The Sauna Effect: What 20 Years of Finnish Research Actually Found

Toronto has a sauna problem. Not the bad kind. Othership is selling out weekend sessions faster than a Drake drop. Go Place in Markham has 68,000 square feet of Korean-style spa and people are driving there on Tuesday nights. Backyard barrel saunas are the new hot tub. Andrew Huberman has a deliberate heat exposure protocol with seven variables. Cold plunge TikTok is a genre now.

The wellness industry runs on vibes. But Finland has been running a 20-year prospective cohort study, and the numbers are specific enough to be worth understanding.

The Finnish Study That Started the Conversation

In 2015, researchers led by Dr. Tanjaniina Laukkanen published findings in JAMA Internal Medicine that are hard to ignore. They followed 2,315 middle-aged Finnish men for an average of 20 years, tracking their sauna habits and cardiovascular outcomes. The study is called Sauna bathing and risk of sudden cardiac death, cardiovascular disease, and all-cause mortality in middle-aged men: a prospective cohort study.

Here is what they found. Men who used a sauna 4 to 7 times per week had a 63% lower risk of sudden cardiac death compared to men who used a sauna once a week. They had a 48% lower risk of fatal coronary heart disease. The association held even after adjusting for age, cardiovascular risk factors, socioeconomic status, physical activity, and alcohol consumption.

Men who took a sauna 4 to 7 times per week had a 63% lower risk of sudden cardiac death compared to those who went once a week. Laukkanen T, et al. JAMA Internal Medicine. 2015;175(4):542-548.

Those are not modest numbers. And they held across multiple statistical models. A 2018 follow-up study in BMC Medicine expanded the findings to include women and examined longer sauna sessions specifically, finding that higher frequency and longer duration were both associated with reduced fatal cardiovascular events in middle-aged to older adults.

Research suggests these are associations, not proof of direct causation. But the consistency of the findings across two decades and multiple analyses makes them worth taking seriously.

How Heat Therapy May Support Cardiovascular Health

The physiological explanation is fairly intuitive once you understand what heat does to the body. When you sit in a sauna at 80 to 100 degrees Celsius, your core temperature rises. Your blood vessels dilate to increase blood flow and help cool you down. Heart rate may increase to somewhere between 100 and 150 beats per minute, which research suggests is comparable to the load of moderate aerobic exercise.

That cardiovascular demand may support endothelial function, which is the health of the inner lining of blood vessels. Research has associated regular sauna use with reduced blood pressure, improved arterial compliance, and reduced markers of systemic inflammation. These are the same physiological variables that cardiovascular disease research consistently flags as important.

After you exit the sauna and cool down, parasympathetic nervous system activity may increase. Heart rate drops. Blood pressure falls. Evidence suggests this recovery phase may support nervous system regulation in ways that extend beyond the sauna session itself.

A 2001 review by Hannuksela and Ellahham in the American Journal of Medicine described these mechanisms in detail: vasodilation, increased cardiac output, reduced peripheral resistance, and potential improvements in endothelial function for people with coronary artery disease. These are documented physiological responses to controlled heat exposure.

What the Research Does Not Say

It does not say the sauna cures heart disease. It does not say sweating removes toxins in any clinically meaningful way. The detox framing that wellness marketing loves is not supported by the data. The cardiovascular findings are specific to the outcomes studied: mortality risk, endothelial function, blood pressure. Not vague wellness benefits.

The studies were also conducted primarily in Finnish populations with deep sauna culture and specific behavioral patterns. That does not invalidate the findings, but it is context worth holding onto.

What an Optimal Protocol Looks Like

Based on the research literature, a protocol that may support cardiovascular benefit looks like this:

• Temperature: 80 to 100 degrees Celsius (176 to 212 degrees Fahrenheit) for a traditional Finnish-style dry sauna
• Duration: 15 to 20 minutes per session. Beginners should start at 10 minutes and build gradually
• Frequency: 2 to 3 sessions per week is a reasonable starting point; the strongest associations in the Finnish data were at 4 to 7 sessions per week
• Rounds: multiple shorter rounds with cool-down periods between them is a common and well-tolerated practice
• Timing: most practitioners recommend avoiding heavy meals immediately before a session

The Othership experience is more communal and curated than a traditional Finnish sauna, but the heat exposure principles are similar. A 15-minute session at temperature is still a 15-minute session at temperature.

What to Actually Do in There

Leave your phone outside. This is not a productivity hack. It is the point. The sauna is one of the few remaining places where doing nothing is the correct behavior. Sit, lie down, sweat, and resist the urge to optimize.

• Hydrate before you go in. Water plus electrolytes. Most bad sauna experiences trace back to dehydration, not the temperature
• A sauna hat reduces the heat load on your head and is genuinely useful if you find the heat intense
• Cool down gradually after your session. A cold shower or a brief rest in cooler air allows your cardiovascular system to recover properly
• Avoid alcohol before or during sauna use. The combination impairs thermoregulation and increases cardiovascular risk
• If you have a heart condition, uncontrolled high blood pressure, or are pregnant, speak with your doctor before using a sauna

Consult a physician before starting sauna therapy if you have cardiovascular conditions, uncontrolled hypertension, or are pregnant.

What a Naturopathic Doctor Can Add

The Finnish study followed men who were already sauna users. What it could not do was assess why some people benefit more than others, or what their baseline cardiovascular health looked like.

A naturopathic doctor can investigate that baseline. Inflammation markers like high-sensitivity CRP and homocysteine. Cardiovascular risk factors that may not appear on a standard blood panel. Cortisol patterns that affect how the nervous system responds to recovery. Magnesium and electrolyte levels that influence how the body handles heat stress.

Heat therapy can be incorporated into a broader recovery and cardiovascular support protocol. But the protocol should be built around your specific clinical picture, not a generic guideline. That is what root-cause investigation means in practice.

Regular sauna use may support the cardiovascular markers that the Finnish research identified. Adding it to a naturopathic care plan, alongside appropriate lifestyle and nutritional support, may produce results that a solo sauna habit cannot.

60-minute consultations. Direct billing. No waitlist. Book at fitrahealth.ca

References

• Laukkanen T, et al. Sauna bathing and risk of sudden cardiac death, cardiovascular disease, and all-cause mortality in middle-aged men: a prospective cohort study. JAMA Intern Med. 2015;175(4):542-548.
• Laukkanen T, et al. Association between sauna bathing and fatal cardiovascular and all-cause mortality events. BMC Medicine. 2018;16(1):219.
• Hannuksela ML, Ellahham S. Benefits and risks of sauna bathing. Am J Med. 2001;110(2):118-126.

This content is for educational purposes only and does not constitute medical advice. Always consult a licensed naturopathic doctor or healthcare provider before making changes to your health routine.