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Health Benefits of Sauna Treatment (and Warnings)

The following is a summary of the cardiovascular, thermoregulatory, cellular, metabolic, immune, musculoskeletal and neurological benefits of sauna exposure, highlighting how regular heat therapy may offer an accessible and effective way to support recovery, energy and general long-term wellbeing.

Sauna Treatment for Chronic Fatigue Syndrome (CFS)

A 2015 small pilot study of 10 people with CFS reported a fall in perceived fatigue score from 6.7 to 4.8 after 4 weeks, providing significant benefit (p=0.002) (Soejima et al., 2015). Participants completed approximately 20 sessions over four weeks, consisting of a 15-minute 60°C far-infrared sauna followed by 30 minutes of rest under a blanket, performed once daily, five days per week. The study also found improvements in anxiety, depression, and overall functional performance following the intervention. (PubMed)

Mitochondrial and metabolic effects

• Possible improvement in skeletal-muscle mitochondrial respiratory capacity: Six weeks of local muscle heating increased mitochondrial respiratory capacity by approximately 25%, although it did not reproduce exercise-related improvements in fatty-acid oxidation or mitochondrial enzyme content (Marchant et al., 2022) (Moderate Level of Evidence). (MDPI)
• Increased short-term energy demand during heat exposure: Severe passive heating increases resting metabolic rate as additional energy is required for cardiac work, ventilation, sweating, ion transport and temperature regulation, although the increase is smaller than during substantial exercise (Henderson et al., 2021) (Moderate). (PubMed Central (PMC))

Possible preservation of mitochondrial function during inactivity or immobilisation: Daily local heating during ten days of leg immobilisation preserved mitochondrial function and reduced muscle atrophy by approximately 37% compared with unheated immobilisation (Hafen et al., 2019) (Moderate). (PubMed)

Cardiovascular and vascular effects

• Improved vascular dilation and endothelial stimulation: Acute sauna heating substantially increases limb blood flow and vascular shear stress, which stimulates endothelial signalling and may help preserve nitric-oxide-mediated arterial responsiveness (Leach et al., 2024) (Moderate). (Physiology Journals)
• Temporary post-sauna blood-pressure reduction: The vasodilation and reduction in arterial stiffness produced by sauna heating can temporarily reduce systolic and diastolic blood pressure during the immediate recovery period (Laukkanen et al., 2018) (Moderate). (PubMed)
• Additional cardiovascular conditioning when combined with exercise: Adding regular post-exercise sauna sessions can augment improvements in cardiorespiratory fitness, systolic blood pressure and total cholesterol beyond those achieved with exercise alone (Lee et al., 2022) (Moderate). (Physiology Journals)
• Observational associations with lower cardiovascular risk: Frequent sauna bathing has been associated with lower rates of sudden cardiac death, fatal coronary heart disease and fatal cardiovascular disease, although residual confounding prevents proof of causation (Laukkanen et al., 2015) (Moderate). (JAMA Network)

Immune and inflammatory effects

• Temporary mobilisation of leukocytes and other immune cells: A single Finnish sauna session temporarily increases circulating white blood cells, particularly neutrophils and lymphocytes, probably through redistribution from tissue and vascular storage pools rather than rapid production of new cells (Heinonen et al., 2026) (Moderate). (Taylor & Francis Online)
• Possible enhancement of short-term immune surveillance: Temporarily moving additional leukocytes into the circulation may increase their opportunity to patrol tissues and encounter pathogens, but the study did not demonstrate fewer infections or stronger clinical immunity (Heinonen et al., 2026) (Low). (Taylor & Francis Online)
• Possible reduction in chronic inflammatory markers with regular use: More frequent sauna bathing has been associated with lower long-term concentrations of high-sensitivity C-reactive protein, fibrinogen and resting leukocyte counts, although the evidence is observational (Kunutsor et al., 2018) (Moderate). (PubMed)

Musculoskeletal effects

• Relief of muscular pain and stiffness: Regular dry-sauna interventions may reduce pain and stiffness in some musculoskeletal and rheumatological conditions through warming, vasodilation and reduced muscle spasm, but the available trials are small and heterogeneous (Hussain & Cohen, 2018) (Low). (PubMed Central (PMC))
• Increased local blood flow to muscles and connective tissue: Sauna-induced vasodilation markedly increases blood flow through the limbs, potentially improving oxygen and nutrient delivery to heated muscles and surrounding tissues (Leach et al., 2024) (Moderate). (Physiology Journals)
• Possible support for muscle recovery and tissue repair: Heat exposure increases HSP expression and activates Akt-mTOR-related growth and repair signalling, but it has not yet been shown consistently to accelerate functional recovery or long-term tissue healing (Fennel et al., 2023) (Low). (Physiology Journals)

