AFTER CANCER: CAN HEAT HELP THE BODY RECOVER?

The Emerging Role of Thermotherapy in Cancer Rehabilitation and Survivorship

Written by: Daniel Root. Edited by: Lennard Goetze, Ed.D

Completing cancer treatment is an extraordinary milestone. Yet for many survivors, the end of treatment does not mean an immediate return to the health, strength or physical resilience they had before cancer. Surgery, chemotherapy, radiation, immunotherapy and hormonal therapies can leave lasting effects. Fatigue, muscle weakness, cardiovascular changes, altered metabolism, sleep disruption, reduced mobility, loss of conditioning and emotional stress may continue long after active treatment has ended. This has helped redefine the modern concept of cancer survivorship.

The objective is no longer simply to monitor for recurrence. Increasingly, survivorship care asks a broader question: How do we help the person who survived cancer recover health, function and quality of life?

Exercise and rehabilitation are already important parts of that conversation. But another intervention deserves thoughtful scientific consideration: thermotherapy—the controlled use of heat to produce physiological effects.

Heat has been used therapeutically for centuries. Modern research, however, allows us to examine something earlier generations could not: what controlled heat actually does to circulation, cardiovascular function, metabolism, muscles, the autonomic nervous system and even cellular stress responses. For cancer survivors, these effects raise several important possibilities.

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PART I: REBUILDING THE BODY

1. Cardiovascular Conditioning When Exercise Is Difficult

Physical activity is an important component of recovery, but some survivors emerge from treatment too fatigued or deconditioned to immediately tolerate meaningful exercise. Passive heat does not replace exercise. It does, however, produce some exercise-like physiological responses.

As body temperature increases, heart rate rises, blood vessels dilate and blood flow is redistributed toward the skin. These changes increase cardiovascular activity without requiring the muscular workload of conventional exercise.

This makes thermotherapy potentially interesting as an adjunct to progressive physical reconditioning, particularly during periods when conventional exercise remains difficult.

2. Supporting Vascular Health and Circulation

The endothelium—the cellular lining of blood vessels—plays a critical role in regulating circulation and cardiovascular health.

Heat promotes vasodilation, meaning that blood vessels widen and peripheral circulation increases. Repeated passive heating has therefore been studied for its potential effects on blood pressure, vascular function and endothelial health.

The evidence is not uniform, and that distinction is important. Temperature, duration, frequency, method of heating and individual health status can all influence the physiological response. For cancer survivors, the subject is particularly relevant because some cancer treatments can have lasting cardiovascular consequences.

3. Muscle, Mobility and Physical Reserve

Loss of muscle mass, strength and conditioning can occur during illness, treatment and prolonged inactivity. Heat increases muscle temperature and influences circulation, muscle contraction and several cellular processes associated with adaptation. Emerging research suggests that passive heating may have effects on neuromuscular function, although much of this work has been conducted outside cancer-survivor populations.

Thermotherapy cannot replace resistance exercise. The more meaningful question is whether heat, when combined with appropriately prescribed rehabilitation and exercise, may help selected survivors rebuild physical reserve.

4. Stiffness, Discomfort and Mobility

Therapeutic heat has long been used in physical rehabilitation for muscle and joint discomfort.

Increasing tissue temperature changes local circulation and muscle properties. For survivors experiencing stiffness, reduced mobility or the consequences of prolonged inactivity, controlled heat may therefore complement physical therapy, stretching, mobility work and exercise. The key word is complement. Cancer recovery is unlikely to be optimized by any single intervention.

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PART II: RECOVERING INTERNAL BALANCE

 

5. Metabolic Health After Cancer

Survivorship increasingly involves more than monitoring for recurrent disease. Body composition, glucose regulation, cardiovascular risk, blood pressure and the metabolic consequences of reduced activity or cancer treatment can all become part of long-term health management.

Passive heating is being investigated for effects on several of these cardiometabolic systems. Results remain mixed. Some studies report improvements in selected measures, while others show limited or no significant change. For that reason, thermotherapy should not be described as a treatment for metabolic disease. It is more appropriately regarded as a developing research area with potential relevance to survivorship.

6. The Autonomic Nervous System

Cancer is both a physical and psychological stressor. Diagnosis, uncertainty, treatment, pain, disrupted sleep and prolonged emotional stress can influence the autonomic nervous system—the system that helps regulate heart rate, blood pressure, digestion, recovery and the body's response to stress.

Researchers can examine this system through measures such as heart-rate variability, or HRV. Studies of sauna exposure have demonstrated measurable changes in HRV and autonomic activity during and after heat exposure. This provides an objective way of investigating something often described much more simply as “relaxation.”

Could appropriately administered thermotherapy become one component of restoring healthier autonomic regulation after cancer? The answer has not been established. But importantly, it can be scientifically tested.

7. Stress, Mood and Emotional Recovery

Recovery from cancer cannot be separated neatly into “physical” and “emotional” categories. Stress, sleep, mood, fatigue and physical function continually interact.

Whole-body hyperthermia has even been studied experimentally in psychiatric research, including clinical investigation of depressive symptoms. Those findings should not be interpreted to mean that sauna treats depression in cancer survivors. They do suggest, however, that the sense of relaxation or restoration associated with heat exposure may involve measurable physiological processes.

For someone recovering from one of life's most demanding medical experiences, emotional recovery and quality of life are not secondary outcomes. They are part of survivorship.

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PART III: THE BIOLOGY OF HEAT

8. Heat-Shock Proteins and Cellular Adaptation

Heat does considerably more than make the body feel warm. It creates a controlled physiological stress. One response is increased expression of heat-shock proteins, or HSPs. These proteins participate in cellular protection, protein maintenance and adaptation to stress.

This subject requires particular caution in cancer. Heat-shock proteins have complex roles in cancer biology, and their activation should not be interpreted as evidence that sauna prevents recurrence or treats residual cancer.

What the heat-shock response does demonstrate is that controlled heating produces genuine biological activity at both cellular and systemic levels. How those responses may contribute to rehabilitation and long-term health deserves further investigation.

