top of page
  • Writer's pictureKate Duder

How does Infrared Sauna and RLT actually work?

Updated: May 15

Sauna has been used for hundreds of years as a health treatment across the world and red-light therapy (RLT) is used by NASA for growing plants in space! Both treatments have been recognised in several research studies for their benefits to health, exercise performance and longevity.

So let's look at Infrared Sauna

Infrared Sauna

The appeal of sauna for those with chronic illness or injury is that the heat causes reactions in the body that are similar to moderate exercise, increasing circulation and enabling detoxification along with the benefits these provide. It's also a more tolerable heat than traditional sauna, eliciting a deep sweat at a lower temperature with the added benefits of infrared technology. For athletes or those with a regular fitness regime, sauna can enhance the benefits of exercise providing further adaptation and supports overall health, wellbeing, and longevity.

Infrared Sauna has infrared heat panels on all sides of the sauna. The wavelengths from these panels penetrate and heat your body tissues directly (rather than heating the air around you in a traditional hot rock sauna) causing an intense sweat at a lower heat tolerance.

The infrared wavelength of light (invisible to the human eye and felt as heat) penetrates body tissues because the frequency of the wavelength resonates at the same frequency as the water and other molecules stored in the skin and body tissues. It then penetrates up to 1 ½ inches further into denser tissues such as muscle mass and organs increasing the core temperature of the body and tissues. This creates the platform for a range of physiological changes due to vasodilation and increased blood flow. When you increase blood flow to tissues and organs this also delivers additional oxygen and nutrients to organs and tissues leading to improved circulation, healing, relaxation, mobilisation and release of toxins, improved immunity (see below) and more.

To understand the amazing effects of sauna its good to understand hormesis. Hormesis is a term for types of good stress on our body that stimulate our systems to make cellular adaptations that make us stronger, healthier and more resilient. Just as exercise provides a certain stress to the body that allows us to adapt and get stronger and fitter, regular infrared sauna provides hyperthermic conditioning, that also causes positive changes within the body.

Being exposed to heat, also activates a special type of protein in our body called Heat Shock Proteins (HSP). HSP’s play many roles that are enhanced with infrared sauna, including:

  • regulating the immune system and suppressing autoimmune overactivity.

  • the repair and clean out of damaged cells.

  • the removal of free radicals and growing antioxidant capacity, which results in less muscle breakdown from less oxidative stress.

  • improved energy through mitochondria health (the energy producers of our cells) - heat exposure has been shown to stimulate the body to make more mitochondria (and therefore an improved capacity to make energy), grow stronger bigger mitochondria and clean out and repair damaged mitochondria.

  • increase growth hormone levels which lead to greater exercise performance.


Longevity and Brain Health

A 20 year study of 2,315 men in Finland found that those using sauna 2-3 times per week (as opposed to once a week) had lowered risk of dementia and Alzheimers and were 24% less likely to die to from all causes. Plus the effects were greater with increased sauna use. Those who used the sauna 4-7 times per week were a massive 40% less likely to die from all causes! (1)

tension headaches

Tension Headaches

Infrared sauna has been shown to reduce chronic tension headaches by up to 44% in intensity after 6 weeks of treatment. (2)

chronic pain and fibromyalgia

Chronic Pain and Fibromyalgia

Several studies have shown that sauna heat exposure cause a significant increase in beta-endorphin levels, which are the bodies natural pain killers. (3,4,5)

Patients with chronic pain disorders detected an increased likelihood of return to work after 2 years following regular sauna, along with decreases in anger scoring indicating improved mood. (6)

Fibromyalgia patients undergoing sauna treatment via the Waon Therapy, experienced a significant reduction in pain by between 11 and 70% after the first session, which became stable after 10 treatments. (7)

The combination of sauna and underwater therapy improved the pain and symptoms of Fibromyalgia patients by 31-77% after 12 weeks and remained relatively stable (28-68%) during the 6-month follow-up period. (8)

chronic illness ME/CFS

Reduce symptoms of Myalgic Encephalomyelitis/ Chronic Fatigue Syndrome

In several studies of ME/CFS, participants reported decreased fatigue, improved anxiety and depression scores, reduced pain and less sleep disturbance. In one study (Amano et al. 2015) 77.8% of participants noted improved symptoms after 8 weeks of regular sauna. (9,10)

