Since early times, sauna bathing has been enjoyed by many people in various forms throughout the world, and is now commonly used in health fitness and medical facilities. Over thousands of years, sauna has evolved to meet the needs of current cultures throughout generations. What began as tribes sitting around a fire pit in a hole in the ground has evolved into high tech sauna devices used for everything from bad skin to cancer.
Very primitive steam baths were used by Vikings, Aztecs, North American Indians, ancient African people, and Mayans.1, 2, 3 The practice of bathing in hot air fumes reached to Syria, Greece and Egypt.4 Sauna bathing with supersaturated steam was especially widely practiced among the ancient Slavs and in the eastern part of the Scandinavian Peninsula.
Over 2000 years ago, peoples of Finland employed hot steam baths with hot dry baths and the Finnish sauna was created. It gradually gained popularity throughout Europe, while similarly, the “banya” steam sauna in Russia developed. In Japan, saunas of low temperature (40-45° C) with high relative humidity (RH; 90 to 100%) have long been used as steam baths.
The Finnish sauna has become one of the most popular types of saunas in the world. Finland, with a population of five million, has close to one million saunas. Most Finns take a sauna bath weekly and grew up hearing the adage:
“If the sauna, schnapps, and birch tar don’t help, then death is near.”
There are several distinct types of saunas: steam bath, dry-heat sauna, infrared saunas, and far-infrared (FIR) saunas. When the term “sauna” is used in the medical literature without any modifiers (e.g., infrared), it generally refers to the Finnish steam sauna.
Finnish steam saunas use a wood-paneled room with wooden benches and a radiant heater that keeps the temperature between 70 and 100°C (158-212°F) with a face level temperature of 80-90°C (176-194°F). Steam is produced by pouring water over heated rocks. Generally enough steam is produced to create high humidity. The standard length of a Finnish sauna is 5-20 minutes in the sauna, followed by cold immersion (swim or shower) and a period of room temperature recovery before repeating. In a single sauna session, this pattern is repeated 2-3 times.
Dry-heat saunas are essentially the same as Finnish steam saunas; however, the room used is dry, so steam is not produced. The procedure for these saunas is also roughly the same as that described for Finnish steam saunas.
Infrared saunas utilize a different heating element and typically do not achieve the same temperatures as the radiant heat saunas. There are also no hot rocks on which to splash water for humidity. There are two main types of infrared saunas: infrared and far-infrared (FIR).
Infrared saunas use incandescent infrared heat lamps to produce heat. They emit primarily near-infrared wavelengths, with lesser amounts of middle-infrared. They also emit a small amount of red, orange and yellow visible light. This type of sauna also provides warming and stimulating color therapy. While traditional saunas require high temperatures for copious sweating, infrared penetrates the skin and heats from the inside as well as on the skin. This means the air temperature in the sauna can remain cooler, yet one sweats plenty at this lower, more comfortable temperature.
An infrared sauna takes approximately 15 to 20 minutes for the emitters to come up to temperature (approximately 115 to 135°F). When using the infrared, the bather waits until the infrared emitters in the room are running at full heating potential. The bather then sits next to the emitters to allow the body to be heated directly by the infrared radiant heat. The bather will use the room for 20 to 30 minutes to induce a deep sweat – once this is achieved, the bather has completed the sauna practice. The bather can achieve a more direct effect of heat therapy to portions of the body based on how closely that portion of the body is exposed to the actual emitters.
Far infrared saunas use ceramic or metallic elements for heating that mainly emit in the far infrared range. These appear to be superior to other types of sauna in the elimination of waste from the body. Sweating is nature’s way of removing and eliminating wastes and toxins that have been stored in body tissues. Far-infrared heaters stimulate this process at low, comfortable temperatures. Normal sweat is 97-99% water; sweat induced by Far Infrared Therapy is only 80-85% water. The rest is composed of endogenous and exogenous toxins that are being mobilized, such as toxic elements, chemicals, urea, various cholesterol, and lactic acid.
Because it activates many of the same physiological responses as physical exercise, sauna bathing has been used not just for bodily detoxification, but has also been regarded as a type of physical training and is commonly used among athletes.5
It has been shown that during a sauna session, the adult body burns about 300 kcal – which is equivalent to the energy needed for a 3-4 km run.6 During sauna bathing, the heart rate increases to about twice its resting rate.7, 8 This is because the sympathetic nervous system and hypothalamus-pituitary-adrenal hormonal axis are intensely activated to compensate for the excessive increase of body temperature – resulting in muscle relaxation and reduced mental stress.9, 10
Some studies suggest that regular sauna bathing may actually lower the blood pressure in patients with hypertension.11,12 Under the influence of sauna, the frequency of lung ventilation significantly increases 13, 14 and as such, regular sauna generally increases lung vital capacity (VC), peak expiratory flow rate (PEF) and also forced expiratory volume in the first second (FEV1).15
There are numerous other beneficial physiological effects of sauna, particularly relaxation of the muscles and a release of toxins and other impurities through the pores that are opened via heat treatment.16, 17, 18 Removal of such toxic residues from the body provides increased and improved cellular function, thus enhancing overall health and well-being. Improved circulation allows more oxygen and nutrients to reach injured areas of the body and help reduce pain and speed up the healing process.
Sauna bathing has been used as thermal therapy to treat pain and other symptoms of rheumatic disease, although clinical studies are limited. Sauna has been shown to reduce pain sensation by direct action on both free-nerve endings in tissues and on peripheral nerves.19, 20, 21 Exposure to sauna heat during sauna bathing raises the skin temperature of the bather near the hot pain perception threshold and enhances sympathetic activity.
Most often, sauna bathing is a procedure applied for biological restoration in athletes both professional and amateur.22, 23, 24 Studies also document the effectiveness of sauna therapy for persons with hypertension, congestive heart failure, and for post-myocardial infarction care.25 Some individuals with chronic obstructive pulmonary disease (COPD)26, chronic fatigue27, and chronic rheumatic pain28 also find benefit. Existing evidence supports the use of saunas as a component of purification or cleansing protocols for environmentally-induced illness.29, 30
Generally, sauna bathing has a historic proven record of safety. There are only a few circumstances in which sauna may be contraindicated, or should be performed with caution.
Sauna bathing is contraindicated during high-risk pregnancies and for patients with unstable angina pectoris, recent myocardial infarction, and severe aortic stenosis. Blood pressure may decrease after sauna, sometimes resulting in syncope. As sauna bathing leads to skin sweating-induced fluid loss, hydration and electrolytes should be restored. Alcohol intake while sauna bathing can create serious health risks and should be avoided.
But studies suggest that for most people, sauna bathing is a recommendable health habit with numerous benefits.