My first exposure to sauna bathing in Alaska occurred at a fish camp in Kenai the summer of 1995. I was one of roughly 30 slime-liners camping in the yard next to a fishery waiting for the salmon run to appear so the work could begin. It was a cold, rainy summer and we had plenty of time on our hands. We borrowed some shovels from the cannery and started digging. Soon enough we had a large pit in the ground covered with tarps and a make-shift chimney made from a piece of pipe we found. We even had a little changing tent set up outside the entrance. We built fires under a pile of rocks and heated them until they were glowing red. Then we would take turns sitting and sweating in small groups, periodically splashing water on the rocks to create steam. We started out as strangers in a soggy fish camp, but building and enduring the sweltering heat of a sauna together bonded us and warmed our souls.

Saunas have a rich history in Alaska. They also have abundant health benefits and are becoming increasingly popular worldwide. Saunas have been associated with health and spiritual benefits in ancient populations for thousands of years, however recent publication of scientific studies have confirmed benefits such as decreased overall mortality, improved cardiovascular and neurovascular health, and reduced incidence of sudden death from cardiac events.[8,9]

History of Saunas in Alaska

Alaskans began sauna bathing thousands of years ago; long before Western contact. Yupik people built qasqigs, which were small holes dug into the tundra with room for one or two people.[1] A fire was built in the pit until it was heated to nearly 250˚F. They wore loon skin caps to protect their ears and eyes and held woven respirators filled with wood chips in their mouths to protect their lungs.[1] One’s ability to tolerate the intense heat of the “fire bath” was a sign of strength. The qasqigs were used in spiritual practice to purify themselves, bathe, and heal both psychological and physical ailments, and similar versions of the fire bath existed in other indigenous groups throughout the state.

The arrival of Russian fur traders brought banyas, which were larger, above-ground structures that accommodated more communal sauna bathing and are still used throughout Alaska today. Traditionally, the men go first, then women and children follow in more tolerable temperatures.

Physiology of Sauna Bathing

While humans have been sauna bathing world-wide for centuries, the Finnish people have perfected the art of the sauna, and it is deeply woven into the fabric of their culture. There are 5 million people residing in Finland and 3 million saunas! Sauna bathing appears to improve cardiovascular, neurovascular, and inflammatory health. In fact, a long-term, comprehensive study published in 2015 followed 2,315 Finnish men over 20 years and found that increased sauna use (4 to 7 times weekly) decreased both all-cause mortality and sudden cardiovascular death by a staggering 40% and 48% respectively compared to 1 time per week use.[8] That’s a pretty impressive statistic. Let’s take a look at some of the evidence.

Heat Shock Proteins

There are several physiological processes that occur in response to heat stress that are greatly beneficial for the body in a controlled environment. One such process is the upregulation of heat shock proteins (HSPs). HSPs work to repair proteins that have been damaged by oxidative and immunological processes that result from normal cellular metabolism. Ordinarily, cells maintain a low level of HSPs that help stabilize protein function and repair the damaged proteins. But heat stress specifically has been shown to dramatically increase the amount of circulating HSPs by up to 49%, which is sustained over time, thereby providing long term protective effects.[2] Increased numbers of damaged and disordered proteins are a common finding in chronic cardiovascular diseases, as well as neurodegenerative diseases such as Alzheimer’s and Parkinson’s.[11] Thus, more circulating HSPs could work to prevent the development or progression of these chronic diseases.

Cardiovascular Health

Sauna bathing can be likened to performing a cardio workout without even moving a muscle. The heart rate and blood pressure increase, just as they would during moderate exercise, and returns to pre-sauna levels after completion. This, in conjunction with the molecular processes elicited in response to heat, provides the entire cardiovascular system with the benefits of a moderate exercise workout that can have long lasting and positive effects if done regularly.

