Traditional Saunas: What the Science Actually Says

If you hang around the wellness world long enough, you’ll hear a lot of bold claims about sauna bathing: detox, longevity, heart health, brain health, better sleep…the list gets long fast.

The good news? When we’re talking about traditional Finnish-style saunas—dry heat, hot rocks, optional steam—there’s actually a surprising amount of real data behind those claims.

Below is a rundown of what the medical literature shows so far, and where the evidence is still developing.

First, What Do Researchers Mean by “Traditional Sauna”?

Almost all of the big, long-term studies come from Finland and use a consistent setup:

• Temperature: ~70–100°C (158–212°F)

• Humidity: relatively low (10–20%), with brief steam bursts when water is thrown on the rocks

• Duration: typically 10–20 minutes per session

• Frequency: anywhere from 1 to 7 sessions per week

So when you see headlines about “sauna use reducing mortality” or “sauna and dementia risk,” they’re almost always talking about dry, traditional Finnish saunas, not infrared. PMC+1

Cardiovascular Health & Mortality

One of the most cited pieces of research is a prospective cohort study from the Kuopio Ischaemic Heart Disease (KIHD) study in Finland, published in JAMA Internal Medicine in 2015. It followed more than 2,300 middle-aged men for about 20 years and looked at how often they used the sauna. PubMed+1

Compared with men who used a sauna once per week, those who went:

• 2–3 times per week had significantly lower risk of:

  • sudden cardiac death

  • fatal coronary heart disease

  • fatal cardiovascular disease

  • all-cause mortality

• 4–7 times per week had even larger risk reductions:

  • roughly 40% lower all-cause mortality

  • about 50–60% lower fatal cardiovascular mortality, including sudden cardiac death, in some analyses JAMA Network+1

Later work that included both men and women showed similar associations: more frequent traditional sauna bathing was linked to reduced cardiovascular mortality and improved risk prediction beyond standard risk factors. PubMed+1

Important nuance: these are observational studies. They can’t prove that sauna use causes lower mortality, but the associations remain statistically strong even after adjusting for age, smoking, physical activity, and other common risk factors.

How Could Sitting in a Hot Room Help Your Heart?

Mechanistically, a traditional sauna session looks a lot like a mild cardiovascular workout:

• Heart rate can climb into the 100–150 beats per minute range

• Blood vessels dilate (vasodilation), improving blood flow

• Core body temperature rises by ~1–2°C

• The autonomic nervous system shifts toward relaxation post-session

A 2018 review in Mayo Clinic Proceedings suggested that repeated heat exposure may support cardiovascular health by: Mayo Clinic Proceedings+1

• lowering blood pressure

• improving endothelial function (how well blood vessels dilate)

• reducing arterial stiffness

• decreasing inflammation and oxidative stress

• improving autonomic balance (more parasympathetic “rest and digest”)

In other words, traditional sauna sessions behave a bit like a passive “cardio” stimulus plus a stress-management tool at the same time.

Blood Pressure & Vascular Function

Several clinical and experimental studies have looked specifically at blood pressure and vascular health:

• A systematic review of dry sauna interventions found modest but meaningful average reductions in both systolic and diastolic blood pressure, on the order of ~4 mmHg in some heat-therapy protocols. PMC+1

• More recent work in people with coronary artery disease suggests that 8 weeks of regular Finnish sauna use can improve markers of vascular function (for example, flow-mediated dilation, a measure of how well arteries relax). Physiology Journals+1

• In patients with untreated hypertension, combining exercise with sauna sessions has shown beneficial effects on 24-hour blood pressure readings, compared to exercise alone. PMC+1

These numbers might not sound huge, but a 4–5 mmHg drop in systolic blood pressure at the population level is considered a big win for cardiovascular risk.

Brain Health, Dementia & Alzheimer’s Disease

The brain data is one of the most interesting—and still evolving—areas.

