The Unexpected Truth about Saunas and Longevity
- Rejuve.AI Team
- Aug 29
- 10 min read
Most longevity "hacks" are ironically quite short-lived. One month they're all the rage, and the next they've 'poofed'. That isn't the case with saunas.
A quick Google Trends search reveals a consistently cyclical pattern for sauna queries over the past two decades, with interest syncing almost perfectly with changes between cold and hot months in the Northern Hemisphere.
But what's more intriguing is that search interest peaks have been getting progressively higher every year, hitting their all-time high in January 2025. This record peak is likely fueled by modern science's growing investigation into the potential of sauna bathing as a therapeutic agent.
But the truth is, interest in the health benefits of saunas extends much further back than our current age of research and evidence-based medicine. It goes back thousands of years.
History of Saunas
Some forms of saunas have been present since, and possibly even before, the Bronze Age. They have played significant roles in several cultures across history, including Japanese, indigenous North American, Islamic, and, of course, Finnish culture [1].
Finland, the sauna godmother of the world, saw some of the earliest implementations of saunas, where a pit was dug into the ground with a pile of stones at the bottom. The stones were heated by a campfire, and once warm, the pit was covered with mud. Water was then poured over the hot stones to create steam [1].
For the Finnish people, saunas were (and continue to be) seen as true sanctuaries of healing.
So we have an interesting situation where contemporary scientific inquiry aligns with ancient reverence. But does all that translate into true health benefits you can experience from bathing inside a wooden chamber amidst scorching heat?
Today, we explore what the evidence truly says about saunas, your health, and whether they can actually help you live longer.
What Counts as a “Sauna”?
The term "sauna" is often used as a catch-all for any form of heat therapy, yet the specific environmental conditions of different modalities may elicit distinct physiological responses. Understanding these differences is critical, as the majority of robust longevity research has been conducted on one specific type [2].
Traditional Finnish Dry Sauna:
This is the modality at the center of most research. It is characterized by a room, typically paneled in wood, with very high air temperatures ranging from 80–100°C (176–212°F) and a low ambient relative humidity of 10–20%.
Steam Room (Turkish Bath/Hammam):
In stark contrast to the Finnish sauna, a steam room operates at much lower temperatures, typically 43–49°C (110–120°F), but with 100% relative humidity. The environment is saturated with moist heat, which prevents sweat from evaporating from the skin.
Infrared Sauna:
This modality does not primarily heat the air in the room. Instead, it uses infrared lamps to emit electromagnetic radiation that directly warms the body. The ambient air temperature is considerably lower than in a traditional sauna, usually between 49–60°C (120–140°F).
Again, non-Finnish saunas haven’t been studied as extensively. So as we start digging into the research next, we’ll be mostly focusing on Finnish saunas.
Why Would Your Body Even Benefit from a Sauna?
Think about it for a second. If you’re showering and accidentally turn the water on too hot, your body immediately reflexes for you to distance yourself from this apparent source of discomfort. So, how could we even entertain the idea that saunas are beneficial for us?
Molecular Mechanisms
Well, if you’re a good Rejuve.AI blog reader, then you remember our discussion about hormesis from our previous article on cold plunges. Hormesis is a remarkable biological phenomenon where a small dose of stress actually makes the body stronger [3].
When you step into a sauna, you’re intentionally putting yourself under a mild, controlled heat stress that is a much milder version of what your body is prepared to handle. Instead of reacting negatively, your body triggers a vast network of protective systems that not only repair cell damage but also shield you from more serious stressors down the line.
So what's happening on a deeper level? One of the key players is a family of molecules called heat shock proteins (HSPs). When your body's temperature goes up, it activates these proteins, which act like a cellular repair crew. They jump into action to fix any proteins that have become damaged or disorganized, a process that is recognized as a Hallmark of Aging [4].
Additionally, the heat from a sauna triggers a molecule that regulates the body's natural antioxidant response, helping to guard against chronic inflammation [5]. And like exercise, sauna use also temporarily boosts the body’s levels of both pro- and anti-inflammatory factors, which helps keep your immune system in balance [6].
Mechanical Effects
Beyond molecular mechanisms, saunas also have a mechanical effect on the body. When you're in the sauna, your body responds to the heat in a way that's surprisingly similar to how it responds to moderate-intensity aerobic exercise.
