With a long tradition of use in countries like Finland, sauna use has in the recent years become somewhat more mainstream due to its many purported health benefits.
As a newer addition, infrared saunas have popped up in many health spas and clinics.
But are infrared saunas all they are hyped up to be? First, let’s look at what research has to say on the benefits of traditional sauna use.
Health benefits of sauna use and ‘hyperthermia’:
Regular long-term sauna bathing has been shown to
- Improve cardiovascular markers, such as blood pressure, inflammation, arterial stiffness, oxidative stress, lowering total and LDL cholesterol, increasing the protective HLD cholesterol and more.
- It further improves the parasympathetic (the rest-digest-and-heal) nervous system.
- It is associated with a reduced risk of cardiovascular disease mortality, stroke, dementia and pulmonary disease, as well as reduced all-cause mortality. (1)
- In athletes, it has been show to accelerate recovery, reduce incidence of delayed-muscle-soreness (DOMS) and speeds up healing after injury
- Decrease pain and improve mobility in rheumatoid arthritis and low back pain (2).
- In a meta-analysis, exposure to an infrared sauna bath in 60°C for 15 minutes, followed by a 30-minute rest in warm environment, five times a week for 2 to 4 weeks, was associated with a significant reduction in B-type natriuretic peptide, cardiothoracic ratio, and an improvement in left-ventricular ejection fraction, which are all measures of cardiovascular health (3)
- Another study demonstrates that a session of sauna bathing induces an increase in heart rate while in the sauna. During the cooling down period from sauna bathing, HRV increases which indicates the dominant role of parasympathetic activity and decreased sympathetic activity of cardiac autonomic nervous system (4).
- Increased levels of cardiorespiratory fitness and frequent sauna bathing are both each associated with a reduced risk of future pneumonia. one exposure is not a stronger risk indicator than the other and vice versa, but both have a synergistic effect on the outcome. These findings are consistent with previous findings on the joint associations of CRF and FSB on adverse vascular outcomes as well as all‐cause mortality. There have also been reports of substantial beneficial changes in cardiovascular function when PA is combined with sauna exposure (5).
- Regular sauna bathing has traditionally been used in Finland as a method of “hardening,” which means enhancing the body’s resistance. Frequent sauna sessions reduce the risk of respiratory tract infections, such as common colds and pneumonia caused by viral and bacterial infections via (a) direct inhibition of pathogens; (b) boosting both the innate and adaptive arms of the immune system; dampening of inflammatory responses; and (d) by having direct effects on lung tissue which include improvement in lung function and reduction in pulmonary congestion. Evidence suggests the adaptive responses produced by an ordinary sauna bath corresponds to that produced by moderate or high-intensity physical activity (6).
- In a population-based prospective cohort study, a combination of high cardiorespiratory fitness levels and frequent sauna bathing (3-7 sessions per week) was associated with a substantial risk reduction in fatal cardiovascular and all-cause mortality events compared with good cardiorespiratory fitness or frequent sauna bathing alone. A combination of good fitness levels produced by aerobic exercises and frequent sauna bathing may have added health benefits and confer more protection on the risk of mortality (7).
- Sudden cardiac death (SCD) is a global public health burden accounting for 15-20% of all deaths. Observational data suggest that regular sauna bathing is associated with a substantial risk reduction in SCD. Furthermore, the data suggest that a combination of regular physical activity and sauna baths confers substantial risk reduction for SCD compared with either modality alone.
- Sauna therapy may act to improve multiple chemical sensitivity, heart failure, endothelial dysfunction, chronic fatigue and fibromyalgia via increasing tetrahydrobiopterin (8).
- Physiologists have long regarded sweating as an effective and safe means of detoxification, and heavy metals are excreted through sweat to reduce the levels of such metals in the body. Sweat samples were collected from the participants while they were either running on a treadmill or sitting in a sauna cabinet. After they experienced continuous sweating for 20 min, a minimum of 7 mL of sweat was collected from each participant. The results demonstrated that the sweating method affected the excretion of heavy metals in sweat, with the concentrations of Ni, Pb, Cu, and As being significantly higher during dynamic exercise than during sitting in the sauna. However, the concentrations of Hg were unaffected by the sweating method (9).
Infrared saunas – how do they work, and what are their (added) health benefits?
Great, you may say, but what’s the point in infrared saunas?
Rather than heating the body up from the outside, like traditional saunas, infrared saunas heat the body up from the inside out. This allows the surrounding air to stay at a lower temperature (usually around 60 degrees C), making infrared saunas not only a more comfortable experience to people struggling with the high heat of traditional saunas, but also have a few added perks.
