Committed to health and wellness, many individuals follow their heat therapy protocol religiously. Following the advice of many studies, experts, and influencers, those who care deeply about their health may be getting into their sauna, hot tub, or steam room anywhere from three to seven times per week. As many people have experienced there is an adaptation period for climatic, seasonal, or temperature change, which means simply that the body can get used to different temperatures.
So, if heat therapy is based on the premise of hormesis (positive stress) does it continue to apply enough healthy stress on the body to be an effective healing tool after long-term consistent use?
Can the body become so accustomed to sauna heat that it can eventually fail as a health positive activity? A close examination into the bio-chemical reaction to heat over a long period of time is necessary to figure out the answer to this question. Furthermore, understanding how different body parts, organs, and systems respond to heat will tell a more detailed story about long term sauna use or heat therapy.
In early 2026 a collective of seven scientists organized a meta-analysis on a collection of the most relevant and revered studies on heat therapy to better understand the effects of long-term heat therapy versus shorter bouts of exposure to intentional passive heat.
The broad strokes of this meta-analysis relay the various styles of heat therapy in great deal, with an offering of comparisons between the different modalities. Additionally this literature attempts to reveal if adaptation to heat negates the benefits of heat therapy.
The results of this analysis are nuanced and dependent upon the essential nature of the human thermoregulatory system to stabilize internal temperature every day and at every moment of every day for the entirety of a human’s life.
You may discover that, like brushing your teeth, showering, and sleeping, there are some things that are best done daily, or nearly daily; sauna use may be among these!
Does Heat Adaptation Negate the Hormetic Effect From Sauna Bathing?
Though humans have turned to heat therapy for thousands of years, the great popularization of sauna use has exploded in the last forty years. In conjunction with an increase in popularity there has also been an increase in documentation, research, studies, and papers published on the subject of heat therapy. Or perhaps the increase in popularity was a result of an increase in scientific interest in the therapeutic benefits of heat therapy. Either way, more people are using saunas today more than ever before.
A paper published by the National Library of Medicine in January of 2026 entitled ‘Does Heat Therapy Cause Long‐Term Adaptations in the Human Body?’ seeks to explore and analyze 439 different studies on heat therapy and human physiology. The seven authors of this paper go through a very lengthy meta-analysis of the research on heat therapy and its long-term effects on humans.
The authors begin by giving a brief history of the ancient use of thermal therapy but express that their primary interest is in the research that has occurred over the past forty years.
“Over the last ~40 years, heat therapy has gained increasing popularity among scientists and clinicians as a potential therapeutic tool for aging and disease.” (1)
With much research in this field determining that it is best to sauna often, at least 3-7 times per week, the authors investigated whether the eventual adaptation to heat would reduce the health benefits with high frequency exposure. This meta-analysis is extremely lengthy, so the focus here is simply on the sections that examine heat therapy and physiological adaptation.
To understand heat therapy one must first know its hormetic effect on humans. Some describe the hormetic effect or hormesis as ‘positive stress’ placed on the body. According to a paper published by the National Library of Medicine entitled ‘Hormesis Defined’, the hormetic effect is well defined by its authors here.
“Thus, a short working definition of hormesis is: ‘a process in which exposure to a low dose of a chemical agent or environmental factor that is damaging at higher doses induces an adaptive beneficial effect on the cell or organism’.” (2)
If the body is continuously exposed to the same hormesis does it eventually adapt and is the hormetic effect therefore negated? This seems like a really great question, but when activities such as exercise are considered, there appears to be a need for fairly regular increases of stress on the body from certain activities and environments in order to maintain a healthy increase in benefit.
To some extent the body will adjust to a positive stress, but this does not mean that the positive stress ceases to have a positive impact on the body. This is true for exercise, but with exercise a person can continue to increase the weight load, for example, or speed or distance, to continue to accrue more stress on the body, so should the same be true for heat therapy? Actually, surprisingly, no.
While there is certainly a period of adjustment and acclimatization to the heat of a sauna over a period of weeks, and it may become easier to stay in the sauna for longer, or at higher temperatures, the reality is that humans become better at stabilizing their internal temperature by becoming better at perspiration. What does this mean? It means that the body must maintain an internal temperature that stays within a very small range. In order to do this the body must harness the cardiovascular system and physiological molecular changes to maintain a safe internal temperature.