Nervous system, stress and sleep

• Possible post-sauna relaxation and parasympathetic rebound: Although sympathetic activity rises during sauna heating, the cooling period increases high-frequency heart-rate variability and shifts autonomic balance towards greater parasympathetic influence (Laukkanen et al., 2019) (Moderate). (University of Bristol)
• Possible improvement in sleep initiation and subjective sleep quality: Post-sauna relaxation, autonomic recovery and the subsequent decline in body temperature may facilitate sleep initiation, but sauna-specific sleep evidence remains predominantly subjective or observational (Laukkanen & Kunutsor, 2024) (Low). (PubMed Central (PMC))
• Reduced perception of stress and muscular tension: The combination of warmth, reduced muscle stiffness and post-heating autonomic recovery may decrease perceived stress and physical tension, although controlled evidence separating heat effects from expectation and relaxation is limited (Laukkanen & Kunutsor, 2024) (Low). (PubMed Central (PMC))

Potential long-term neurological effects

• Observational association with lower dementia and Alzheimer’s disease risk: Men reporting four to seven sauna sessions weekly had substantially lower observed rates of dementia and Alzheimer’s disease than those using a sauna once weekly, but the cohort design cannot demonstrate prevention or causation (Laukkanen et al., 2017) (Moderate). (PubMed)
• Possible contributions from improved vascular health, reduced inflammation and heat-shock protein activity: Better blood-pressure control, endothelial function, cerebral perfusion, inflammatory regulation and cellular protein protection are plausible mechanisms linking sauna use with brain health, but these pathways have not been established as mediators of reduced dementia risk (Laukkanen & Kunutsor, 2024) (Low). (PubMed Central (PMC))

Thermoregulation

• Improved heat tolerance: Repeated sauna or passive-heat exposure can expand plasma volume and reduce cardiovascular and thermal strain during later heat exposure, improving the body’s ability to tolerate hot environments (Laukkanen & Kunutsor, 2024) (Moderate). (PubMed Central (PMC))
• Earlier and more efficient sweating: Heat acclimation lowers the core-temperature threshold for sweating and increases sweat responsiveness, allowing evaporative cooling to begin earlier and regulate body temperature more effectively (Baker, 2019) (Moderate). (PubMed Central (PMC))
• Improved conservation of electrolytes during repeated heat exposure: Repeated heat exposure enhances sodium and chloride reabsorption within sweat ducts, producing more dilute sweat and reducing electrolyte loss for a given volume of perspiration (Baker, 2019) (Moderate). (PubMed Central (PMC))

Cellular stress protection

• Activation of heat-shock proteins: Whole-body heat stress increases skeletal-muscle heat-shock protein expression, strengthening cellular systems that respond to heat and protein damage (Fennel et al., 2023) (Moderate). (PubMed)
• Improved protein folding and cellular repair: Heat-induced HSPs act as molecular chaperones that can stabilise, refold or assist in removing damaged proteins, although the cited human study measured signalling rather than long-term cellular repair (Fennel et al., 2023) (Low Level of Evidence). (Physiology Journals)
• Greater cellular resistance to heat, oxidative stress and other physiological stressors: Repeated activation of heat-shock pathways may precondition cells to withstand subsequent heat and oxidative challenges, but direct evidence of lasting stress resistance in sauna users remains limited (Fennel et al., 2023) (Low). (PubMed)

Warnings and Contraindications

Always check with your GP before using a sauna. Avoid sauna use if you have severely elevated or uncontrolled blood pressure, unstable angina, a recent heart attack or stroke, severe aortic stenosis, unstable heart failure, uncontrolled arrhythmias, fever, acute illness, dehydration, significant electrolyte imbalance, impaired sweating or heat sensation, or if you are affected by alcohol or recreational drugs. Extra caution is required with pregnancy, kidney disease, fluid restrictions, orthostatic hypotension, POTS, seizure disorders, frailty, implanted cardiac devices, and medicines that affect blood pressure, hydration, sweating or temperature regulation. Stop immediately if you develop chest pain, severe headache, shortness of breath, palpitations, confusion, nausea, weakness, dizziness or faintness.

Blood Pressure Increase

A 2025 meta-analysis covering more than 400 laboratory heat studies found that sauna studies showed an average association of approximately +16 mmHg systolic per 1°C increase in core temperature. So theoretically, a 2°C rise would therefore suggest an average increase of about 32 mmHg (Meade et al., 2025).

Initial exposure guidelines

• Start at a lower temperature.
• Limit the first sessions to approximately 5-10 minutes.
• Sit near the lower bench where it is cooler.
• Hydrate beforehand and avoid entering when already dehydrated.
• Leave immediately if you feel unwell.
• Avoid rapid cold immersion after the session.

