The sauna is one of the most studied health habits in the world. Researchers have published roughly 400 to 500 papers on what heat does to the body, and over the last decade large clinical studies have moved the conversation from folklore to data.
Most of that research comes out of Finland, where the traditional sauna has been part of daily life for centuries. The Finnish Sauna Society has documented these effects for years. This page takes that work, adds the modern clinical evidence published in journals like JAMA Internal Medicine and Mayo Clinic Proceedings, and lays it out in plain terms for an American audience.
A note on scope. The studies below were conducted on traditional, high heat saunas, the kind that use a stove and hot stones with water poured over them. That is the style BW Sauna Co. builds, and it is the style the research measured.
Key Takeaways
- A 20 year Finnish study of 2,315 men found that frequent sauna use was associated with a 50 percent lower risk of fatal cardiovascular disease and a 63 percent lower risk of sudden cardiac death.
- Sitting in a hot sauna raises your heart rate to a level that resembles moderate exercise, even though you are sitting still.
- Reviews link regular sauna bathing to lower blood pressure and improved blood vessel function.
- The most consistently supported benefit is relaxation and stress relief.
- Heat is a real load on the body. Alcohol, dehydration, and certain heart conditions change the picture, so the safety section below matters.
How your body responds to sauna heat
At room temperature, only about 10 percent of the blood your heart pumps goes to your skin. In a hot sauna the skin warms, blood vessels near the surface widen, and as much as 70 percent of your circulation shifts toward the skin.
To keep your blood pressure stable while all those vessels are open, your heart beats faster. That is why a sauna session pushes your heart rate up into a range that looks a lot like a brisk walk, even though you are doing nothing but sitting. The common comparison among researchers is straightforward. If a person can walk at a moderate pace without getting winded, they can usually handle a sauna. When you cool down afterward, the vessels tighten and circulation returns to normal within a few hours.
We break down the heat behavior of a well built sauna in more detail in our look at the heat layers inside a sauna and the question of what sauna temperature is right for you.
Sauna and heart health
The single most cited piece of sauna research is a 2015 study published in JAMA Internal Medicine. Researchers followed 2,315 middle aged men in eastern Finland for a median of more than 20 years and tracked how often they used the sauna.
The results showed a clear dose response. Compared with men who used the sauna once a week, men who used it 4 to 7 times a week had markedly lower rates of dying from heart problems. Session length mattered too. Longer sessions, beyond 19 minutes, were tied to lower risk than short ones.
63%lower risk of sudden cardiac death
50%lower risk of fatal cardiovascular disease
40%lower all cause mortality
These are associations, not proof that the sauna alone caused the difference. The men who bathed most often may have shared other healthy habits. But the size of the effect, the length of the study, and the clear dose response have made it a landmark in the field. A 2018 review in Mayo Clinic Proceedings reached a similar conclusion across many studies and connected regular sauna use to lower blood pressure and better vascular function.
We go deeper on this in our breakdown of sauna bathing and cardiovascular health.
Blood pressure and circulation
The heat that widens your blood vessels also tends to lower blood pressure during and after a session. Some of the most interesting work came out of Japan, where studies on heart failure patients found that sauna sessions reduced the resistance the heart pumps against, improved how efficiently the heart worked, and lowered blood pressure. Patients felt better, and the measurements backed it up.
For most healthy adults the takeaway is simple. Regular heat exposure trains the cardiovascular system in a low impact way. It is one reason the sauna gets compared to light exercise rather than to a passive treatment.
Stress, sleep, and recovery
Ask a Finnish researcher what the sauna’s biggest health benefit is and the answer is usually relaxation. Professor Lasse Viinikka of the Finnish Sauna Society has made the point plainly. The short term effects on circulation matter less to long term health than the relaxation a sauna provides, and that relaxation is well documented.
Two mechanisms are proposed and they do not rule each other out. One is biochemical, tied to the release of mood related compounds in the brain during heat exposure. The other is simpler. A warm, quiet, dimly lit room with the smell of cedar and the sound of water on hot stones calms the nervous system. Either way, regular bathers report better sleep and lower stress, and a body of research supports the pattern.
More on this in our piece on saunas for stress, sleep, and mental health.
Breathing, muscles, and inflammation
Heat dilates the bronchi, which is why many people with mild asthma find the sauna eases their breathing. People with rheumatic joint pain often report relief on the day they bathe, though some notice it returns the next day. The heat also relaxes sore muscles, which is part of why athletes have used saunas for recovery for generations.
