Health effects of sauna on the body

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Sauna bathing is an inseparable part of many European cultures, where it has a long tradition. Saunas are used above all for rest and relaxation, and in some cultures it is a significant social occasion. Recently the culture of sauna bathing (as well as cold exposure) has started to spread in the Czech Republic, and so we have taken a look at what health benefits sauna bathing brings and in particular at the effects of the sauna on the body.

How does a sauna affect the human body?

By heating the body and raising the internal temperature of the body core we trigger a certain stress response. Our body's thermoregulatory response tries to prevent a further rise in body temperature and heat damage to the organism. Protective changes take place both at the level of organ systems (the neuroendocrine and cardiovascular system) and at the level of cells. In principle, during a sauna the blood vessels dilate, the heart rate rises and blood is driven into the peripheral parts of the body. At the cellular level we see an increase in heat shock proteins and transcription factors important for cell function.

During a sauna session the body also gradually starts to lose water in the form of sweat - depending on body build we sweat out an average of 50-80 ml of sweat every 5 minutes spent in a Finnish sauna at a temperature of 80-90 °C. If we keep to the upper limit of the recommended time in a Finnish sauna (max. 15 min), we lose between 250 - 400 ml of sweat.

Regular exposure to heat stress and the use of defence mechanisms gradually increases the resilience of some organs and is therefore a preventive measure against heart disease (heart failure), vascular disease (high blood pressure) and brain disease (e.g. Alzheimer's disease, dementia). The health effect on the heart and blood vessels is similar to intensive aerobic exercise, but without the effort and without strengthening the skeletal muscles. We also observe a reduction in cholesterol after long-term sauna use, fewer respiratory infections and increased levels of growth hormone.^{1, 2, 3, 4}

Sauna bathing improves sleep quality and supports recovery. The heat of the sauna increases heart rate and blood flow, much like exercise does. After a sauna, melatonin and growth hormone are released, which helps relaxation and recovery. Substances that relieve pain and calm the mind are also released during a sauna session. A study showed that a sauna in the evening before bed increases the length of deep sleep by up to 70 % during the first two hours. For maximum effect it is best to use the sauna in the evening with no further activity afterwards.⁵

So is sauna bathing healthy?

Using the sauna as a method for improving overall health and preventing disease is becoming ever more popular. Thorough research shows that regular exposure to heat stress has demonstrable health benefits, including increased resilience against heart and vascular diseases, such as heart failure, high blood pressure and neurological disorders of the Alzheimer's disease or dementia type.

Sauna bathing is an interesting alternative to traditional aerobic exercise, providing similar cardiovascular benefits without physical exertion. In addition, long-term sauna use may lead to a reduction in cholesterol levels, a lower incidence of respiratory infections and increased production of growth hormone, which athletes in particular will appreciate.

Given individual needs and state of health, however, we recommend discussing regular sauna use with a doctor. If you are interested in the downsides and risks associated with sauna bathing, we definitely recommend reading this dedicated article.

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References:

1. Patrick, Rhonda P, and Teresa L Johnson. “Sauna use as a lifestyle practice to extend healthspan.” Experimental gerontology vol. 154 (2021): 111509. doi:10.1016/j.exger.2021.111509
2. Heathcote, Storme L et al. “Passive Heating: Reviewing Practical Heat Acclimation Strategies for Endurance Athletes.” Frontiers in physiology vol. 9 1851. 20 Dec. 2018, doi:10.3389/fphys.2018.01851
3. Laukkanen, Jari A et al. “Cardiovascular and Other Health Benefits of Sauna Bathing: A Review of the Evidence.” Mayo Clinic proceedings vol. 93,8 (2018): 1111-1121. doi:10.1016/j.mayocp.2018.04.008
4. Kunutsor, Setor K, and Jari A Laukkanen. “Does the Combination of Finnish Sauna Bathing and Other Lifestyle Factors Confer Additional Health Benefits? A Review of the Evidence.” Mayo Clinic proceedings vol. 98,6 (2023): 915-926. doi:10.1016/j.mayocp.2023.01.008
5. Putkonen, P.T.S., Eloma, E., (1976). Sauna and physiological sleep: Increased slow-wave sleep after heat exposure. Sauna Studies. pp 270-279. Vammala. ISBN: 951-95328-0-3