The benefits of sauna
In a nutshell
Two types – heated traditionally and heated by infra-red light (potentially more beneficial)
Benefits – general health, lower heart disease and dementia leading to improved longevity
Frequency – as few as 2-3 sessions/week provide significant health benefits
Saunas are essentially small rooms heated to high temperatures. In this post I’ll summarise what I know about the following:
Types of sauna
Benefits of sauna
Sauna conditions to achieve benefit
Types of sauna
There are two types of sauna, traditional and infrared (IR) [1,2] (Table 1). Steam rooms may feel different, but they are essentially traditional with much added steam.
The traditional sauna uses an oven as a heat source, it can heat the air to a relatively high temperature, and provides the benefit of high humidity, acting as a steam room, if you enjoy that kind of thing. The IR sauna, on the other hand, uses IR light which penetrates the skin and reaches the blood and tissues. The IR sauna operates at lower temperatures to provide similar benefit and this can be useful for people who don’t enjoy higher temperatures.
Table 1: Operating conditions and their results for types of sauna
Benefits of sauna
Sauna increases our heart rate, blood circulation, core temperature, and production of things like heat shock proteins (HSP). The increased sweating as we try to cool down can result in expelling certain toxins. Long-term sauna use has been shown to be associated with improved sleep, improved insulin sensitivity, strengthened immune system, killing disease-causing infections, reduced risk of heart disease and dementia and even lower all-cause death [1,2,3,4].
Table 2: Benefits of sauna use
Increased heart rate, blood circulation, and core temperature
Sauna mimics some aspects of moderate cardiovascular exercise and results in things like increased blood flow to the skin and muscles, greater plasma volume, and higher heart rate. This explains some of the cardiovascular and brain-associated benefits of the sauna.
Heat shock proteins
Let’s put this subject in the context of how our species evolved. It is believed that the ageing process involves the gradual accumulation of damaged genetic material, proteins and other substances. This happens because our repair and maintenance at a molecular level, isn’t perfect and our bodies make mistakes. To counter this in-built imperfection, we have evolved a repair mechanism that kicks in when we are exposed to things like exercise and mild heat stress.
One of the things that happens when we are exposed to heat stress is to produce heat shock proteins. These proteins are involved in a process that prevents the age-related accumulation of damaged proteins. HSP help to repair lightly damaged proteins and clear out badly damaged proteins and in so doing, contribute to increased longevity [5].
Expelling toxins
The literature has many references to how sauna helps to expel toxins. I used two well-referenced books [1,2] as my sources. Toxins can be natural or man-made, and can be introduced from outside our body or produced internally. External toxins may include those from mold and other fungi, metals, pharmaceuticals, plastic components, and processed food. Toxins generated within our bodies may include those from infectious agents and the breakdown products of pharmaceuticals, processed food, and other man-made chemicals that we were exposed to.
Sauna helps us eliminate toxins by heating the body, increasing blood flow to the skin, and sweating. Those responses to heat help to move toxins from our insides to our skin where they are eliminated in our sweat.
I personally have never thought that toxin elimination helps me personally but it wouldn’t be the first time if I was wrong about that too…! There is so much information published on the subject that I’d be remiss not to include it here.
Exercise recovery
Sauna appears to lower the inflammation caused by exercise and inhibit muscle soreness [7]. This appears to be especially useful when strength training (lifting weights).
The benefits of sauna in this context may be two-fold. Blood flow is increased to the muscles being repaired post exercise and growth hormone appears to be increased. The latter stops the breakdown of protein and supports new muscle growth [6].
Improved sleep
I’ve found that my sleep has somewhat improved since I started using a sauna. I haven’t taken the time to figure out why because the effect for me is not great. I mostly use the sauna in early evening and the benefit may be that as I cool down afterwards, it mimics my body’s natural pre-sleep cooling process.
Improved insulin sensitivity
Being sensitive to insulin is a vital component of a healthy metabolism, and insulin insensitivity can lead to all manner of so-called chronic diseases. Saunas improve insulin sensitivity by increasing the clearance of blood sugar (glucose) into our muscles where it may be stored safely as glycogen [1].
Strengthened immune system and reduction in infections
Raising body temperature increases the number and effectiveness of immune system cells and induces HSP production. In so doing, sauna appears to help prevent infections and fight them if they do take hold.
The increased number and effectiveness of immune cells all create an anti-viral effect. HSPs inhibit viral replication and prevent harmful chronic inflammation [1].
As a younger man, I suffered regularly from seasonal viral and secondary respiratory infections. I am aware that I now suffer from fewer of those and I never contracted Covid. I can’t say with any sort of certainty that sauna use was the cure, but it has likely helped.
Reduced risk of heart disease
A Finnish study of middle-aged men found that:
“…sauna bathing is a protective factor against the risk of [death from heart disease] and all cause mortality events in the general male population.”
