The word “sauna” is Finnish, and Finnish people tend to prefer that this term is reserved for traditional Finnish sauna. Colloquially, however, sauna can mean a variety of forms of passive heat exposure, including ones from other cultures (e.g., Russian banya, Turkish hammam, Jewish shvitz, Korean jjimjilbang) and ones that have proliferated due to new technologies (e.g., electric/infrared saunas).

Practically speaking, saunas can vary in many notable ways:

• Temperature
• Relative humidity
• Heating method
• Duration of use
• Frequency of use
• Whether intervallic “cooling off” periods are employed and what they entail (e.g., cold plunge, rolling in snow, sitting in a cooler room)
• Design and construction of the structure itself
• Additional practices like the use of veniks (“bath brooms” made of birch) in Russian banya practice

The history of sauna goes back thousands of years, and modern versions of sauna have certainly evolved since people in Finland first dug pits in the ground where they heated stones on a wood fire and threw water on the hot rocks to create a heated space. Pronounced “SOW (rhymes with “wow”)-nah” by Finns or “SAW-nah” by most English speakers, the word “sauna” is perhaps the only Finnish word that has entered the English language; it refers to both the practice of sauna bathing and the physical structure where bathing takes place. As Finnish people migrated all over the world, they brought their sauna traditions to many different cultures, and Finnish sauna culture is recognized by UNESCO.

The traditional Finnish sauna is believed to cleanse and refresh the body and mind and is considered an important cultural and spiritual ritual (the old saying “saunassa ollaan kuin kirkossa” means “behave in sauna as you would in church”). Different regions and even different Finnish households may have slightly different sauna practices, but most homes, hotels, apartment complexes, student dorms, gyms, and public halls in Finland have sauna facilities that are used daily or at least weekly.

After a quick shower to remove surface sweat and grime, the Finnish sauna ritual begins with a dry phase, during which bathers get accustomed to the heat from the wood-fired or coal-fired stove topped with hot stones. Individual bathers can choose their level of heat by moving closer to or farther away from the stove, by sitting on the lower benches (cooler air) or higher benches (hotter air), or by placing a cold wet towel on the head or the back of the neck. In fact, many Finns wear hats in the sauna, which shields the head from the heat and increases overall comfort.

In the next phase, water is thrown on the hot stones to create löyly, the heated steam atmosphere that surrounds the bathers and condenses on the skin along with the sweat from the dry heat phase. This “sweating from the inside and condensing from the outside” is considered a purifying ritual that cleanses and promotes good health. Many Finns also use a “bath broom” or small switch made of birch twigs, called a vihta, to lightly swish or beat the skin to enhance the stimulating sensation and promote circulation, alongside washing with water, soap, and shampoo.

The cooling phase of sauna usually involves a cold plunge in water (a pool, lake, pond, or a hole in the ice in winter) or a roll in the snow outside, though a cold shower can also suffice. The hot/cold contrast is invigorating and is an important part of the traditional Finnish sauna experience. The hot/cold phases can be alternated several times, according to personal taste.

After sauna, it is also common to have a small snack, like a cool drink and a sandwich or sausage, to rehydrate, refuel, and relax with body and mind cleansed and soothed.

Overall, sauna and exercise both cause an increase in heart rate, blood pressure, sweat rate, and blood flow to skeletal muscle and skin. Exercise definitely increases respiratory rate, and sauna sometimes does the same. Additionally, they are similar in their long-term benefits, improving blood pressure, endothelial function, and arterial stiffness.^[11][12]

At the time of creation of this page, there are two studies that have directly compared exercise and sauna:

A 2019 study in 19 healthy participants compared a 25-minute session in a traditional Finnish sauna at 93°±3°C and 13%–20% relative humidity to a 6-minute session on a stationary bicycle ergometer (starting at 50 watts and increasing by 10 W every minute to a maximum of 100 W).^[13] Interestingly, despite interventions with very different durations, the outcomes measured followed very similar trends and reached almost identical final values: systolic and diastolic blood pressure increased by about 15 mmHg in both groups; heart rate increased by about 43 and 53 bpm in the exercise and sauna group, respectively; and the product of systolic blood pressure and heart rate (a correlate of cardiac oxygen consumption) increased by 107% — which was similar to the increase observed during exercise. Similar to exercise, blood pressure dropped below presauna levels within 30 minutes of the end of the sauna bath.