Congestive heart failure (CHF) occurs when the heart is too weak or too stiff to adequately pump blood. It results in reduced blood flow to both the heart and peripheral tissues, which leads to fluid accumulation, shortness of air, and an increase in the size of the left ventricle. Sauna bathing has been shown to improve CHF patients’ endurance, heart size, and disease status after 2 weeks of therapy compared to those who received medical care only.[11, 4, 14] Additionally, coronary artery disease (CAD), characterized by reduced blood flow to the heart, is the leading cause of sudden cardiac death in the western hemisphere. A randomized controlled trial demonstrated that 15 sauna sessions given over a period of 3 weeks resulted in improved blood flow to the heart compared to those who did not sauna.[13]

Sauna bathing has also been shown to improve blood pressure, endothelial dysfunction, and cholesterol levels. Chronic hypertension, CHF, CAD, and peripheral artery disease are the result of a lack of arterial elasticity or compliance. Arteries have an endothelial lining that secretes both vasoconstrictors and vasodilators, chemicals that help control the blood pressure and the movement of oxygenated blood around the body. Patients with endothelial dysfunction release too much vasoconstrictor and too little vasodilator chemicals, rendering their arterial system stiff and non-compliant. However, sauna bathing even just once a week has been shown to lower blood pressure and improve arterial compliance.[10] Additionally, two weeks of consistent sauna therapy resulted in significant improvement in endothelial and cardiac function in patients with CHF.[5] And one study in which participants exposed to 50 sauna sessions over a 10 week period resulted in improved lower extremity circulation, walking endurance, and pain in patients with advanced peripheral artery disease.[15]

High cholesterol levels may contribute to the development of cardiovascular disease and pose an increased risk for stroke to occur. Sauna use appears to contribute to lower blood lipid levels, or cholesterol. In a small study in which women were exposed to seven 30-minute saunas over a period of two weeks, both total cholesterol and LDL were significantly lowered compared to those who did not sauna.[12]

Cardiovascular disease greatly contributes to cognitive decline in response to overall reduced blood flow to the brain. Regular sauna use appears to reduce cognitive decline by increasing brain blood flow, in addition to a cascade of other molecular processes that elicit protective neuronal effects.[11]

Brain Protection

Brain-derived neurotrophic factor (BDNF) is an important growth factor that is produced in the brain and acts on the central nervous system. It promotes the growth of new neurons, modulates the formation of neuronal networks, and helps to ameliorate anxiety and depression from life stressors. Regular sauna bathing may promote the growth of new neurons and increase clearance of beta amyloid proteins through an upregulation of BDNF and increased brain circulation.[6] This potentially lends itself to increased concentration and focus, decreased anxiety and depression, and a reduced rate of development of neurodegenerative diseases.[11] Remarkably, in a study of approximately 2000 Finnish men, those who utilized the sauna 4 to 7 times per week had a 65% decreased risk of developing Alzheimer’s disease compared to those who bathed 1 time per week.[9]

Sauna use has also been shown to increase the production of norepinephrine, a neurotransmitter, and prolactin, a hormone produced in the pituitary gland. Norepinephrine is known to enhance focus and attention, and prolactin increases the production of myelin, which aids in faster neuronal signaling and is a critical feature of nerve cell repair.[11] Studies of both men and women who sauna bathed for 20 minutes just twice a week demonstrated a marked increase in both norepinephrine (86%) and prolactin (510%) at the end of each session.[7]

Decreased Inflammation

Inflammation plays an important role in the immunological response to disease and injury. However, chronic inflammation is a damaging condition which underlies multiple chronic diseases, including CHF, depression, cancer, and diabetes. It does so by reducing our bodies’ ability to repair cells and proteins that are damaged from everyday exposure to toxins and stress. C-Reactive protein (CRP) is involved in the acute inflammatory cascade of chemicals in the immunological response. However, chronically elevated CRP is associated with the development of atherosclerosis and cardiac disease.[11] Regular sauna use demonstrated reduced levels of CRP in a study of 2000 men in Finland.[8] In fact, the more often the sauna bathing occurred, the lower the detectable CRP level.