9. Environmental Health, Sweating and the Detoxification Question

Environmental health is also becoming part of the broader survivorship discussion. Humans are continually exposed to substances through air, water, food, workplaces, consumer products and the built environment. Cancer survivors may additionally have complex histories of medications, therapeutic agents and medical procedures.

The body's principal systems for processing and eliminating unwanted substances involve the liver, kidneys, gastrointestinal tract and lungs. Sweat can also contain measurable quantities of certain environmental chemicals and elements. What remains uncertain is the clinical significance of sweating as an elimination pathway.

This distinction is essential. Sauna should not be presented as a mechanism that “cleanses” the body or replaces its natural elimination systems. A more scientifically responsible question is whether induced sweating, increased circulation, hydration, exercise and exposure assessment may eventually have complementary roles within carefully designed environmental-health strategies.

The evidence remains developing. That calls for better research rather than exaggerated claims.

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PART IV: HEAT AND CANCER MEDICINE

 

10. Medicine Already Uses Heat—But Not in the Same Way

There is an important distinction that is sometimes lost in discussions about thermotherapy. Medical hyperthermia and sauna bathing are not the same intervention.

Clinical hyperthermia is already used in oncology. Under carefully controlled medical conditions, tissue may be heated locally, regionally or throughout the body. Hyperthermia can be combined with other cancer treatments because heat can damage cancer cells and, in certain circumstances, increase tumor susceptibility to radiation therapy or chemotherapy.

A sauna does not reproduce these medical protocols and should never be represented as a treatment for cancer. What medical hyperthermia establishes is a more fundamental principle: Heat is biologically active.

The scientific questions are therefore not simply whether heat affects human physiology, but how much heat, delivered where, for how long, to which patient and for what therapeutic purpose. Those questions deserve consideration in cancer rehabilitation as well.

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THE SAUNA: AN OLD TECHNOLOGY WITH NEW QUESTIONS

Cardiovascular stimulation. Circulation. Autonomic regulation. Muscle recovery. Mobility. Metabolic health. Emotional well-being. Cellular adaptation. Induced sweating. These appear to represent very different areas of physiology.

Yet each can be influenced by one remarkably simple stimulus: Heat. And one of humanity's oldest methods of controlled heat exposure is the sauna. This does not mean sauna bathing treats cancer. It does not.

Nor should people undergoing cancer treatment begin intensive heat exposure without consulting their medical team. Cancer type and stage, cardiovascular health, medications, hydration, anemia, infection risk, recent surgery, radiation injury, lymphedema and other individual factors can affect whether thermotherapy is appropriate.

For the medically cleared survivor, however, perhaps we should move beyond the wrong question: “Can sauna cure cancer?” No. The more scientifically useful question is:

“Can controlled thermotherapy help the person who survived cancer recover some of what cancer—and its treatment—may have taken away?”

Strength. Cardiovascular reserve. Circulation. Mobility. Physical resilience. Autonomic balance. Emotional well-being. And ultimately, the ability to exercise, recover and participate more fully in life.

Cancer survivorship should encompass more than surveillance for recurrence. The goal is not merely to add years after cancer. It is to improve the health and quality of those years.

Thermotherapy will not accomplish that by itself. But an intervention capable of engaging multiple physiological systems involved in recovery deserves serious scientific attention—and considerably more rigorous investigation specifically among cancer survivors.

Sometimes an emerging area of medicine begins not with a new answer, but with a better question. In the evolving science of cancer survivorship, controlled heat may be one of those questions. This preserves what I think are the most important scientific guardrails in the original—especially that sauna is not cancer treatment, medical hyperthermia is distinct from ordinary sauna use, and individual clinical factors must determine whether thermotherapy is appropriate.

 

 

References

1. Brunt, V. E., Howard, M. J., Francisco, M. A., Ely, B. R., & Minson, C. T. (2016). Passive heat therapy improves endothelial function, arterial stiffness and blood pressure in sedentary humans. The Journal of Physiology, 594(18), 5329–5342. https://doi.org/10.1113/JP272453
2. Hannuksela, M. L., & Ellahham, S. (2001). Benefits and risks of sauna bathing. The American Journal of Medicine, 110(2), 118–126. https://doi.org/10.1016/S0002-9343(00)00671-9
3. Hussain, J., & Cohen, M. (2018). Clinical effects of regular dry sauna bathing: A systematic review. Evidence-Based Complementary and Alternative Medicine, 2018, Article 1857413. https://doi.org/10.1155/2018/1857413
4. Janssen, C. W., Lowry, C. A., Mehl, M. R., Allen, J. J. B., Kelly, K. L., Gartner, D. E., Medrano, A., Begay, T. K., Rentscher, K., White, J. J., Fridman, A., Roberts, L. J., Robbins, M. L., Hanusch, K.-U., Cole, S. P., & Raison, C. L. (2016). Whole-body hyperthermia for the treatment of major depressive disorder: A randomized clinical trial. JAMA Psychiatry, 73(8), 789–795. https://doi.org/10.1001/jamapsychiatry.2016.1031
5. Laukkanen, J. A., Laukkanen, T., & Kunutsor, S. K. (2018). Cardiovascular and other health benefits of sauna bathing: A review of the evidence. Mayo Clinic Proceedings, 93(8), 1111–1121. https://doi.org/10.1016/j.mayocp.2018.04.008
6. Ligibel, J. A., Bohlke, K., May, A. M., Clinton, S. K., Demark-Wahnefried, W., Gilchrist, S. C., Irwin, M. L., Late, M., Mansfield, S., Marshall, T. F., Meyerhardt, J. A., Thomson, C. A., Wood, W. A., & Alfano, C. M. (2022). Exercise, diet, and weight management during cancer treatment: ASCO guideline. Journal of Clinical Oncology, 40(22), 2491–2507. https://doi.org/10.1200/JCO.22.00687
7. National Cancer Institute. (2025, May 15). Hyperthermia to treat cancer. U.S. Department of Health and Human Services, National Institutes of Health. National Cancer Institute — Hyperthermia to Treat Cancer
8. Patrick, R. P., & Johnson, T. L. (2021). Sauna use as a lifestyle practice to extend healthspan. Experimental Gerontology, 154, 111509. https://doi.org/10.1016/j.exger.2021.111509
9. Pizzey, F. K., Smith, E. C., Ruediger, S. L., Keating, S. E., Askew, C. D., Coombes, J. S., & Bailey, T. G. (2021). The effect of heat therapy on blood pressure and peripheral vascular function: A systematic review and meta-analysis. Experimental Physiology, 106(6), 1317–1334. https://doi.org/10.1113/EP089424
10. Skorski, S., Schimpchen, J., Kühl, M., & Meyer, T. (2019). Effects of postexercise sauna bathing on recovery of swim performance. International Journal of Sports Physiology and Performance, 14(7), 934–940. https://doi.org/10.1123/ijspp.2018-0670
11. Wust, P., Hildebrandt, B., Sreenivasa, G., Rau, B., Gellermann, J., Riess, H., Felix, R., & Schlag, P. M. (2002). Hyperthermia in combined treatment of cancer. The Lancet Oncology, 3(8), 487–497. https://doi.org/10.1016/S1470-2045(02)00818-5