Session-duration guidelines

• Typical sessions are approximately 10-20 minutes.
• Beginners should increase exposure gradually.
• Allow time to cool down and rehydrate between repeated rounds.
• Do not remain inside simply to reach a target duration.
• Avoid prolonged sessions after strenuous exercise, alcohol use or significant fluid loss.

Common sauna temperatures

• Traditional Finnish or dry sauna: approximately 70-100°C, with 80-90°C commonly used; the Finnish Sauna Society recommends 80-100°C. (This Is FINLAND)
• Infrared sauna: approximately 43-57°C, although some units operate up to about 65°C. (Cleveland Clinic)
• Steam room: approximately 40-50°C, but the near-100% humidity makes it feel considerably hotter than a dry sauna at the same temperature.
• Lower-temperature beginner range: approximately 60-70°C in a traditional sauna, with shorter exposure initially.

Humidity, airflow, bench height and whether water is poured onto the stones can substantially change how hot a sauna feels even when the thermometer reading remains the same.

The air immediately next to exposed skin is generally close to the surrounding sauna-air temperature, but it is not fixed at exactly the thermometer reading because the skin creates a thin, cooler and more humid boundary layer.

In a traditional sauna set to 80–100°C:

• Air a few centimetres from the skin at upper-bench or torso height may still be roughly 70–100°C, depending on bench height, airflow and distance from the heater.
• The microscopic layer directly touching the skin is cooler because heat is absorbed by the body and sweat evaporates, but it is difficult to assign one temperature to it.
• The skin itself usually rises only to about 40–41°C, not 80–100°C. (PubMed)
• Air around the lower legs and feet can be substantially cooler because sauna air is strongly stratified vertically.
• Pouring water on the stones may not greatly raise the measured air temperature, but the additional humidity reduces sweat evaporation and sharply increases heat transfer to the skin.

Therefore, an 80–100°C sauna really does expose the skin to air near that temperature, particularly around the head and upper torso, while evaporative cooling and blood circulation keep the actual skin temperature near approximately 40°C.

Passive Sauna Suits

Passive sauna suits trap heat and raise body temperature during exercise. Research has found that after 30 minutes of cycling in an upper-body vinyl passive sauna suit:

• At 22°C and 45% humidity, peak mean skin temperature was 33.41 ± 0.70°C in the sauna suit, compared with 33.06 ± 0.97°C without it.
• At 45°C and 20% humidity, peak mean skin temperature reached 37.68 ± 0.68°C in the sauna suit, compared with 36.53 ± 0.93°C without it.
• Individual mean skin temperatures in the hot-condition sauna-suit trial appeared to range from approximately 36–39°C;
• Importantly, the suit increased core-temperature rise and sweat loss even when mean skin temperature at 22°C barely changed. This means skin temperature alone can underestimate the physiological heat strain produced by a sauna suit.

Active Sauna Tents and Sauna Pods vs Traditional Sauna

Traditional saunas can raise the core body temperature 1.78C after 30 minutes. This would correspond roughly to a rise such as: 36.7°C → 38.5°C

Research shows that Sauna Tents and Sauna Pods are able to raise average core body temperature to 38.10C, though it can take longer to do so.

The heating protocol was:

- 20 minutes inside the pod

- 5 minutes outside

- another 20 minutes inside

- another 5 minutes outside

- a final 20 minutes inside

Devices tested had the following specifications:

• 900-1300 watt 3L steamer.
• an external electric water steamer;
• plastic tubing carrying steam into the enclosure;
• multiple heat settings;
• a PVC supporting frame;
• multilayer cotton insulation and polyester waterproofing;
• an internal volume of approximately 0.6 m³;
• dimensions of approximately 72 cm wide × 99 cm deep × 85 cm high;
• a neck opening that left the participant's head outside;
• a folding chair inside the enclosure.

At maximum setting, the pod maintained approximately 44°C and 99% relative humidity. Humidity remained near 99% for approximately 51 minutes of the protocol.

References

Baker, L. B. (2019). Physiology of sweat gland function: The roles of sweating and sweat composition in human health. Temperature, 6(3), 211-259. https://doi.org/10.1080/23328940.2019.1632145

Fennel, Z. J., Ducharme, J. B., Berkemeier, Q. N., Specht, J. W., McKenna, Z. J., Simpson, S. E., Nava, R. C., Escobar, K. A., Hafen, P. S., Deyhle, M. R., Amorim, F. T., & Mermier, C. M. (2023). Effect of heat stress on heat shock protein expression and hypertrophy-related signaling in the skeletal muscle of trained individuals. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 325(6), R735-R749. https://doi.org/10.1152/ajpregu.00031.2023