Regular sauna use also appears to increase levels of interleukin-10, an anti-inflammatory chemical that naturally occurs in balance with other chemical messengers to modulate the inflammatory response.[11] In a small study including both athletes and non-athletes, the serum levels of IL-10 significantly increased after two 15-minute sauna sessions separated by a cold plunge bath.[16]

Benefit to Those with High Stress Occupations

First responders, military personnel, police officers, medical providers, and others with high stress occupations (HSOs) may benefit from regular sauna use. HSOs have been associated with increased levels of cortisol and pro-inflammatory pathways, which can lead to the development of several cardiometabolic diseases, such as atherosclerosis, obesity, heart disease, and sudden cardiac death.[3] Additionally, first responders are potentially exposed to extreme heat, smoke, and multiple oxidative toxins. Oftentimes, people who work in HSOs find it hard to adhere to diet and exercise prescriptions due to shift work, long hours, disturbed sleep cycles, poor nutrition, and lack of a routine that would

lend to the development of healthy habits. Regular sauna use may be a practical and beneficial adjunct to medical interventions used by these individuals to combat the deleterious effects of their high stress occupations.[3]

Frequency, Duration, and Temperature Recommendations

As previously stated, greater frequency of sauna sessions per week results in greater health benefits. But even one to two sessions per week could provide some benefit, which in combination with proper diet and exercise habits could extend your lifespan. To reap the most benefits of dry sauna bathing, sessions should occur 4 to 7 times per week and last 20 to 30 minutes at a time, with a temperature range of 170˚ to 200˚F.[8] This can be accomplished via indoor electric heaters or outdoor wood fired heat. Many people practice by sitting 10 to 20 minutes at a time and then cooling off in between sessions. Pouring water on hot rocks to create a little steam is also common practice.

Sauna bathing is perfectly safe for healthy people but may not be appropriate for all. Those who have suffered a recent heart attack should not sauna. And those who have any diagnosed cardiac condition should consult their physician prior to partaking in sauna bathing. Men with fertility issues and pregnant women should also consult with their physician. Additionally, sauna bathing is contraindicated for those with acute febrile illness and those taking specific medications. In general, it is a good idea to run it by a physician if one has any health conditions at all.

In conclusion, the heat stress from sauna use initiates a multitude of molecular processes that provide protective effects to the body, similar to a moderate intensity workout, that may lead to a longer, higher quality of life. This is not to say we shouldn’t exercise; we still need that to keep bones and muscles healthy. However, it is an ancient practice that is generally safe for healthy populations and those with certain health conditions under medical supervision. And it may be a helpful adjunct to those with high stress occupations to combat the deleterious health effects of their career.

Disclaimer: The information provided in this blog is intended for informational purposes only and should not be construed as medical advice. Saunas can have various health benefits, but individual results may vary. It is important to consult with your healthcare provider before using saunas, especially if you have any pre-existing medical conditions or concerns. Your healthcare provider can provide personalized guidance based on your medical history and help determine if saunas are a safe option for you. Always prioritize your health and well-being by seeking professional medical advice before making any lifestyle changes or starting new wellness routines