 

 

HEALTHTECH PERFORMANCE TEST DRIVE: THE FAR INFRARED SAUNA

Dr. Leslie Valle-Montoya’s Early Findings and Vision for Integrative Wellness (Relax Sauna)

August 18, 2026

For Dr. Leslie Valle-Montoya, the evaluation of the Relax Far Infrared Sauna began not with enthusiasm, but skepticism. As a clinical professional already experienced with infrared sauna therapy, she was accustomed to substantial wooden sauna systems used in both personal wellness and patient care. When the portable Relax Sauna arrived, its comparatively simple construction did not immediately suggest a technological advance.

Her first impression was candid: “I don’t like this. I feel this is a cheap version of another sauna.” She questioned whether a lightweight portable system could provide anything comparable to the larger infrared units she had already incorporated into practice. That skepticism, however, changed after she began using the device.

A Different Thermal Experience

The first practical distinction Valle-Montoya identified was efficiency. Unlike her larger sauna, the Relax system did not require a lengthy preheating period. Heat was apparent quickly after activation, while the operating temperature she cited was comparable to that of her wooden sauna—approximately 140°F. More important from a clinical workflow perspective was the shortened treatment period. In her experience, the portable sauna produced an intense thermal response within approximately 20–30 minutes, whereas longer sessions had traditionally been required with her conventional unit.

“If we can cut people’s time almost in half and still get the same or probably better benefit out of it,” she observed, “it is game changer.”

For a wellness practitioner, this is not simply a convenience issue. Treatment time affects patient compliance, scheduling, clinical throughput and the ability to combine thermal therapy with other components of a structured wellness program. A technology capable of generating a meaningful physiological response in a shorter period could potentially make regular sauna use more practical for patients who would otherwise resist a 45- or 60-minute commitment.

Valle-Montoya described the distinction in unusually clinical terms. Her traditional box sauna, she explained, was relaxing, soothing and beneficial. The Relax Sauna felt different to her—what she called “medicinal.” By that description, she was referring to the immediacy of the physiological experience: increased sweating, changes in heart rate and a sensation of active thermoregulation occurring considerably earlier in the session.

From Patient Experience to Measurement

Perhaps the most important feature of Valle-Montoya’s evaluation is that she does not want the assessment to end with subjective experience. Her larger clinical philosophy is based on an increasingly important question in integrative health technology: Can the physiological effects of a wellness intervention be measured?

At the time of the interview, she reported experience with approximately ten participants using the Relax Sauna, including individuals who had also used her conventional box sauna. Her developing evaluation model incorporates measures such as OligoScan assessment, heart-rate variability and other before-and-after indicators. She specifically described using OligoScan in her practice to follow heavy metals and mineral status.

Her preliminary observations intrigued her. She described one participant showing what she characterized as a small shift in mercury and aluminum after approximately three weeks of sauna use, and another long-term detoxification patient demonstrating a more pronounced change during the period in which the Relax Sauna was incorporated. Valle-Montoya was careful in the interview to describe these as early observations rather than the conclusion of a controlled clinical study. Nevertheless, they were sufficiently interesting to motivate her to pursue a more formal next phase.

This distinction is important. The clinical value of these early experiences lies less in declaring what the sauna has already “proven” than in identifying what should now be tested.

Building a Measurable Detoxification Program

Detoxification is one of the areas in which Valle-Montoya sees the greatest potential for integration. Rather than treating sauna use as an isolated wellness amenity, she envisions thermal therapy as one component within a broader protocol involving hydration, mineral support, recovery and objective monitoring.

Her future research interest is particularly ambitious: measuring environmental toxicant burden before an intervention, implementing a defined detoxification protocol incorporating far-infrared sauna, and then repeating the measurements afterward. She specifically expressed interest in studying heavy metals, PFAS and microplastics. “I want to be able to measure people’s environmental toxicities,” she explained, including “not only PFAS, not only heavy metals, but microplastics.” Her proposed model is straightforward: establish a baseline, implement the protocol and measure again. If measurable movement can be demonstrated, she believes the implications for accessible detoxification programs could be substantial.

Importantly, such a study would be needed before claims about removal of these substances could be established. Valle-Montoya’s interview therefore points toward a research hypothesis—not yet a clinical conclusion.

The “Dirty Towel” Observation

One of her most visually striking observations involved the white towels she intentionally places inside the sauna during each session. Valle-Montoya has repeatedly noticed dark or black discolorations appearing on the towels after use, across multiple patients—an occurrence she says she has not observed with the same frequency or intensity in her other sauna systems. While the source of these markings remains unknown, their recurring appearance has captured her clinical interest and raises an important question for further investigation: What exactly are these dark residues, and what might their presence reveal about the physiological processes occurring during far-infrared sauna therapy?