Joint pain

Joint Pain and Arthritis

More than 50% of patients reported relieved rheumatic pain and improved joint mobility with sauna use. Some of the patients temporarily experienced worse pain the following day before seeing the improvements in symptoms, however many also reported that this could be prevented by a cool shower after the sauna. (11,12)


Boost Mood and Reduce Stress and Anxiety

Because sauna heat causes a mild stress on the body, your brain produces and releases more endorphins (happiness hormones) in response and can lower cortisol levels, (your body’s main stress hormone). (13)

In addition it has been shown to increase the parasympathetic system and improve HRV (Heart Rate Variability), which increases relaxation and has an impact on recovery, healing and feelings of stress and anxiety. (14)

Patients diagnosed with mild depression reported improved in physical symptoms such as pain/tension/stress, improved appetite and improved relaxation. (15)

heart health

Cardiovascular Health and HRV

Heat therapy like sauna can stimulate the autonomic nervous system and improve HRV and cardiac function.

149 patients with Chronic Heart Failure demonstrated small but improved 6 minute walking distances and reduced cardiothoracic ratios on chest x-rays (reflecting reduced heart size) and improved classifications of disease (according to the New York Heart Association) after 2 weeks of sauna therapy. (16)



Your skin acts as an important route of excretion of toxins, however many people don't sweat much. Regular sauna enhances detoxification pathways for the elimination of heavy metals and chemicals from our environment including prescription medications. Ensuring detoxification helps recover from and prevent chronic illness. (17)

Police officers with employment-related drug and toxic exposure symptoms improved their quality of health post sauna treatment reporting fewer “poor physical health” days (1.8 vs 9.3 days); fewer “sick days” (0.3 vs 2 days); more sleep hours (7.6 vs 5.8 hours) along with lessened neurotoxicity scoring. (18)

athletic performance

Athletic Performance

Studies of athletes with daily post exercise sauna showed an increase in the oxygen content of the blood by 53.3%, increased Haemoglobin concentration in blood by 5.2% (increase oxygen carrying capacity) and a right shift of the oxygen-hemoglobin dissociation curve (favours the release of O2 to tissues). (19)

A study of male distance runners using the sauna for 30 minutes post-workout for just three weeks increased their blood volume and therefore run time to exhaustion by a huge 32%! (20,21,22)

The Science behind Red Light Therapy

red light therapy

To understand how RLT works, its important to understand a bit of cell biology. Within every cell are mitochondria (‘power stations’ of the cells) that are responsible for producing almost all the energy the body needs. Every cell needs energy for stem cell production, inflammation, growth and repair mechanisms, cell survival, cell turnover and more. The dysfunction of mitochondria are sited in many conditions and diseases.

RLT units produce red and near infrared wavelengths of light that cause a photochemical reaction (a reaction driven by photons/light) within our cells. Inside the cells are the mitochondria and inside the mitochondria are chromophores (which are actually responsible for a molecules colour) that absorb photons/light from the red and near infra-red light wavelengths and cause electrons to jump into a higher energy orbit. This extra energy produced in the mitochondria can therefore be used for cellular processes throughout the body and can increase cellular metabolism by up to 200%.

Research also indicates that the light photons from the RLT are also absorbed by Cytochrome c oxidase (CcO), a respiratory enzyme in the mitochondria that is essential for producing ATP (energy). When CcO absorbs these light wavelengths, Nitric Oxide (which builds up in our mitochondria due to toxins in our environment and inhibits the energy production process) is released from the CcO, enabling the mitochondria to make more ATP so that more energy is available for all biological process - growth, repair and cell specific functions. This process also serves to strengthen and grow mitochondria (which decrease in number and become less effective as we age), thus having an overall impact on health and longevity.

Red and near infrared light also enhances the production of basic fibroblast growth factor, increasing the growth and numbers of fibroblasts (a type of cell that produces collagen) and therefore improving skin and joint health and healing. It also effects factors that influence gene expression and protein synthesis, playing a role in cytokine modulation, muscle recovery, tissue repair and collagen formation, tissue oxygenation, liver regeneration, inflammatory mediators and central nervous system health (by increasing bone-derived neurotrophic factor). This is why RLT is popular for skin health and muscle and joint recovrey and repair.