Your heart rate increases, sometimes as much as 150 beats per minute, and your cardiac output—the amount of blood your heart pumps per minute—can go up by 60-70%. At the same time, your blood vessels dilate and the body redistributes blood flow, sending 50-70% from your core to the skin to help you sweat and cool down [7]. Over time, this repeated training of your cardiovascular system can improve your overall heart health.
Psychosocial Influence
Finally, we can’t ignore the psychosocial side of things. As we covered earlier, sauna bathing is an ancient practice, but it's also a communal one. It's common for friends and family to go to the sauna together as a bonding activity [8].
As Associate Professor Martha Newson, who studies the effects of sauna bathing on mental wellbeing at the University of Greenwich, says:
"Sauna is a space where our norms and conventions are temporarily suspended – we take off our clothes, sit in close proximity, and endure extremes together."
This enduring connection may contribute to overall well-being and prevent psychosocial isolation—another (recently) recognized Hallmark of Aging.
The key behind these mechanisms is controlled exposure to heat, which saunas do offer. So don't intentionally go outdoors during a heatwave and expect your body to react as if it were in a sauna. In fact, that could accelerate your biological aging [9].
Do Saunas Offer Any Real Health Benefits?
Going through the mechanisms, theoretically, sauna bathing should confer benefits when it comes to actual health outcomes. Now, let's see if the data supports this notion.
Sauna Use and Neurodegenerative Disease
One of the most influential observational studies on the health outcomes correlated with regular sauna use is the Kuopio Ischemic Heart Disease (KIHD) Risk Factor Study. It tracked over 2300 middle-aged male sauna-goers in Finland. Then, over 20 years, researchers followed up with participants to check on their health and whether they developed any diseases or passed away.
And so one of the important areas covered was neurodegenerative disease. The study found that those who used a sauna 4–7 times per week had a 65% lower risk of Alzheimer’s disease and a 66% lower risk of dementia compared with once-a-week users. Researchers suggest that the combined effects of improved cardiovascular function, reduced inflammation, and better sleep may all play a role in protecting the brain [10].
Sauna Use and Mental Health
The KIHD cohort also looked into mental health. It revealed that men who used a sauna 4-7 times per week had a 77% reduced risk of developing psychotic disorders [11]. A randomized clinical trial (RCT) also supports this evidence, showing that sauna bathing was linked to a significant reduction in symptoms of major depressive disorder within one week of treatment compared to the control group [12].
Sauna Use and Immunity
Anecdotally, many sauna-goers swear they “catch fewer colds.” Clinical data seems to give them some backing. One randomized controlled trial in Germany found that people who used a sauna twice weekly for six months experienced about half as many colds as those who didn’t. Regular sessions also appear to influence immune signaling, temporarily boosting white blood cell activity and supporting the body’s defense against pathogens [13].
Sauna Use and Heart Health
Back to the KIHD study. It showed that men using saunas 2–3 times per week had about a 27% lower risk of fatal heart disease, while 4–7 weekly sessions dropped the risk by nearly half. Other research found strong associations with reduced sudden cardiac death, lower risk of hypertension, and fewer fatal cardiovascular events [14].
Sauna Use and Longevity
Finally, the big question: do saunas actually help you live longer? Evidence suggests yes, and not just by avoiding heart disease.
In the landmark 20-year KIHD study, those who used saunas 4–7 times per week had a significant 40% lower risk of dying from all causes compared with once-a-week users. Importantly, the study controlled for confounding factors like physical activity levels and socioeconomic status, strengthening the association between frequent sauna use and longevity [14].
Sauna Red Flags
While sauna bathing is well-tolerated by most healthy individuals, the significant physiological stress it induces necessitates caution for certain populations and in specific situations. So it's best to consult with your physician before you decide on trying saunas. If you end up going for it, symptoms like chest pain, severe dizziness, and palpitations are red flags that you need to exit the sauna safely.
How to Get Started with Saunas
If you’d like an evidence-based protocol for starting sauna, then the KIHD study could offer some insights. Here’s the protocol that showed the most promise in the study:
Frequency: The greatest risk reductions for mortality and dementia were seen in individuals who used the sauna 4 to 7 times per week.
Duration: Aim for sessions lasting approximately 20 minutes. The KIHD study found that sessions longer than 19 minutes were associated with significantly greater benefits than shorter sessions.
Temperature: The studies were based on traditional Finnish dry saunas, which operate at high temperatures, typically between 80∘C and 100∘C (176∘F to 212∘F), with a relatively low humidity of 10-20%.
Of course, if you’re not Finnish and aren’t well-versed in saunas, this could be a challenging protocol to follow from the get-go. But you could start slow and take it step by step, so long as you follow all safety precautions.