These responses from the thermoregulatory system are elicited each and every time the body is exposed to higher or lower external temperatures. Therefore, the body’s adaptation to heat therapy is continuous. In short, every time that the body must regulate temperature and must continue to elicit both a molecular release, as well as a cardiovascular engagement.
Unlike other forms of hormesis, thermal stress continues to affect human physiology even with consistent and regular exposure. Unlike the body’s ability to continue to develop muscle to bear more weight, the body will never be able to safely increase in body temperature beyond a few degrees, and herein lies the crux of the difference between heat stress and many other forms of hormesis.
Cellular and Molecular Response to Heat Therapy: Heat Shock Proteins, Reduction in Oxidative Stress, Anti-inflammatory Cytokines
Every single time the body increases in temperature and the thermoregulatory system is enlisted, crucial aspects to health such as the release of Heat Shock Proteins (HSPs) will occur. Molecular changes to heat must occur every time that heat stress is applied to the body in order to maintain a healthy internal temperature. Therefore, there will not be a time when the body is fully acclimated to this style of hormesis.
The authors of the meta-analysis explored earlier ‘Does Heat Therapy Cause Long‐Term Adaptations in the Human Body?’ (1) describe how heat effects all aspects of human physiology here, including the molecular level.
“This is, in many ways, similar to exercise, in which every cell in the body can undergo a hormetic stress when the whole‐body or core temperature is elevated. Multiple inflammatory, hormonal, and blood‐borne signals that are often released from specific tissues, such as skeletal muscle, may work to allow communication between the organ systems”. (1)
A key aspect that is unchanging regardless of how many years an individual has been consistently using a sauna is the release of heat shock proteins. These mighty but tiny aspects of human physiology are described and defined by the authors here.
“This family of stress proteins and chaperones is expressed by all cells throughout the body and functions to maintain normal protein folding and protect against cellular stress. Each HSP is classified according to its molecular weight in kilodaltons, with the most studied families being HSP60, HSP70, and HSP90.” (1)
HSPs are responsible for many different functions, but one key aspect is maintaining a healthy intracellular space. By folding proteins and escorting them safely to their destination, HSPs help to protect against cellular stress. HSPs help to defend against oxidative stress by maintaining a clean and safe intracellular environment. (1)
Furthermore HSPs can help ensure the high function of both the innate and adaptive immune system, regulate insulin sensitivity, reduce oxidative stress, regulate the life-death cycle of cells by up-regulating cellular metabolism. (3)
Each and every time the body is exposed to extreme heat for a limited period of time HSPs are released. In addition to this, each time there is appropriate heat stress on the body anti-inflammatory cytokines are released. (1)
Chronic inflammation is a serious issue for many individuals, particularly for the aging population. Heat exposure affects the molecular constitution of the body and helps by releasing anti-inflammatory cytokines to reduce chronic inflammation. This does not occur one time or just several times, but every time that an individual is engulfed in time and temperature appropriate full body heat therapy.
It appears that for many aspects of human health it is important to continue to engage in heat therapy regularly, and that this is especially true for the molecular changes that occur in response to heat therapy for cellular protection and inflammation reduction.
Heat Therapy and Cardiovascular Health: Maintenance After Growth
Saunas reduce ‘all-cause mortality’ was the slogan for many years to get more people into saunas. This statement was based on the famous study of a large group of Finnish men over the course of decades that found that saunas improved cardiovascular health so tremendously that it lessened the chance of dying from a heart related disease. Cardiovascular death is the most common way that humans die. By decreasing this number, the statement ‘reduction of all-cause mortality’ can be claimed. What is interesting about the origin of the statement is that it was found in the research on the Finnish men that the more frequently an individual took a sauna session the better their cardiovascular health would be, for example, 4-7 times per week instead of 2-4 times per week.