From these processes there is a flow on effect that translates to all kinds of other benefits to our health including:

  • Improved muscle recovery after a workout

  • Improve sleep quality

  • Improve mental health by regulating stress response

  • Reduce joint pain

  • Improve thyroid health

  • Reduced inflammation and pain

  • Improve injury recovery

  • Improve skin tone and health

delayed onset muscle soreness

Delayed Onset Muscle Soreness and Muscle Performance

In a study comparing red light therapy and cryotherapy (cold therapy), red light therapy was estimated to improve muscle strength, 27%, reduce delayed onset muscle soreness, 87% and lower the concentration of biomarkers of muscle damage, 76%, compared to cryotherapy. (23)

A study of males between 20 and 30 years old who had red light therapy prior to a muscle fatigue induction protocol showed a less noticeable decrease in muscle strength, evidencing a lower rate of muscle fatigue than the control group. (24)

Body pain

Body Pain

Red light therapy has been shown to reduce pain immediately after treatment in acute neck pain and up to 22 weeks after completion of treatment in patients with chronic neck pain. (25)

A 2013 meta-analysis for 17 studies showed reduction in both acute and chronic neck pain and improved functionality measurements (such as range of motion) with low level laser red light therapy. (26)

A 2014 trial with Fibromyalgia patients evaluated red and near infrared laser light therapy three times per week for 4 weeks and showed marked improvement compared to placebo in physical impairment, work missed, pain, fatigue, stiffness, anxiety, and depression scores. (27)

These treatments are now available in two locations West Auckland

Inside Matters has partnered with the Waitakere Health Hub in Henderson and also have sessions available at a home Wellness Room in Glen Eden.

Waitakere Health Hub is a growing health clinic who believe that treating the whole body is the best way to heal, nourish and strengthen. Whether you are in pain, recovering from an injury, or just looking to improve your overall well-being, they can fully personalise a treatment plan to fit your needs and goals, providing osteopathy, acupuncture, massage, infrared sauna, red light therapy and a gym space for rehabilitation work, yoga and tai chi .

How to choose the best infrared sauna for your home

If you are looking to buy an infrared sauna for your home there are a few important things to consider. Its important to ensure the sauna you purchase has these things covered so that your sauna experience is beneficial to your health rather than harmful.

1. Low EMF / ELF

Electric fields are created by differences in voltage, and magnetic fields are created when the electric current flows. These can effect us as our bodies have their own electric and biochemical responses in our heart, brain, digestive and nervous system functions.

Choose high quality Nano Carbon heaters that emit virtually no EMF and have innovations that reduce ELF electric fields as well.

What's a low level of EMF? - Sun Stream Saunas emit less than 1mG (milliGauss) when measured from a distance of less than 1 inch from the heaters. For safety, The EPA (Environmental Protection Authority) recommends you limit your magnetic field exposure to less than 2.5mG. Their heaters also reduces ELF electric fields to near zero.

2. Hypoallergengic wood

It's critical that the sauna wood is 100% premium grade non treated Basswood or Hemlock or Redwood, so that its non toxic and doesnt have any harmfull off gases when heated. Some saunas will use these woods for the outside and a cheaper wood inside, so make sure its 100% safe wood.

3. Non toxic food safe glue

Make sure the sauna has been made with non toxic food safe glue. When its heats up you don't want any toxins breaking down and ending up in your bloodstream.

4. 360 degree heating panels

With heater panels on all sides of the sauna including the floor and door so its 360 degrees, this will provide a greater efficiency of radiant heat directly targeting your body, producing an enhanced sauna experience.

5. Infrared carbon panel heaters with testing procedures

Nano Carbon heating panels are very efficient at radiating far infrared heat. To ensure you are buying a sauna with a quality heater look to see if the company has testing procedures that allows you to visually gauge the amount of radiant heat from the heaters and ensure there is zero emittance of volitile organic compounds, which can be harmful to your health.

6. Residential lifetime warranty

Yes these are available and if you have a company that provides an infraed sauna with the above benefits and a lifetime warranty then you're set!


I have done a lot of research and love my Sun Stream Sauna. The team at Sun Stream are great, super helpful and have the best value for money infrared sauna's on the market. In addition their sauna's are sustainable hypo-allergic basswood with top quality nano-carbon heaters and they use food-safe non-toxic glues.