Scientifically, that qualification matters. Visible residue cannot simply be identified as a particular toxin without laboratory analysis. Yet the observation provides another testable question: What exactly is present in perspiration and residue collected during these sessions, and does its composition change over repeated treatments? That question could transform an anecdotal observation into a meaningful analytical investigation.

Cardiovascular Response, Recovery and Clinical Programming

Valle-Montoya also sees opportunities beyond detoxification. She reported monitoring changes in heart rate and heart-rate variability and compared the thermal response to aspects of cardiovascular exercise. In her view, the clinical story should include not only the stress induced by heat, but the body's subsequent adaptation and recovery.

“You also have to have recovery after thermoregulation in your body,” she emphasized, while underscoring hydration as an essential part of responsible sauna use.

This creates opportunities for the technology to be incorporated into broader clinical programs rather than being positioned solely as a “detox sauna.” Depending upon the patient and appropriate clinical oversight, Valle-Montoya’s model suggests studying the technology within wellness, recovery, metabolic, cardiovascular-conditioning and environmental-health programs. Its relatively short treatment window could also make it easier to pair sauna exposure with complementary assessments and therapies during a single visit.

The broader significance is programmability: sauna becomes not the program itself, but a therapeutic component within a measurable clinical pathway.

From Wellness Technology to Clinical Evidence

Valle-Montoya’s approach reflects a larger evolution occurring within integrative health. Emerging wellness technologies increasingly require more than testimonials. Practitioners need protocols, baselines, physiological endpoints, repeat measurements and reproducible observations.

That mindset is evident elsewhere in her work. In discussing other frequency-based technologies, she proposed dark-field microscopy and bioimpedance analysis as potential methods for examining before-and-after biological changes, including cellular vitality and phase angle. The same philosophy informs her interest in far-infrared sauna: observe the response, measure what can be measured, identify what remains unknown, and design the next investigation accordingly.

The Relax Sauna therefore appears to have moved, in Valle-Montoya’s assessment, from an initially unimpressive portable device to a technology worthy of deeper clinical evaluation. Its rapid heat delivery, shorter treatment window, pronounced perspiration response and potential compatibility with measurable wellness and detoxification protocols have earned her attention.

The next step is evidence. For Valle-Montoya, that means moving beyond whether a patient simply “feels better” after a sauna session. It means asking whether environmental markers change, whether physiological adaptation can be documented, whether responses differ from conventional infrared systems, and whether those findings can be reproduced across a larger population.

That is ultimately where her contribution to the HealthTech Reporter Clinical Evaluation & Performance Review becomes most valuable. She is not merely evaluating whether the Relax Far Infrared Sauna is comfortable or convenient. She is beginning to ask the more consequential clinical question:

What can this technology become when it is incorporated into a structured program, subjected to measurement, and evaluated as part of a modern evidence-building model for wellness, detoxification and progressive clinical care?

 

THE HISTORY OF SWEAT MEDICINE — PART II

 Before Science Had a Name: Ancient Observation, Ritual, and the Emerging Science of Heat

Inspired by the insights of Bobbi Kline, MD  | Edited by: Lennard M. Goetze

The historical record of sweat medicine presents a remarkable pattern of human observation. Across civilizations separated by geography, language, and culture, people repeatedly incorporated heat, sunlight, heated stones, steam, thermal water, and deliberate perspiration into practices associated with health, purification, restoration, and spiritual life. As explored in Part I, these traditions included Indigenous sweat ceremonies, Finnish sauna culture, the Mesoamerican temazcal, Greek and Roman bathing practices, natural hot springs, and the eventual medical development of heliotherapy. Although these practices differed substantially in purpose and execution, their recurrence raises an important question for contemporary investigation: whether the therapeutic significance attributed to heat historically involved considerably more than perspiration itself.

Bobbi Kline, MD, offers a useful framework for examining this possibility. Her interpretation shifts attention away from a single physiological endpoint and toward the larger environment in which ancient thermal practices occurred. Heat was rarely experienced in isolation. Depending upon the culture, thermal exposure could occur alongside water, darkness, sunlight, breathing, medicinal plants, periods of silence, communal participation, physical preparation, prayer, contemplation, and ritual. Kline emphasizes that traditions such as Native American sweat ceremonies should not be treated as a single uniform practice; nevertheless, she observes that “there are many similar elements that seem to be common across time and cultures.” This repetition does not establish medical efficacy, but it provides an important anthropological foundation for asking why comparable practices persisted independently in different societies.

One potentially important element is the physiological challenge created by heat itself. Contemporary physiology recognizes that controlled environmental stress can stimulate adaptive responses. Exercise provides the most familiar example: temporary physiological stress, when appropriately dosed and followed by recovery, can contribute to greater functional capacity and resilience. Kline identifies a conceptual similarity between this process and deliberate exposure to heat or cold. As she observes, heat and related environmental stresses “create a stress to the body that the body then has to respond” to. In appropriately controlled amounts, she argues, such stress “gets the body to adapt, to be resilient.”

This interpretation provides an intriguing bridge between ancient practice and contemporary concepts of physiological conditioning. Kline is careful to recognize limits, noting that thermal stress must remain within an appropriate window and may require gradual conditioning. Within those limits, however, she describes the process as one that may be “supporting resilience of your body's physiology.” Ancient cultures would not have described these responses through the language of cardiovascular adaptation, thermoregulation, autonomic activity, cellular stress responses, or hormesis. Their knowledge was observational rather than molecular. Nevertheless, repeated observation could establish an empirical relationship between controlled exposure, bodily response, recovery, and perceived well-being long before the mechanisms became scientifically measurable.

This distinction is important when considering the origins of medical knowledge. Institutional science is relatively recent, whereas human experimentation with the natural environment is ancient. Early societies possessed no laboratory assays, thermal imaging systems, biochemical markers, electroencephalography, or controlled clinical trials. They did, however, possess the capacity to observe reproducible phenomena. Heat caused perspiration. Intense warmth altered breathing and circulation. Cold produced a different physiological response. Sunlight influenced warmth, sleep, agriculture, behavior, and seasonal activity. Knowledge accumulated through observation, repetition, oral tradition, and cultural memory. Such practices should not be equated with modern experimental science, but neither should they be dismissed simply because their practitioners lacked contemporary terminology. The observation came first; the scientific vocabulary followed centuries later.