Few individuals in the world of saunas and heat therapy are unfamiliar with the epic study of the Finnish men and the results for cardiovascular health. Published in Medical Science, the paper entitled ‘Finnish Sauna Bathing in Cardiovascular Health: Mechanistic Insights, Mortality Benefits, and Safety Considerations for At-Risk Populations’ (6) describes some of the findings on cardiovascular health from this famous study.
“Longitudinal cohort studies demonstrate that frequent sauna use (4–7 sessions/week) lowers incident hypertension risk by 47% (HR: 0.54, 95% CI: 0.32–0.91) and reduces sudden cardiac death risk by 63% (HR: 0.37, 95% CI: 0.18–0.75) via mechanisms including enhanced endothelial nitric oxide bioavailability, peripheral vasodilation, and improved-autonomic regulation. Synergistic interactions with cardiorespiratory fitness further enhance the benefits, with high fitness levels combined with frequent sauna use being associated with 69% lower cardiovascular disease (CVD) mortality.” (6)
Regular use of a sauna (4-7) times per week can help improve and maintain cardiovascular health in demographics that are already very aerobically fit as well as for those new to the exercise game. Of course, a well seasoned long distance runner will not respond in the same way to their first sauna as someone who has lived a mostly sedentary life.
In fact, the fitness gains for the sedentary individual will be far more dramatic than for the individual who is already very aerobically fit. So, unlike the molecular changes in the face of heat stress, cardiovascular ‘gains’ will be less obvious the more an individual uses a sauna. Nevertheless, the data still show that maintaining a sauna routine over the course of decades, that includes 4-7 sauna sessions per week, does in fact improve cardiovascular health.
While evidence of heat adaptation is seen more easily on the cardiovascular front, exposure to heat stress does seem to continue to have a strong positive impact on health even for those who are already aerobically fit as evidenced by the most illustrious sauna study ever conducted.
Include Sauna Into Your Regular Routine and Continue to Benefit For a Lifetime
After a careful review of the evidence it appears that adaptations to regular heat exposure does not negate the health benefits. Due to the unique thermoregulatory system of human beings the process of response to heat continues to elicit healthy biochemical responses as well as cardiovascular ones. So, if you are someone who saunas regularly and are worried that you are too used to the heat, then you can put those fears to rest.
Like anything, it is possible to over due sauna use or heat therapy. Make sure that you are not using your sauna more than 4-7 times per week, and that you maintain healthy levels of hydration at all times. Furthermore, there is benefit from resting from any activity, regardless of how healthy it may be. Take a few weeks off of your sauna every year for vacation, or during very hot days in the summer, but fear not continuing to sauna regularly.
The health benefits derived from sauna use will become available by the very nature of the human thermoregulatory system and cannot be over done if you respect the heat and your body. There are some exceptions to this, for example, if you are working on increasing Human Growth Hornome, in which case it is best to follow a specific protocol for this. If you are a male currently trying to conceive, or if you are an athlete with specific performance needs and goals.
For the most part, consider sauna use to be something like going for walks, brushing your teeth, and showering. Sauna use is a part of your health hygiene protocol and is not a one shot deal, but rather a part of your healthy lifestyle!
If you have specific health concerns, please speak with your medical provider before beginning your sauna protocol.
Sources Cited:
- https://pmc.ncbi.nlm.nih.gov/articles/PMC12819961/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC2248601/#:~:text=Thus%2C%20a%20short%20working%20definition,on%20the%20cell%20or%20organism
- https://pmc.ncbi.nlm.nih.gov/articles/PMC9345296/
- https://pubmed.ncbi.nlm.nih.gov/23509213/
- https://discoveryjournals.org/medicalscience/current_issue/v29/n161/e114ms3604.pdf#:~:text=Finnish%20sauna%20bathing%2C%20a%20traditional%20practice%20involving,bioavailability%2C%20peripheral%20vasodilation%2C%20and%20improved%20autonomic%20regulation.
- https://discoveryjournals.org/medicalscience/current_issue/v29/n161/e114ms3604.pdf#:~:text=Finnish%20sauna%20bathing%2C%20a%20traditional%20practice%20involving,bioavailability%2C%20peripheral%20vasodilation%2C%20and%20improved%20autonomic%20regulation.