Conclusion
As far as longevity hacks go, saunas seem to be among the rare cases where the surging interest is met by solid scientific evidence. They show multiple health benefits across the board, including in the domains of brain health, heart health, and immunity. Not to mention, frequent sauna use has been linked to a staggering 40% decrease in death from any cause.
Breakthrough studies like the KIHD helped us generate this evidence. Collecting such data over 20 years from over 2000 individuals with such rigorous methodology is an arduous task and truly impressive feat.
But imagine if the sample size were 2 million instead. Imagine if the study had included individuals across all ages, not just middle-aged. What if the study included participants from all around the globe, not just Finland? Get this: imagine if the study actually included…women.
This is what we aspire to build with the Rejuve Longevity App. We envision it as a decentralized research platform where all sorts of longevity interventions could be tested by anybody in the world.
So if you’re a sauna enthusiast, you’ll be able to track how that affects your health. And if it works for you, then you can choose to share your protocol with others. Then if it works for them, the ripple effect continues until who knows? Maybe your own longevity protocol turns out to be the key to defeating aging.
This is not a near-future thing. We have the tools to achieve that now. All we have to find is the right signal(s). And that will come from you.
References
[1] Benke, E. (2025, May 21). Finland’s obsession with saunas is going global, but are they any good for you? Bbc.com; BBC. https://www.bbc.com/future/article/20250520-are-saunas-and-cold-plunges-good-for-your-health
[2] 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
[3] Rattan, S. I. S., & Demirovic, D. (2009). Hormesis can and Does Work in Humans. Dose-Response, 8(1), dose-response.0. https://doi.org/10.2203/dose-response.09-041.rattan
[4] Gomez, C. R. (2021). Role of heat shock proteins in aging and chronic inflammatory diseases. GeroScience. https://doi.org/10.1007/s11357-021-00394-2
[5] Ihsan, M., Deldicque, L., Molphy, J., Britto, F., Cherif, A., & Racinais, S. (2020). Skeletal Muscle Signaling Following Whole-Body and Localized Heat Exposure in Humans. Frontiers in Physiology, 11. https://doi.org/10.3389/fphys.2020.00839
[6] Hoekstra, S. P., Bishop, N. C., & Leicht, C. A. (2020). Elevating body termperature to reduce low-grade inflammation: a welcome strategy for those unable to exercise? Exercise Immunology Review, 26, 42–55. https://pubmed.ncbi.nlm.nih.gov/32139348/
[7] Gravel, H., Behzadi, P., Cardinal, S., Barry, H., Paul-Eduard Neagoe, Juneau, M., Nigam, A., Sirois, M. G., & Gagnon, D. (2020). Acute Vascular Benefits of Finnish Sauna Bathing in Patients With Stable Coronary Artery Disease. Canadian Journal of Cardiology, 37(3), 493–499. https://doi.org/10.1016/j.cjca.2020.06.017
[8] Sorri, P. (1988). The sauna and sauna bathing habits--a psychoanalytic point of view. Annals of Clinical Research, 20(4), 236–239. https://pubmed.ncbi.nlm.nih.gov/3218893/
[9] Chen, S., Liu, Y., Yi, Y., Zheng, Y., Yang, J., Li, T., Chan, T.-C., Duan, R., He, S., & Guo, C. (2025). Long-term impacts of heatwaves on accelerated ageing. Nature Climate Change. https://doi.org/10.1038/s41558-025-02407-w
[10] 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
[11] Laukkanen, T., Laukkanen, Jari A., & Kunutsor, Setor K. (2018). Sauna Bathing and Risk of Psychotic Disorders: A Prospective Cohort Study. Medical Principles and Practice, 27(6), 562–569. https://doi.org/10.1159/000493392
[12] 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., Cole, S. P., & Raison, C. L. (2016). Whole-Body Hyperthermia for the Treatment of Major Depressive Disorder. JAMA Psychiatry, 73(8), 789. https://doi.org/10.1001/jamapsychiatry.2016.1031
[13] Pilch, W., Szarek, M., Olga, C.-L., Anna, P., Żychowska, M., Ewa, S.-K., Andraščíková, Š., & Pałka, T. (2023). The effects of a single and a series of Finnish sauna sessions on the immune response and HSP-70 levels in trained and untrained men. International Journal of Hyperthermia, 40(1). https://doi.org/10.1080/02656736.2023.2179672
[14] Tanjaniina Laukkanen, 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