Reconsidering the Meaning of Prayer

Kline's interpretation of prayer provides another important perspective. Modern Western readers frequently understand prayer primarily within the framework of organized religion: prescribed language, doctrine, petition, or communication with a deity. Applying this contemporary interpretation automatically to ancient ceremonial practices, however, may obscure other functions that prayer could have served.

Kline specifically questions this assumption. “One of the things that we are potentially misinterpreting or misunderstanding is this whole sense of prayer,” she explains. Modern cultures, she notes, may associate prayer with prescribed religious practice, a script, or the act of asking an external power for intervention. She proposes another interpretation: “the idea of it actually being a form of contemplation. It's inner work. It's introspection for the goal of not only knowing more about yourself, but then self-improvement.”

This interpretation substantially changes how prayer within an ancient sweat ceremony might be considered. Rather than separating prayer from the health practice and classifying one as spiritual and the other as physiological, contemplation itself may have been an integral part of the experience. A participant undergoing intense thermal exposure is placed in an environment in which bodily sensations become difficult to ignore. Heat, perspiration, altered breathing, physical discomfort, darkness, stillness, and prolonged attention naturally direct awareness toward internal experience.

Kline connects this physical challenge directly with mental discipline. “There's the mental aspect, the discipline to be able to be uncomfortable, to sit with discomfort,” she explains. Physical discomfort, in her interpretation, inevitably directs attention inward: “Where does your mind go? Where do your thoughts go?” This relationship between physical stress and internal attention offers a potentially productive area of comparison with contemporary meditation, mindfulness, breathwork, exercise psychology, and stress-regulation practices.

What an ancient culture described through the language of prayer or spiritual preparation may therefore have included psychological processes that modern researchers would classify differently. This does not mean that ancient prayer and contemporary mindfulness are interchangeable. It suggests instead that historical terminology should be interpreted within its cultural context rather than automatically separated from questions of physiology and psychology.

The Underestimated Role of Community

The communal nature of many traditional practices introduces another important variable. Modern health interventions are increasingly individualized. Exercise may be performed alone, physiological data are collected through personal devices, and contemporary “biohacking” frequently focuses on optimization of the individual organism. Many ancient healing traditions, by contrast, were embedded within families, communities, ceremonies, and shared cultural expectations.

For Kline, this may represent one of the most overlooked differences between ancient and contemporary approaches. “We are underestimating the impact of community in healing,” she observes. She contrasts the communal structure of traditional practices with modern attempts to add increasingly sophisticated tools and biohacking technologies to individual health routines. The physiological intervention may still have effects when performed alone, she acknowledges, but she asks what changes “when you add in the spiritual component, the community component, the preparation” and “the whole ceremony around it.”

This is particularly relevant because traditional ceremonies frequently involved preparation rather than simply exposure. Kline notes that ritual may include “psychological, as well as physical and spiritual preparation.” Participants do not necessarily enter such practices casually or without conditioning; the preparation itself becomes part of the experience.

The effects of community need not be interpreted exclusively through spiritual terminology. Contemporary health science increasingly recognizes relationships among social connection, stress, behavior, adherence, psychological well-being, and health outcomes. Kline extends this discussion into more speculative territory by considering whether additional interpersonal energetic interactions may eventually become measurable. She acknowledges that these proposed phenomena remain poorly understood, stating that “we still do not fully understand” human energetic interactions and suggesting that this dimension may be “the most challenging to measure with our current science.”

That qualification is essential. These energetic interpretations should be regarded as hypotheses rather than established biomedical mechanisms. Nevertheless, Kline's larger methodological question remains relevant: when a complex historical intervention is reduced to a single measurable variable, might other meaningful components of the original experience disappear from the investigation?

From Reductionism to Synergy

Modern experimental science depends upon reductionism because isolating variables allows researchers to establish mechanisms and causal relationships. If the objective is to determine the cardiovascular effects of heat, other influences must be controlled wherever possible. Ancient practices, however, were not constructed as controlled experiments. Heat, hydration, fasting, breathing, social participation, expectation, ritual, contemplation, environmental exposure, and recovery could occur within the same experience. Consequently, studying heat alone may accurately characterize the thermal component without necessarily characterizing the complete historical practice.

Kline sees an opportunity for a broader form of scientific inquiry capable of examining both individual mechanisms and their interaction. “We are entering into a new era,” she suggests, in which research may be able to “dive deep into the molecular components, but also the energetic components.” Her larger question concerns whether science can eventually understand the “synergy” and “complex web of interaction” produced by these practices rather than reducing the entire phenomenon to a single biochemical pathway.

This does not require abandoning reductionist science. Rather, it suggests a second stage of investigation. Molecular biology can investigate cellular responses to heat. Physiology can measure circulation, thermoregulation, autonomic activity, and metabolic changes. Psychology can examine attention, expectation, stress, and resilience. Anthropology and history can preserve the cultural meaning of traditional practices, while theology and philosophy can help interpret concepts that modern biomedical terminology may inadequately represent. The challenge is ultimately to determine not only what each component does independently, but also what happens when those components are experienced together.

Before Science Had a Name

This interdisciplinary perspective may represent the most meaningful connection between ancient sweat medicine and contemporary health science. The objective should not be to prove retrospectively that ancient healers possessed knowledge equivalent to modern physiology, nor should the persistence of a practice be treated as evidence of clinical effectiveness. Rather, these traditions can be understood as repositories of accumulated human observation.

People repeatedly exposed themselves to heat, cold, sunlight, water, fasting, movement, plants, breathing practices, and altered environments because they perceived effects worthy of repeating and preserving. Some of those observations have subsequently acquired plausible physiological explanations; others remain uncertain, culturally specific, or scientifically unverified. The absence of scientific terminology does not invalidate the historical observation. It simply means that the mechanism remained unknown.