Hafen, P. S., Abbott, K., Bowden, J., Lopiano, R., Hancock, C. R., & Hyldahl, R. D. (2019). Daily heat treatment maintains mitochondrial function and attenuates atrophy in human skeletal muscle subjected to immobilization. Journal of Applied Physiology, 127(1), 47-57. https://doi.org/10.1152/japplphysiol.01098.2018

Heinonen, I. H. A., Koivula, T., Hollmén, M., Immonen, J., Kunutsor, S. K., Jalkanen, S., & Laukkanen, J. A. (2026). Acute Finnish sauna heat exposure induces stronger immune cell than cytokine responses. Temperature, 13(2), 186-199. https://doi.org/10.1080/23328940.2026.2645467

Henderson, M. E. T., Brayson, D., & Halsey, L. G. (2021). The cardio-respiratory effects of passive heating and the human thermoneutral zone. Physiological Reports, 9(16), e14973. https://doi.org/10.14814/phy2.14973

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

Kunutsor, S. K., Laukkanen, T., & Laukkanen, J. A. (2018). Longitudinal associations of sauna bathing with inflammation and oxidative stress: The KIHD prospective cohort study. Annals of Medicine, 50(5), 437-442. https://doi.org/10.1080/07853890.2018.1489143

Laukkanen, J. A., & Kunutsor, S. K. (2024). The multifaceted benefits of passive heat therapies for extending the healthspan: A comprehensive review with a focus on Finnish sauna. Temperature, 11(1), 27-51. https://doi.org/10.1080/23328940.2023.2300623

Laukkanen, T., Khan, H., Zaccardi, F., & Laukkanen, J. A. (2015). Association between sauna bathing and fatal cardiovascular and all-cause mortality events. JAMA Internal Medicine, 175(4), 542-548. https://doi.org/10.1001/jamainternmed.2014.8187

Laukkanen, T., Kunutsor, S. K., Kauhanen, J., & Laukkanen, J. A. (2017). Sauna bathing is inversely associated with dementia and Alzheimer’s disease in middle-aged Finnish men. Age and Ageing, 46(2), 245-249. https://doi.org/10.1093/ageing/afw212

Laukkanen, T., Kunutsor, S. K., Zaccardi, F., Lee, E., Willeit, P., Khan, H., & Laukkanen, J. A. (2018). Acute effects of sauna bathing on cardiovascular function. Journal of Human Hypertension, 32(2), 129-138. https://doi.org/10.1038/s41371-017-0008-z

Laukkanen, T., Lipponen, J., Kunutsor, S. K., Zaccardi, F., Araújo, C. G. S., Mäkikallio, T. H., Khan, H., Willeit, P., Lee, E., Poikonen, S., Tarvainen, M. P., & Laukkanen, J. A. (2019). Recovery from sauna bathing favorably modulates cardiac autonomic nervous system. Complementary Therapies in Medicine, 45, 190-197. https://doi.org/10.1016/j.ctim.2019.06.011

Leach, O. K., Strong, K., Mack, G. W., & Gifford, J. R. (2024). The vascular response to acute sauna heating is similar in young and middle-aged adults. Journal of Applied Physiology, 136(3), 573-582. https://doi.org/10.1152/japplphysiol.00287.2023

Lee, E., Kolunsarka, I., Kostensalo, J., Ahtiainen, J. P., Haapala, E. A., Willeit, P., Kunutsor, S. K., & Laukkanen, J. A. (2022). Effects of regular sauna bathing in conjunction with exercise on cardiovascular function: A multi-arm, randomized controlled trial. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 323(3), R289-R299. https://doi.org/10.1152/ajpregu.00076.2022

Marchant, E. D., Kaluhiokalani, J. P., Wallace, T. E., Ahmadi, M., Dorff, A., Linde, J. J., Leach, O. K., Hyldahl, R. D., Gifford, J. R., & Hancock, C. R. (2022). Localized heat therapy improves mitochondrial respiratory capacity but not fatty acid oxidation. International Journal of Molecular Sciences, 23(15), 8500. https://doi.org/10.3390/ijms23158500

Meade, R. D., Akerman, A. P., Notley, S. R., McGarr, G. W., McCourt, E. R., Kirby, N. V., Costello, J. T., Cotter, J. D., Crandall, C. G., Zanobetti, A., & Kenny, G. P. (2025). Meta-analysis of heat-induced changes in cardiac function from over 400 laboratory-based heat exposure studies. Nature Communications, 16, Article 2543. https://doi.org/10.1038/s41467-025-57868-6

Soejima, Y., Munemoto, T., Masuda, A., Uwatoko, Y., Miyata, M., & Tei, C. (2015). Effects of Waon therapy on chronic fatigue syndrome: A pilot study. Internal Medicine, 54(3), 333–338. https://doi.org/10.2169/internalmedicine.54.3042

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