While one of the benefits of infrared sauna's is that you can sweat and get the same benefits of a traditional sauna at a lower temp for those who like it super hot, Sun Stream Saunas have the heat intensity if you want it also.

Sun Stream Infrared Sauna

They have a range of sizes to suit your space, are made with premium materials and workmanship and a residential lifetime warranty.

Check out the Sun Stream range here and receive a special discount when you purchase through this link or mention my name.


1. JA; LTKHZFL. Association between sauna bathing and fatal cardiovascular and all-cause mortality events [Internet]. JAMA internal medicine. U.S. National Library of Medicine; [cited 2022Feb14]. Available from:

2. Kanji G;Weatherall M;Peter R;Purdie G;Page R; Efficacy of regular sauna bathing for chronic tension-type headache: A randomized controlled study [Internet]. Journal of alternative and complementary medicine (New York, N.Y.). U.S. National Library of Medicine; [cited 2022Feb14]. Available from:

3. Kukkonen-Harjula K, Oja P, Laustiola K, Vuori I, Jolkkonen J, Siitonen S, Vapaatalo H. Haemodynamic and hormonal responses to heat exposure in a Finnish sauna bath. Eur J Appl Physiol Occup Physiol. 1989;58(5):543-50. doi: 10.1007/BF02330710. PMID: 2759081.

4. Jezová D, Vigas M, Tatár P, Jurcovicová J, Palát M. Rise in plasma beta-endorphin and ACTH in response to hyperthermia in sauna. Horm Metab Res. 1985 Dec;17(12):693-4. doi: 10.1055/s-2007-1013648. PMID: 3002937.

5. Vescovi PP, Coiro V. Hyperthermia and endorphins. Biomed Pharmacother. 1993;47(8):301-4. doi: 10.1016/0753-3322(93)90078-y. PMID: 8061252.

6. Masuda A;Koga Y;Hattanmaru M;Minagoe S;Tei C; The effects of repeated thermal therapy for patients with chronic pain [Internet]. Psychotherapy and psychosomatics. U.S. National Library of Medicine; [cited 2022Feb14]. Available from:

7. C; MKMAT. Efficacy of WAON therapy for fibromyalgia [Internet]. Internal medicine (Tokyo, Japan). U.S. National Library of Medicine; [cited 2022Feb14]. Available from:

8. Matsumoto S;Shimodozono M;Etoh S;Miyata R;Kawahira K; Effects of thermal therapy combining sauna therapy and underwater exercise in patients with fibromyalgia [Internet]. Complementary therapies in clinical practice. U.S. National Library of Medicine; [cited 2022Feb14]. Available from:

9. Masuda A;Kihara T;Fukudome T;Shinsato T;Minagoe S;Tei C; The effects of repeated thermal therapy for two patients with chronic fatigue syndrome [Internet]. Journal of psychosomatic research. U.S. National Library of Medicine; [cited 2022Feb14]. Available from:

10. Soejima Y;Munemoto T;Masuda A;Uwatoko Y;Miyata M;Tei C; Effects of WAON therapy on chronic fatigue syndrome: A pilot study [Internet]. Internal medicine (Tokyo, Japan). U.S. National Library of Medicine; [cited 2022Feb14]. Available from:

11. H; I. The sauna and rheumatic diseases [Internet]. Annals of clinical research. U.S. National Library of Medicine; [cited 2022Feb14]. Available from:

12. Jezová D, Vigas M, Tatár P, Jurcovicová J, Palát M. Rise in plasma beta-endorphin and ACTH in response to hyperthermia in sauna. Horm Metab Res. 1985 Dec;17(12):693-4. doi: 10.1055/s-2007-1013648. PMID: 3002937.

13. Kukkonen-Harjula K, Oja P, Laustiola K, Vuori I, Jolkkonen J, Siitonen S, Vapaatalo H. Haemodynamic and hormonal responses to heat exposure in a Finnish sauna bath. Eur J Appl Physiol Occup Physiol. 1989;58(5):543-50. doi: 10.1007/BF02330710. PMID: 2759081.