Far infrared saunas induce sweating at much lower temperatures as traditional saunas, which brings added benefit in comparison to the hotter variety.
- It is more comfortable, and as such can be used for longer, resulting in deeper cellular stimulation.
- It allows for a gentler experience, in particular for individuals with a history of heart problems or for some other reason would prefer not to put their body through the extreme heat
- The high heat of traditional saunas carry with them the risk of skin ageing, lung and eye damage due to their very high temperatures. These are mitigated with infrared saunas, giving you all benefits without potential downsides.
But first things first, what actually are infrared saunas? Infrared is a type of rays naturally emitted by the sun. It is invisible to the eye, and many of the sunlight’s healing properties can be linked back to its infrared rays.
There are 3 types of infrared, near, mid and far infrared, each distinguished by different wave lengths and benefits to the body.
Far infrared rays (FIR), the most commonly used type in commercial saunas, don’t as such penetrate very deep into the body. However, as they heat up the body’s water, their effect reaches into all cells and provokes a deep, cleansing sweat, from the inside out (10).
Infrared saunas have been shown in studies to elicit very similar health effects as traditional saunas, at lower and safer temperatures (see above list). Yet far infrared light has been shown to have their own unique set of additional benefits, making this a potentially much more powerful tool to add to your health optimisation box. Research suggests it:
- May help suppress cancer cells (11).
- A study by Ryotokuji et al. indicated that four weeks of far infrared radiation administered to the feet of type 2 DM patients significantly reduced cortisol levels and blood glucose levels (12).
- Lowered cortisol and blood sugar levels help reduce that detrimental abdominal (belly) fat
- A 3-month program ameliorated the severity of frailty and frailty related indices in older Japanese people (13).
- FIR sauna therapy has been used to improve cardiac and vascular function, peripheral arterial disease, and reduce oxidative stress in patients with chronic heart failure (14).
- A study of patients with rheumatoid arthritis and ankylosing spondylitis showed a reduction in pain, stiffness, and fatigue during infrared sauna therapy.
- It has been shown to reduce symptoms of exercise-induced muscle damage in athletes, help with chronic kidney disease, stress, and depression.
- It may help with obesity. In a study, 10 obese subjects underwent 15-minute daily FIRS sessions and followed an 1800 calorie per day diet for a 2-week period. Despite weight loss, plasma ghrelin and leptin concentrations did not change. Usually these hormones change during weight loss, affecting satiety and metabolism in a detrimental manner. The study concluded that infrared therapy could help loose weight by affecting these hormone and make weight loss ‘easier’ (15).
- Reduced facial wrinkles by increasing collagen and elastin content, improved skin texture and roughness. Therefore, skin treatment with infrared radiation may be an effective and safe non-ablative remodeling method, and may also be useful in the treatment of photo-aged skin (16).
- Ameliorates stressful condition, memory impairments, drug dependence, and mitochondrial dysfunction in the central nervous system (17).
- Reduced swelling, lymphedema (18).
- And lastly, far infrared light has been shown to reduce period cramps (19).
- Exposure to FIR stimulates oxygenation and sweating within the body which might be essential for detoxification and elimination of impurities (20).
I am not sure about you, but I am sold :)!
Some newer companies offer added near and mid infrared technologies.
Over the last ten years, there has been an assemblage of animal studies focusing on the use of transcranial near-infrared light therapy (NILT) to treat brain injury from stroke or trauma.
At its shortest wavelengths (referred to as near-infrared), it merges with the red spectrum of visible light. At the longest end (referred to as far-infrared), it blends into the range of microwaves.
Short IR is proposed to be absorbed by cytochrome c oxidase in mitochondria https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5505738/
Mid infrared light has not been studied much yet.
We found that APP/PS1 mice treated with MIR light had improved learning and memory abilities and reduced amyloid-β (Aβ) plaque load in the brain. We also surprisingly found that the gut microbiota composition in APP/PS1 mice treated with MIR light returned to normal (wild type mice) levels. Together, these findings suggested a novel non-invasive and promising avenue for AD treatment via photobiomodulation, and also proposed that future target for AD might be the gut microbiota via the brain-gut-skin axis.
Another study published in 2021 in Nature showed that stimulation with mid infrared activated brain neurons and accelerated learning. However, this study was done on mice with both an opened and thinned skull, and more studies are needed to confirm if these results can be translated into humans with intact skulls. https://www.nature.com/articles/s41467-021-23025-y