A 2022 crossover study in 10 healthy women compared moderate-intensity exercise (heart rate between 55% and 70% of maximal heart rate) on a stationary bike, infrared sauna at 60°C (140℉) and less than 20% relative humidity, and resting at approximately 25°C (77℉) , with each intervention applied in three 15-minute intervals separated by 5 minutes of rest at 25°C (77℉).^[9] This trial found that tympanic temperature (a proxy of core temperature) was significantly higher in the sauna group and that respiratory rate was significantly higher in the exercise group. Interestingly, heart rate, blood pressure, mean arterial pressure, heart rate variability, and transient arterial stiffness did not differ between the sauna and exercise groups. There are many reasons for these unremarkable findings, but it’s possible that neither intervention was sufficiently physiologically stressful to meaningfully distinguish it from the control condition.

Overall, it seems that sauna can provoke cardiovascular responses that are similar to exercise, although the specifics of the sauna intervention matter a lot. It’s also important to note that, unlike exercise, sauna does not actively engage skeletal muscles and therefore wouldn’t be expected to cause improvements in muscle mass, muscle strength, or muscle endurance unless paired with an exercise training program.

Exercise and sauna both benefit the cardiovascular system, and a few studies have shown them to be especially beneficial when combined. In a randomized controlled trial from 2022, people with low activity levels and at least one cardiovascular disease who did a 1-hour exercise regimen (comprising both resistance and aerobic training) followed by a 15-minute sauna session thrice weekly had considerably better improvements in VO₂max, systolic blood pressure, and total cholesterol than people who only exercised.^[14] Similarly, a study from 2015 found that although 5 days of sauna alone was sufficient to improve markers of cardiac function in people with heart failure, adding approximately 1 hour of exercise to the regimen improved these outcomes even more.^[15]

Of course, these studies alone don’t tell us whether the sauna-exercise pairing is effective because they are synergistic (i.e., exercise potentiates the effects of sauna and vice-versa), or whether it’s simply because the participants in the combined treatments groups received two interventions instead of one. Regardless, both exercise and sauna seem to be similarly worthwhile strategies for managing cardiovascular disease.

The notion that sauna may support longevity is largely supported by a series of studies on a cohort of 2,315 middle-aged men in Finland, which found that sauna use was associated with a dose-dependent reduction in cardiovascular and all-cause mortality; people who used sauna the most (4–7 times per week for a duration of approximately 19 minutes or more per session) had a 50% reduction in risk for these outcomes.^[16] A similar dose-dependent relationship was also present for sauna use and age-related neurodegenerative diseases like dementia and Alzheimer’s disease, with the most frequent sauna bathers having a 65% reduced risk of these conditions.^[17]

Broadly speaking, it seems that sauna supports longevity in a similar way to exercise — by acting as a mild physiological stressor, it promotes cardiovascular, neurological, and immune function. In other words, it’s a hormetic stressor that promotes physiological responses that help bolster body systems that are most likely to falter during aging.

More specifically, the hormetic effects of sauna are the result of its influence on the following:^[6]

• Heat shock protein expression: Sauna (and heat generally) increases cellular concentrations of heat shock proteins, a broad class of proteins that regulate a number of cellular processes related to gene expression and cell division and also recycle and repair other proteins that are damaged. There’s mechanistic evidence that they may help prevent neurodegeneration and muscle atrophy, and some observational research in humans has correlated heat shock protein levels with small (approximately 1 year) increases in lifespan.^[18]
• Nrf2 activity: Nuclear factor erythroid 2-related factor (Nrf2) regulates antioxidant and immune functions in cells, and heat seems to increase its expression, at least in human skeletal muscle.^[19]
• IL-6 and IL-10 activity: Similarly, sauna (and exercise) increases circulating levels of interleukin 6 and interleukin 10 (IL-6 and IL-10, respectively). The former is associated with increased inflammation, but it also increases levels of the latter, which has anti-inflammatory effects. Given that low-grade inflammation is a defining characteristic of many chronic diseases, it’s possible that sauna’s effect on inflammatory signaling may lead to ultimately more favorable levels of inflammation in the body.

There aren’t any studies that directly compare different types of sauna, so it’s not clear whether one is better than the other. Because they heat exclusively with infrared light, infrared (IR) saunas can produce similar increases in body temperature while creating lower ambient temperatures.^[9] Theoretically, IR saunas may be able to penetrate the skin and act on deeper tissues, but it’s not clear whether this garners any extra benefits.^[10][1]

Given that IR sauna can produce heating effects similar to traditional Finnish sauna but at lower ambient temperatures, it would be interesting to see how much the sensation of heat on the skin modulates the apparent benefits of sauna.