Part I of The History of Sweat Medicine established that therapeutic uses of heat, sunlight, steam, and perspiration are not modern inventions. Part II extends that history by suggesting that the intervention itself may have been more complex than heat alone. Ancient practices frequently combined physiological challenge with contemplation, preparation, community, environmental exposure, and ritual. Modern science now possesses the capacity to separate these components, measure them individually, and eventually investigate how they may interact.

Kline's most important contribution to this discussion may therefore be methodological rather than philosophical. She cautions against assuming that the measurable component is necessarily the complete component. As she observes, there may be effects within these ancient practices that are “vastly underrated or underestimated” when attention is limited to “the physiological response to the heat and the sweating.”

The historical importance of sweat medicine lies neither in romanticizing ancient practice nor in dismissing it as prescientific belief. Its importance lies in recognizing that systematic human observation preceded institutional science. Nature served as an early laboratory, while heat, light, water, plants, movement, fasting, breathing, temperature, contemplation, and community became its experimental variables. Contemporary medicine can now return to many of these observations with instruments capable of examining mechanisms that ancient practitioners could experience but could not quantify.

In this context, the history of sweat medicine becomes more than an account of humanity's early relationship with heat. It becomes part of the larger history of our attempt to understand how environment acts upon physiology, how the organism adapts to controlled stress, how mental state interacts with physical experience, and how community and ritual may alter the context in which healing occurs. Ancient practitioners could observe these interactions without possessing the means to isolate or measure them. Modern science possesses increasingly sophisticated means of measurement, but may still have something to learn from the integrated manner in which earlier cultures experienced them.

The task ahead is therefore not to ask whether ancient traditions had already discovered modern science. It is to determine which of their observations can now be investigated through modern science, which remain culturally or spiritually meaningful without requiring biomedical explanation, and which may lead to new questions that contemporary research has not yet considered.

 

About the Author

Bobbi Kline, MD, is a physician, educator, author, and integrative health strategist whose work explores the intersection of personalized medicine, genomics, women’s health, longevity, and whole-person wellness. Drawing upon decades of clinical and scientific experience, Dr. Kline examines health through a broader lens that considers physiology alongside environment, behavior, resilience, community, and the mind-body relationship. Her current work challenges conventional boundaries between established science and emerging areas of inquiry, encouraging thoughtful investigation without abandoning scientific rigor. Through writing, education, and advisory work, she advocates for a more integrated understanding of human health and our capacity for adaptation, prevention, and lifelong well-being.

THE HISTORY OF SWEAT MEDICINE

Heat, Sunlight, and the Ancient Origins of Energy-Based Healing

Excerpt from "The Science of Energy Healing" by: Lennard M. Goetze

Long before infrared saunas, photobiomodulation, thermal therapy, or the modern vocabulary of “energy medicine,” human beings were already experimenting with one of nature’s most accessible therapeutic forces: heat.

Across civilizations separated by oceans, languages, and centuries, remarkably similar practices emerged. People entered heated chambers, gathered around hot stones, bathed in steam, exposed their bodies to sunlight, immersed themselves in thermal waters, and deliberately induced perspiration. These activities were rarely viewed as simple hygiene. Heat became associated with purification, healing, restoration, spirituality, and the relationship between the human body and the natural world.

In this sense, the history of sweat medicine may represent one of humanity’s earliest attempts to use naturally occurring forms of energy therapeutically.

HEAT BEFORE MEDICINE HAD A NAME
Ancient healers did not understand infrared wavelengths, thermoregulation, vasodilation, heat-shock proteins, ultraviolet radiation, or electrolyte physiology. They learned empirically. They observed what happened when the human body encountered fire, heated stone, steam, thermal water, and sunlight. This knowledge appeared independently in multiple cultures.

Ancient Greeks and Romans developed sophisticated bathing traditions. Historical reviews of thermal medicine document that Hippocratic medicine incorporated bathing and perspiration into a broader approach to restoring bodily balance. Exercise, walking, massage, bathing, environmental changes, and sweating could all become components of health practice. Roman civilization subsequently developed elaborate public bathing complexes, including intensely heated rooms such as the caldarium.

The principle was strikingly familiar: apply heat to the body, provoke a physiological response, rest, cleanse, and recover. Yet some of the most profound traditions surrounding therapeutic heat developed far beyond Europe.

THE SWEAT LODGE: WHERE HEAT MET PRAYER
Among Indigenous peoples of the Americas, heated ceremonial structures developed as important spiritual and communal practices. It is important not to collapse these diverse traditions into a single generic “Native American sweat lodge”; ceremonies, meanings, protocols, and terminology vary substantially among nations.

Nevertheless, historical evidence clearly demonstrates that heat, perspiration, purification, prayer, and ceremony frequently intersected.

Smithsonian materials document Indigenous traditions in which sweating occurred alongside ceremonial practices, prayer, medicinal plants, purification, and even cold-water immersion. Smithsonian documentation of contemporary temazcal tradition likewise describes a sacred environment in which fire-heated stones, water, steam, medicinal plants, movement, prayer, and ceremonial songs may be brought together. The temazcal itself has pre-Columbian origins in Mexico.

This is significant because the sweat ceremony was not merely an ancient version of a modern spa.

Heat was embedded within a larger healing environment. The individual encountered darkness, warmth, steam, earth, stone, water, scent, sound, community, contemplation, and prayer simultaneously. Physical experience and spiritual experience were not necessarily separated into the categories that modern medicine uses today. The body was heated while the mind was focused and the community was gathered.

FINLAND: THE SACRED SAUNA 
Across the Atlantic, another remarkable heat tradition evolved around the Finnish sauna. The importance of sauna culture is so substantial that UNESCO inscribed Finnish sauna culture on its Representative List of the Intangible Cultural Heritage of Humanity in 2020. UNESCO describes the sauna as extending far beyond washing: traditionally it has been considered a sacred space—a kind of “church of nature”—associated with cleansing the body and mind and experiencing inner peace. Central to the traditional experience is löyly, the steam or “spirit” created when water meets heated stones.