In 2017, an analysis from the KIHD study looked at traditional sauna use and risk of dementia and Alzheimer’s disease in more than 2,000 men followed for about 20 years. Men who used a Finnish sauna 4–7 times per week had: OUP Academic+1

• 66% lower risk of developing dementia

• 65% lower risk of developing Alzheimer’s disease

compared with those who used the sauna once per week.

Again, this is observational—it doesn’t prove causation—but the magnitude of the association is hard to ignore.

Mechanistically, researchers are exploring a few ideas:

• Improved vascular health → better blood flow to the brain

• Reduced blood pressure and arterial stiffness

• Heat shock proteins (HSPs) that may support protein folding and cellular resilience

• Anti-inflammatory effects and improved metabolic health

Preclinical work has even shown that “sauna-like” mild hyperthermia in animal models can reduce tau phosphorylation, one of the pathological features of Alzheimer’s disease, although that’s still early-stage science. ScienceDirect+1

Mental Health, Mood & Stress

Traditional sauna bathing doesn’t just impact the heart and blood vessels; there’s emerging evidence it may influence mood and mental health:

• A 2024 review of passive heat therapies (including Finnish sauna) highlighted associations between frequent sauna use and better health-related quality of life, lower risk of psychosis, and improvements in markers linked to stress and mood. PMC

• Some smaller trials and case series have suggested potential benefits for conditions like depression or chronic pain, potentially via endorphin release, autonomic balance, and reduced inflammation, though this area still needs larger, controlled trials. PMC+1

Subjectively, most people don’t need a paper to tell them they feel calmer after 15–20 minutes in a traditional sauna. The science is slowly catching up to that experience.

Exercise, Fitness & Metabolic Effects

Traditional sauna bathing also appears to complement exercise:

• In a recent trial, adding sauna sessions after exercise improved cardiorespiratory fitness, lowered systolic blood pressure, and reduced total cholesterol more than exercise alone. PubMed+1

• Heat exposure acts as a hormetic stressor: the body briefly experiences a challenge (heat), which triggers adaptations like increased plasma volume, improved heat tolerance, and potential improvements in insulin sensitivity and endothelial function. Mayo Clinic Proceedings+1

Think of it as an extra “nudge” to your cardiovascular and metabolic systems—without having to add more high-intensity training.

How Often Is “Enough”?

Most of the impressive associations in the Finnish data show up in people using a traditional sauna:

• 2–3 times per week for meaningful benefits

• 4–7 times per week for the largest reductions in cardiovascular and dementia risk JAMA Network+1

Typical session lengths were 10–20 minutes, often with two or three rounds separated by brief cool-downs.

The key isn’t intensity or suffering; it’s consistent, repeat exposure over months and years.

Safety & Who Should Be Cautious

For most generally healthy people, traditional saunas are considered safe when used sensibly. That said, there are some important caveats:

• People with unstable cardiovascular disease, recent heart attack, or severe aortic stenosis should talk to their physician before using a sauna.

• Anyone prone to low blood pressure, fainting, or dehydration needs to be especially careful with duration and hydration.

• Alcohol plus sauna is a bad combination and has been linked with adverse events. Mayo Clinic Proceedings+1

As with exercise, if you have significant medical conditions, it’s worth getting a personalized green light from a healthcare professional.

The Bottom Line

If you strip away the hype and just look at the data, traditional Finnish-style saunas are one of the more evidence-backed “wellness” practices we have:

• Strong observational links to lower cardiovascular and all-cause mortality

• Associations with reduced risk of dementia and Alzheimer’s disease

• Improvements in blood pressure, vascular function, and cardiorespiratory fitness in intervention studies

• Emerging evidence for benefits in mental health, chronic pain, and quality of life

We still need more randomized, controlled trials to nail down mechanisms and ideal “doses,” but the overall picture is remarkably consistent: regular traditional sauna use looks like a powerful, low-tech way to support cardiovascular, brain, and overall health.