References

1. Englehard, M. (2021). Alaska Steambath Culture. Alaska Magazine January 26, 2021 https://alaskamagazine.com/authentic-alaska/culture/alaska-steambath-culture/
2. Hafen, P. S., Preece, C. N., Sorensen, J. R., Hancock, C. R., & Hyldahl, R. D. (2018). Repeated exposure to heat stress induces mitochondrial adaptation in human skeletal muscle. Journal of applied physiology, 125(5), 1447–1455. https://doi.org/10.1152/japplphysiol.00383.2018
3. Henderson, K. N., Killen, L. G., O'Neal, E. K., & Waldman, H. S. (2021). The Cardiometabolic Health Benefits of Sauna Exposure in Individuals with High-Stress Occupations. A Mechanistic Review. International journal of environmental research and public health, 18(3), 1105. https://doi.org/10.3390/ijerph18031105
4. Hussain, J., & Cohen, M. (2018). Clinical Effects of Regular Dry Sauna Bathing: A Systematic Review. Evidence-based complementary and alternative medicine: eCAM, 2018, 1857413. https://doi.org/10.1155/2018/1857413
5. Kihara, T., Biro, S., Imamura, M., Yoshifuku, S., Takasaki, K., Ikeda, Y., Otuji, Y., Minagoe, S., Toyama, Y., & Tei, C. (2002). Repeated sauna treatment improves vascular endothelial and cardiac function in patients with chronic heart failure. Journal of the American College of Cardiology, 39(5), 754–759. https://doi.org/10.1016/s0735-1097(01)01824-1
6. Kojima, D., Nakamura, T., Banno, M., Umemoto, Y., Kinoshita, T., Ishida, Y., & Tajima, F. (2018). Head-out immersion in hot water increases serum BDNF in healthy males. International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group, 34(6), 834–839. https://doi.org/10.1080/02656736.2017.1394502
7. Laatikainen, T., Salminen, K., Kohvakka, A., & Pettersson, J. (1988). Response of plasma endorphins, prolactin and catecholamines in women to intense heat in a sauna. European journal of applied physiology and occupational physiology, 57(1), 98–102. https://doi.org/10.1007/BF00691246
8. 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
9. Laukkanen, T., Kunutsor, S., 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
10. Lee, E., Laukkanen, T., Kunutsor, S. K., Khan, H., Willeit, P., Zaccardi, F., & Laukkanen, J. A. (2018). Sauna exposure leads to improved arterial compliance: Findings from a non-randomised experimental study. European journal of preventive cardiology, 25(2), 130–138. https://doi.org/10.1177/2047487317737629
11. Patrick, R. (2023). Foundmyfitness topic - sauna. FoundMyFitness. https://www.foundmyfitness.com/topics/sauna
12. Pilch, W., Szyguła, Z., Klimek, A. T., Pałka, T., Cisoń, T., Pilch, P., & Torii, M. (2010). Changes in the lipid profile of blood serum in women taking sauna baths of various duration. International journal of occupational medicine and environmental health, 23(2), 167–174. https://doi.org/10.2478/v10001-010-0020-9
13. Sobajima, M., Nozawa, T., Ihori, H., Shida, T., Ohori, T., Suzuki, T., Matsuki, A., Yasumura, S., & Inoue, H. (2013). Repeated sauna therapy improves myocardial perfusion in patients with chronically occluded coronary artery-related ischemia. International journal of cardiology, 167(1), 237–243. https://doi.org/10.1016/j.ijcard.2011.12.064
14. Tei, C., Shinsato, T., Miyata, M., Kihara, T., & Hamasaki, S. (2007). Waon therapy improves peripheral arterial disease. Journal of the American College of Cardiology, 50(22), 2169–2171. https://doi.org/10.1016/j.jacc.2007.08.025
15. Tei, C., Imamura, T., Kinugawa, K., Inoue, T., Masuyama, T., Inoue, H., Noike, H., Muramatsu, T., Takeishi, Y., Saku, K., Harada, K., Daida, H., Kobayashi, Y., Hagiwara, N., Nagayama, M., Momomura, S., Yonezawa, K., Ito, H., Gojo, S., Akaishi, M., … WAON-CHF Study Investigators (2016). Waon Therapy for Managing Chronic Heart Failure - Results From a Multicenter Prospective Randomized WAON-CHF Study. Circulation journal : official journal of the Japanese Circulation Society, 80(4), 827–834. https://doi.org/10.1253/circj.CJ-16-0051
16. Żychowska, M., Nowak-Zaleska, A., Chruściński, G., Zaleski, R., Mieszkowski, J., Niespodziński, B., Tymański, R., & Kochanowicz, A. (2018). Association of High Cardiovascular Fitness and the Rate of Adaptation to Heat Stress. BioMed research international, 2018, 1685368. https://doi.org/10.1155/2018/1685368