Again, the recurring historical pattern is difficult to overlook: Heat. Water. Stone. Perspiration. Cleansing. Stillness. Nature. Spirit. Cultures separated geographically nevertheless discovered variations of the same physiological intervention.

THE SUN AS MEDICINE 
Heat medicine did not remain inside heated structures. Humanity's oldest radiant-energy source was always overhead.

The sun became associated with life and healing throughout antiquity. Greeks constructed spaces for solar exposure, and Romans developed solaria. Pliny the Elder famously expressed the ancient conviction that the sun possessed extraordinary remedial power. By the nineteenth and early twentieth centuries, these older observations began transitioning into systematic medical investigation through what became known as heliotherapy—the therapeutic application of sunlight.

The scientific story became especially important with infectious disease.

Researchers demonstrated that sunlight could damage microorganisms, and Danish physician Niels Ryberg Finsen developed concentrated light treatments for lupus vulgaris, a form of cutaneous tuberculosis. His work helped establish light as a legitimate therapeutic modality and earned him the 1903 Nobel Prize in Physiology or Medicine. Heliotherapy subsequently became incorporated into tuberculosis treatment programs before the antibiotic era.

The sun was no longer merely symbolic. Radiant energy could produce measurable biological effects.

Modern science would eventually explain additional mechanisms through which sunlight interacts with human physiology, while also establishing the very real hazards of excessive ultraviolet exposure.

WHAT ACTUALLY LEAVES THE BODY IS SWEAT?
Perhaps the most intriguing intersection between ancient belief and contemporary science concerns the concept of purification. For centuries, sweating has been interpreted culturally as a cleansing process. Modern physiology confirms one obvious function: perspiration is fundamentally a thermoregulatory system. Evaporation of sweat allows the body to dissipate heat and maintain temperature.

Sweat consists overwhelmingly of water and also contains electrolytes and numerous other substances. Researchers have detected certain environmental chemicals and toxic elements in perspiration. A systematic review examining arsenic, cadmium, lead, and mercury reported measurable excretion through sweat and found that, under some exposure conditions, concentrations could equal or exceed those found through urinary routes. The authors concluded that sweating deserved additional investigation as a potential pathway for toxic-element elimination.

But this finding should not be converted into the sweeping claim that “sweating detoxifies the body.”

A major physiological review reached a more cautious conclusion: kidneys, liver, and gastrointestinal pathways remain central to elimination, and convincing evidence that sweat glands preferentially remove environmental contaminants in clinically meaningful quantities is lacking.

Ancient people therefore may have been directionally perceptive—something does leave the body through perspiration—without possessing the analytical tools required to determine whether that elimination was therapeutically significant. That distinction creates an important opportunity for modern research.

THE FIRST ENERGY MEDICINE?
Calling ancient heat practices the direct predecessors of today's “energy medicine” requires careful terminology. They did not originate from modern concepts of electromagnetic medicine, and there is no evidence that ancient practitioners understood infrared radiation or cellular bioenergetics in contemporary scientific terms.

Yet in a broader historical sense, they were unquestionably practicing medicine through energy transfer.

Fire transferred thermal energy.

Heated stones stored and released energy.

Steam transferred heat to the body.

Sunlight delivered electromagnetic radiation.

The human organism responded through thermoregulation, circulation, perspiration, sensory signaling, neuroendocrine activity, and behavioral adaptation.

Modern sauna therapy, infrared technologies, phototherapy, thermal medicine, and photobiomodulation therefore belong to a much longer human story: the attempt to understand how externally delivered physical energy can influence biological function.

ANCIENT WISDOM MEETS MEASUREMENT 
The most compelling lesson from history is not that ancient healers had already proven modern detoxification theory. They had not. Their achievement may be more interesting than that. They observed.

Across generations, communities recognized that controlled exposure to heat produced reproducible experiences: perspiration, cardiovascular activation, relaxation, altered sensory awareness, physical cleansing, and often a powerful psychological or spiritual response. They incorporated these observations into systems of medicine, community, purification, and prayer.

Modern science can now ask questions those cultures could not. What exactly happens to circulation during controlled thermal exposure? What molecules appear in perspiration? How much is eliminated? How does heat affect inflammatory signaling, vascular function, autonomic regulation, or cellular stress responses? Which effects originate from heat itself, and which arise from rest, hydration, social connection, meditation, or ritual?

The ancient sweat lodge, Finnish sauna, Roman bath, Mexican temazcal, thermal spring, and therapeutic sun exposure should therefore not simply be dismissed as historical curiosities. They represent chapters in a much larger scientific story.

Before laboratories measured energy, human beings experienced it. Before clinicians quantified thermal physiology, cultures learned to harness heat. And before “energy medicine” became a modern term, humanity had already spent thousands of years exploring the relationship between heat, light, nature, and the healing human body.

The next chapters are not to prove that every ancient belief was correct. It is to determine—with modern measurement—which observations were.

 

ABOUT THE AUTHOR

Lennard M. Goetze is a researcher, author, publisher, and medical communications strategist whose work explores emerging health sciences, medical innovation, and advanced approaches to human wellness. He serves as Communications Director for the Male Breast Cancer Global Alliance and is the author of The Science of Energy Healing. As Publisher of Overture Publications, Goetze develops books and educational works highlighting health innovators, clinical pioneers, researchers, and leaders advancing the future of healthcare. His work focuses on translating progressive science and emerging technologies into accessible education while creating platforms that recognize the people challenging and improving conventional standards of health and medicine.

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POST REVIEW

Perhaps Sweat Is Only Part of the Story- By: Daniel Root

The significance of heat therapy may extend beyond what is physically eliminated through perspiration. Even if sweating is not a major pathway for removing heavy metals or environmental toxicants, the physiological response to heat may influence the body’s primary systems of elimination.

Heat induces vasodilation, increases circulation and cardiac output, and affects autonomic and stress responses. This raises an important research question: Could these changes support, directly or indirectly, the liver, kidneys, gastrointestinal system, and other biological pathways responsible for biotransformation and elimination?