The study found that maximum benefit was provided by four to seven saunas per week in sessions lasting 19 minutes or longer [3].
Reduced risk of dementia
In another Finnish study of middle-aged and older men [4], sauna sessions of two to three, and four to seven days per week were associated with lower incidences of dementia and Alzheimer’s disease.
The authors stress that the causes of dementia in its various forms may be many and varied. However, they describe the associations between dementia and general properties such as heart rate, blood pressure and blood circulation. Dementia appears to be lessened as these factors are increased. Given that sauna use increases things like heart rate, blood pressure and blood circulation, it might be expected that sauna use is associated with decreased risk of dementia.
Improved mitochondrial function
The fact that our cells and their components are influenced by light was news to me. Apparently this is yet another example of my long-held ignorance. In 1999, it was written [7] that:
“…since light (especially red light) can penetrate deep into human tissues, and since absorbed light can cause photochemistry, it is appropriate to be concerned with the biological consequences of such absorbed light in the tissues of man.”
In other words, light penetrates into our body where it interacts with molecules that derive energy from it to initiate other biochemical reactions. Those biochemical reactions can improve the metabolism and health of our cells [7]. Our mitochondria are an important site of the light-accepting molecules.
Infrared saunas are capable of delivering the light that can penetrate us and provide the benefits that result.
Reduced all-cause death
It stands to reason that by improving things like exercise recovery, insulin sensitivity, immune function, and mitochondrial health and decreasing the incidence of heart disease and dementia, that a measure of all cause death is improved. Whilst the probability of death is 100%, sauna appears likely to affect longevity and delay the final reckoning.
Sauna Conditions to Achieve Benefit
The sauna I use is set at 80C (176F).
Sauna effects have been described as occurring in two phases [6]. In the first phase we start to heat up, sweat, and our heart rate increases. In the second phase, we improve our chances of HSP production and benefits to our cardiovascular and brain health.
I have tried to show this in Figure 1 in which I represent the first phase occurring within 10-15 minutes and the second phase thereafter.
I typically use the sauna between five and seven days each week for between 20 and 25 minutes each session. The duration of my sessions is exposing me to both phases, including the heart-health, immune system and HSP benefits (Figure 1). The frequency of my sessions seems to be well within the optimal exposure range [1].
Figure 1: Timeline showing the emergence of sauna health benefits
Summary
I started to use a traditional sauna a couple of years ago as part of my healthier lifestyle after retiring. Prior to that, through lack of awareness and my professional schedule, it didn’t occur to me to incorporate it therapeutically into my lifestyle.
Now I think I benefit from the schedule I’ve developed. I definitely feel the sleep benefits and suspect that I’ve strengthened my immune system. I can also report that after every session I have a sense of “reset” or “centering”. I don’t know how else to describe it, it’s not relaxation because I often enter a session quite relaxed.
The little I’ve read about the added benefits of IR sauna has fascinated me and I will try to find out more. I suspect there’s much more to the health story around skin-penetrating light. If nothing else, it’s another reason to be healthy enough to expose ourselves to the benefit of natural sunlight associated with Vitamin D production.
I’ll leave you with this. Knowing what I do now, I’d have made more of an effort earlier to use a sauna when I could have. Researchers have shown that frequencies of two to three and four to five times per week provide significant health benefit [1]. I could have achieved this in some of the larger hotels I stayed in for work and on Friday-Sunday evenings when I was at home. We live and learn.
References
Dinicolantonio, D. and Land, S. (2021) The Mineral Fix ; How to optimize your mineral intake for energy, longevity, immunity, sleep and more. John Wiley & Sons
Wilson, L. (2019) Sauna Therapy for Detoxification and Healing. www.drlwilson.com
Laukkanen T, Khan H, Zaccardi F, Laukkanen JA. Association between sauna bathing and fatal cardiovascular and all-cause mortality events. JAMA Intern Med. 2015 Apr;175(4):542-8. doi: 10.1001/jamainternmed.2014.8187. PMID: 25705824.
Tanjaniina Laukkanen, Setor Kunutsor, Jussi Kauhanen, Jari Antero Laukkanen, Sauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish men, Age and Ageing, Volume 46, Issue 2, March 2017, Pages 245–249, https://doi.org/10.1093/ageing/afw212
Rattan SI. Hormetic modulation of aging and longevity by mild heat stress. Dose Response. 2006 May 22;3(4):533-46. doi: 10.2203/dose-response.003.04.008. PMID: 18648625; PMCID: PMC2477195.
Dinicolantonio, D., Land, S. and Kennedy, T. (2021) Win: Achieve peak athletic performance, optimize recovery, and win. John Wiley & Sons
Karu T. Primary and secondary mechanisms of action of visible to near-IR radiation on cells. J Photochem Photobiol B. 1999 Mar;49(1):1-17. doi: 10.1016/S1011-1344(98)00219-X. PMID: 10365442.