At the cellular level, heat triggers the production of heat shock proteins, which help repair and protect cells. The research here is still developing, but it is one of the more promising frontiers in understanding why heat exposure appears to do the body good. We cover it in our overview of heat shock proteins, inflammation, and immunity.
Who should be careful
Heat is a genuine load on the body. For healthy people that load is the point. For others it calls for care.
Alcohol and sauna do not mix. In studies of the rare deaths that happen in saunas, a large share of cases involved alcohol. Drinking raises the risk of dehydration, falls, and dangerous heart rhythms in the heat. This is a medical caution, not a social one.
Heart conditions warrant a doctor’s input. Moderate sauna use is generally well tolerated by people whose heart disease, high blood pressure, or heart failure is well managed and treated. If you have a cardiac condition, talk with your physician first.
Pregnancy. The long standing consensus in Finland, where nearly all pregnant women use the sauna, is that moderate sauna use during a healthy pregnancy is safe. Still, this is a personal call to make with your doctor.
Hydration and cold plunges. You lose water through sweat, so drink before and after. Jumping into cold water after the heat briefly spikes blood pressure, which most healthy people handle fine but which can be risky for those with heart conditions.
If you are on medication, the heat can change how some drugs behave. The effect is usually minor because sessions are short and the body returns to normal within a few hours, but beta blockers and a few other heart drugs are worth a quick conversation with your doctor.
Why the type of sauna matters
The research above was built on the traditional Finnish sauna. A stove, hot stones, and water poured over them to produce steam, running at roughly 150 to 195 degrees Fahrenheit. The men in the landmark study bathed at around 174 degrees. That detail matters, because the health data describes that specific environment.
BW Sauna Co. builds traditional Finnish saunas to that standard. Knotty and clear cedar interiors, a foil vapor barrier behind the cedar to keep moisture out of the framing, and heaters from IKI, Kuuma, and Harvia. It is the same construction logic the research was measuring, built for homes, cabins, and hospitality properties across the country.
If you want the practical side of bathing well, see our guide to how to use a traditional Finnish sauna and how long to stay in for the most benefit.
Frequently asked questions
Is the sauna good for your heart?
Research links frequent sauna use to lower rates of fatal heart disease. A 20 year Finnish study found that men who used the sauna 4 to 7 times a week had a 50 percent lower risk of fatal cardiovascular disease than men who used it once a week. These are associations, and people with heart conditions should check with a doctor first.
How often should you use a sauna?
The strongest benefits in the research showed up at 4 to 7 sessions per week. Two to three times a week still showed measurable benefit. There is no evidence that daily use is harmful for healthy adults.
How hot should a traditional sauna be?
Traditional Finnish saunas run roughly 150 to 195 degrees Fahrenheit. The landmark heart study centered on about 174 degrees. The right number is the one you can stay comfortable in for 15 to 20 minutes.
How long should a session last?
In the research, sessions longer than 19 minutes were tied to greater benefit than short ones. Most people land in the 15 to 20 minute range per round and take breaks to cool down between rounds.
Can you use a sauna every day?
Healthy adults can. Stay hydrated, avoid alcohol, and listen to your body. Frequent use is associated with the largest benefits in the research.
Is a sauna safe during pregnancy?
The consensus in Finland, where sauna use during pregnancy is near universal, is that moderate use during a healthy pregnancy is safe. Confirm with your doctor for your situation.
Sources
- Laukkanen T, Khan H, Zaccardi F, Laukkanen JA. Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events. JAMA Internal Medicine, 2015. View study
- Laukkanen JA, Kunutsor SK. Is Sauna Bathing Protective of Cardiovascular and Other Health Outcomes? Mayo Clinic Proceedings, 2018. View review
- Hussain J, Cohen M. Clinical Effects of Regular Dry Sauna Bathing: A Systematic Review. Evidence-Based Complementary and Alternative Medicine, 2018. View review
- Finnish Sauna Society. Sauna and Health Effects (based on talks by Professor Lasse Viinikka and Dr. Katriina Kukkonen-Harjula). sauna.fi
BW Sauna Co. builds traditional Finnish saunas to the standard this research describes. See saunas for sale, explore a custom home sauna, or read more across our sauna health library.
This page is for general information and is not medical advice. The studies cited describe associations, not guarantees. Talk with a physician before starting sauna use if you are pregnant or have a heart condition, high blood pressure, or another medical concern.