There is also another lesson within the ancient traditions themselves. Sweat lodges, saunas, thermal bathing, and other heat practices rarely involved heat alone. They incorporated rest, hydration, breathing, ritual, social connection, spirituality, and interaction with the natural environment. Modern science tends to study these variables separately, while ancient cultures experienced them together.

Perhaps the next frontier is therefore not simply determining what leaves the body through sweat, but understanding what the entire experience of controlled heat exposure activates within the body.

Ancient cultures observed the effects. Modern science now has the opportunity to measure the mechanisms—and perhaps discover that the value of these practices lies not in one pathway, but in the synergy among many.

References

1. Sears, M. E., Kerr, K. J., & Bray, R. I. (2012). Arsenic, cadmium, lead, and mercury in sweat: A systematic review. Journal of Environmental and Public Health, 2012, 184745. DOI: 10.1155/2012/184745.
   This is one of the most useful references for your article. The systematic review examined 24 reports and found arsenic, cadmium, lead, and mercury in human sweat. The authors concluded that sweating deserves further investigation as a route for toxic-element elimination.
   PubMed record
2. Laukkanen, J. A., Laukkanen, T., & Kunutsor, S. K. (2018). Cardiovascular and other health benefits of sauna bathing: A review of the evidence. Mayo Clinic Proceedings, 93(8), 1111–1121. DOI: 10.1016/j.mayocp.2018.04.008.
   An important modern medical review connecting the ancient Finnish sauna tradition with cardiovascular, circulatory, autonomic, and other physiological effects.
   PubMed record
3. Peräsalo, J. (1988). Traditional use of the sauna for hygiene and health in Finland. Annals of Clinical Research, 20(4), 220–223. PMID: 3218891.
   Particularly valuable for the history section. It documents centuries of Finnish sauna use for cleansing, maintaining health, treating ailments, and even childbirth. It also describes the sauna as traditionally regarded as a holy place, where participants were expected to behave as they would in church.
   PubMed record
4. Heinonen, I., Laukkanen, J. A., & others. (2018). Effects of heat and cold on health, with special reference to Finnish sauna bathing. American Journal of Physiology—Regulatory, Integrative and Comparative Physiology. PMID: 29351426.
   Reviews the body's adaptation to heat and discusses mechanisms including vascular function, blood pressure, arterial stiffness, microvascular function, and cardiovascular responses.
   PubMed record
5. Matz, H., Orion, E., & Wolf, R. (2003). Balneotherapy in dermatology. Dermatologic Therapy, 16(2), 132–140.
   Useful background for the long-standing medical tradition of therapeutic bathing, mineral waters, and thermal exposure. It can help establish that therapeutic heat and water treatments preceded modern medicine by centuries.
6. Fioravanti, A., et al. / historical review: “History of the Baths and Thermal Medicine.” (2017). Clinical Cases in Mineral and Bone Metabolism.
   This historical review traces therapeutic bathing through Egyptian, Greek, Roman, and later European traditions. Particularly relevant to your article, it discusses Hippocratic recommendations involving bathing, perspiration, walking, massage, and environmental changes as part of restoring bodily balance.
   Full article in PubMed Central
7. Historical Issues of Hydrotherapy in Thermal-Mineral Springs of the Hellenic World. (2022).
   This scholarly historical review reports therapeutic use of water in ancient Greece dating to at least approximately 1000 BC, discusses the healing centers associated with Asclepius, and traces hot-water therapies through Greek, Roman, Byzantine, and Ottoman periods.
   Full article in PubMed Central
8. Carter, S. (2012). The medicalization of sunlight in the early twentieth century. Journal of Historical Sociology, 25(1), 83–105. DOI: 10.1111/j.1467-6443.2011.01405.x.
   Excellent support for the article's transition from the ancient reverence for sunlight to modern heliotherapy. It examines sunlight therapy for tuberculosis and rickets and the development of natural and artificial light as medical interventions.
   Journal article
9. Roelandts, R. (2002). The history of phototherapy: Something new under the sun? Journal of the American Academy of Dermatology, 46(6), 926–930. DOI: 10.1067/mjd.2002.121354.
   This is especially relevant to your thesis that ancient observations eventually evolved into measurable energy-based therapies. The paper describes the long history of therapeutic light and the transition to scientifically investigated ultraviolet phototherapy in the nineteenth and twentieth centuries.
10. Gøtzsche, P. C. (2011). Niels Finsen's treatment for lupus vulgaris. Journal of the Royal Society of Medicine, 104(1), 41–42. DOI: 10.1258/jrsm.2010.10k066.
    Provides historical medical documentation of Niels Ryberg Finsen's investigations into sunlight and concentrated light therapy. Finsen's work on treating lupus vulgaris with concentrated light radiation earned the 1903 Nobel Prize in Physiology or Medicine.
    Full article in PubMed Central
11. Gone, J. P., Blumstein, K. P., Dominic, D., Fox, N., Jacobs, J., Lynn, R. S., Martinez, M., & Tuomi, A. (2017). Teaching tradition: Diverse perspectives on the pilot urban American Indian traditional spirituality program. American Journal of Community Psychology. DOI: 10.1002/ajcp.12144.
    This provides scholarly support for discussing the sweat lodge as an Indigenous spiritual practice rather than reducing it to a primitive sauna. The study concerns an American Indian health center program organized around traditional spirituality and sweat lodge ceremony.
    PubMed record
12. Velásquez Luna, G., et al. (2021). Revisiting the past: Material negotiations between the Classic Maya and an entombed sweat bath at Xultun, Guatemala. Cambridge Archaeological Journal.
    This is especially valuable archaeological evidence. It describes the Mesoamerican sweat bath as a place for healing and hygiene, including historical associations with pregnancy, childbirth, postpartum care, supernatural beings, healers, and ritual practice. It provides archaeological and ethnohistoric evidence connecting heat, healing, spirituality, and ritual.
    Cambridge University Press article

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