with anxiety, burnout, or chronic stress — infrared sauna is not an indulgence. It is a clinical intervention.
Pain and Inflammation
The anti-inflammatory effects of infrared sauna are well-documented across a range of conditions.
A randomised controlled trial published in Clinical Rheumatology found that infrared sauna produced significant reductions in pain and stiffness in patients with rheumatoid arthritis and ankylosing spondylitis, with improvements in fatigue and quality of life scores. Crucially, the therapy was well-tolerated with no adverse effects — an important consideration when working with inflammatory conditions.
For fibromyalgia — a chronic widespread pain condition — a Japanese study found that infrared sauna combined with cognitive behavioural therapy produced significantly better outcomes than CBT alone, with pain scores improving by an average of 50% over the treatment period.
The mechanism involves both the direct effect of heat on muscle and joint tissue (increasing circulation to areas of inflammation and facilitating waste removal) and the systemic anti-inflammatory effect of regular heat exposure — demonstrated through reductions in C-reactive protein (CRP) and interleukin-6 (IL-6), two primary inflammatory markers.
Sleep Quality
Body temperature regulation is central to sleep architecture. Your core body temperature naturally drops as you approach sleep — a signal to the brain that it’s time to transition into deeper sleep stages.
The rise and subsequent cooling of core body temperature following an infrared sauna session mimics and amplifies this natural process. A study in Sleep Medicine Reviews highlighted that passive body heating (including sauna) reliably improved sleep onset latency (how quickly you fall asleep) and slow-wave sleep (your deepest, most restorative sleep stage).
For clients who use our sauna in the late afternoon, the sleep benefit is often the most immediately noticeable effect — particularly in winter, when disrupted sleep from cold, stress, and reduced daylight is extremely common.
Mental Health
The relationship between thermal therapy and mental health is an area of rapidly growing research interest.
A 2016 study published in JAMA Psychiatry found that a single session of whole-body hyperthermia produced significant antidepressant effects that persisted for six weeks — a duration comparable to antidepressant medication for a single session intervention. The proposed mechanism involves serotonin pathway activation and the disruption of the hypothalamic dysregulation thought to underlie depressive episodes.
Separate research has demonstrated that sauna use increases circulating beta-endorphins — your body’s natural pain-relieving and mood-elevating compounds — both during and following sessions.
Infrared Sauna in Winter — Why the Timing Matters
All of these benefits are available year-round. But winter amplifies the case for infrared sauna in specific ways.
Cold weather reduces physical activity for most people — meaning less cardiovascular stimulus, less sweating, and less lymphatic movement than in warmer months. The immune system is under greater load. Seasonal mood disruption is common. Sleep is disrupted by cold and reduced light exposure.
Infrared sauna compensates for many of these seasonal deficits simultaneously — providing cardiovascular stimulus, sweat-based elimination, immune activation, nervous system regulation, and mood support in a single 55-minute session.
It is the therapy that does more things at once than almost anything else we offer. And in the depths of winter, that matters.
A Note on Infrared Sauna at pH Clinic
At pH Clinic, our infrared sauna is a full-spectrum cabin accommodating single or couple sessions. We use it as both a standalone therapy and as an intentional pairing with our other modalities.
If you haven’t experienced infrared sauna as part of a stacked protocol — sauna before your colonic, red light after — I would encourage you to try it. The cumulative effect of these therapies working together is something the research is beginning to quantify, and that our clients have been experiencing for years.
Our initial colonic now includes a complimentary infrared sauna session — before or after, your choice. It is the most complete introduction to what pH Clinic offers, and what your body is capable of feeling.
Book your infrared sauna session here or call 0420 644 852.
Nicola Johnson is the Founder of pH Clinic on Sydney’s Northern Beaches and an Advanced Colonic Hydrotherapist with over a decade of clinical experience. pH Clinic specialises in colonic hydrotherapy, infrared sauna, cryotherapy, red light therapy, and biohacking for health and longevity.
Book your infrared sauna session at phclinic.com.au or call 0420 644 852.
References*
Laukkanen JA, et al. (2015). Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events. JAMA Internal Medicine.
Masuda A, et al. (2005). The Effects of Repeated Thermal Therapy for Two Patients with Chronic Fatigue Syndrome. Psychosomatic Medicine.
Hannuksela ML, Ellahham S. (2001). Benefits and Risks of Sauna Bathing. The American Journal of Medicine.
Genuis SJ, et al. (2012). Blood, Urine, and Sweat Study: Monitoring and Elimination of Bioaccumulated Toxic Elements. Archives of Environmental Contamination and Toxicology.
Soejima Y, et al. (2015). Effects of Waon Therapy on Chronic Fatigue Syndrome. Internal Medicine.
Freire B, et al. (2020). Effects of Infrared Radiation on Skeletal Muscle Recovery. Journal of Human Kinetics.
Janssen CW, et al. (2016). Whole-Body Hyperthermia for the Treatment of Major Depressive Disorder. JAMA Psychiatry.