14. Tanjaniina Laukkanen, Jukka Lipponen, Setor K. Kunutsor, Francesco Zaccardi, Claudio Gil S. Araújo, Timo H. Mäkikallio, Hassan Khan, Peter Willeit, Earric Lee, Sanna Poikonen, Mika Tarvainen, Jari A. Laukkanen, Recovery from sauna bathing favorably modulates cardiac autonomic nervous system, Complementary Therapies in Medicine,

Volume 45, 2019, Pages 190-197, ISSN 0965-2299,


15. Masuda A;Nakazato M;Kihara T;Minagoe S;Tei C; Repeated thermal therapy diminishes appetite loss and subjective complaints in mildly depressed patients [Internet]. Psychosomatic medicine. U.S. National Library of Medicine; [cited 2022Feb14]. Available from:

16. Basford JR;Oh JK;Allison TG;Sheffield CG;Manahan BG;Hodge DO;Tajik AJ;Rodeheffer RJ;Tei C; Safety, acceptance, and physiologic effects of sauna bathing in people with chronic heart failure: A pilot report [Internet]. Archives of physical medicine and rehabilitation. U.S. National Library of Medicine; [cited 2022Feb14]. Available from:

17. Sears ME, Genuis SJ. Environmental determinants of chronic disease and medical approaches: recognition, avoidance, supportive therapy, and detoxification. J Environ Public Health. 2012;2012:356798. doi: 10.1155/2012/356798. Epub 2012 Jan 19. PMID: 22315626; PMCID: PMC3270432.

18. MC; RGHS. Methamphetamine exposure and chronic illness in police officers: Significant improvement with sauna-based detoxification therapy [Internet]. Toxicology and industrial health. U.S. National Library of Medicine; [cited 2022Feb14]. Available from:

19. Viktor Zinchuk, Dzmitry Zhadzko. Sauna effect on blood oxygen transport and prooxidant-antioxidant balance in athletes [Internet]. Medicina Sportiva, vol VIII, no 3, 1883 - 1889, Romanian Sports Medicine Society; 2012 [cited 2022Feb14]. Available from:

20. JD; SGSHWGMSC. Effect of post-exercise sauna bathing on the endurance performance of competitive male runners [Internet]. Journal of science and medicine in sport. U.S. National Library of Medicine; [cited 2022Feb14]. Available from:

21. Ahokas EK, Ihalainen JK, Hanstock HG, Savolainen E, Kyröläinen H. A post-exercise infrared sauna session improves recovery of neuromuscular performance and muscle soreness after resistance exercise training. Biol Sport. 2023 Jul;40(3):681-689. doi: 10.5114/biolsport.2023.119289. Epub 2022 Sep 15. PMID: 37398966; PMCID: PMC10286597.

22. MIETTINEN M, KARVINEN E. EFFECT OF SAUNA BATH ON PHYSICAL PERFORMANCE. J Sports Med Phys Fitness. 1963 Dec;3:225-8. PMID: 14099073.

23. Ferlito JV;Ferlito MV;Leal-Junior ECP;Tomazoni SS;De Marchi T; Comparison between cryotherapy and photobiomodulation in Muscle Recovery: A systematic review and meta-analysis [Internet]. Lasers in medical science. U.S. National Library of Medicine; [cited 2022Feb14]. Available from:

24. Stamborowski SF;de Oliveira Spinelli BM;Lima FPS;Costa DR;de Silveira Souza GA;Lima MO;Lopes Martins RAB; The influence of photobiomodulation on the temperature of the brachial biceps during muscle fatigue protocol [Internet]. Lasers in medical science. U.S. National Library of Medicine; [cited 2022Feb14]. Available from:

25. JM; CRTJMIL-MRAB. Efficacy of low-level laser therapy in the management of Neck Pain: A systematic review and meta-analysis of randomised placebo or active-treatment controlled trials [Internet]. Lancet (London, England). U.S. National Library of Medicine; [cited 2022Feb14]. Available from:

26. Gross AR, Dziengo S, Boers O, Goldsmith CH, Graham N, Lilge L, et al. Low level laser therapy (LLLT) for Neck Pain: A systematic review and meta-regression [Internet]. The open orthopaedics journal. Bentham Open; 2013 [cited 2022Feb14]. Available from:

27. RA; RJAFARRMBN. Low-level laser therapy to treat fibromyalgia [Internet]. Lasers in medical science. U.S. National Library of Medicine; [cited 2022Feb14]. Available from:


bottom of page