The practice of sauna is ancient, with evidence that goes back thousands of years. It can vary in form and execution in different cultures of the world. The most popular variant, which we all probably know, is the Finnish sauna. Another form, less common but of increasing popularity, is the sweat lodge - a traditional purifying ritual of Native Americans. There exist different variants, depending on the culture.

The purpose of this practice is virtually the same everywhere, however. It is about purifying the body and mind, and some peoples also recognise its spiritual dimension. We will now have a look at the measurable benefits of sauna, while you can also look forward to different protocols and our personal experiments in next articles.

Recently, sauning has become literally a hot topic in the field of scientific research. It has been shown that hyperthermia is a great way to increase your life expectancy, slow down ageing, and improve your health in general.

The benefits of sauning

Over the last couple of months, we have described in great detail the benefits of cold therapy for women in all the different stages of their lives. Also, we have produced an e-book on the topic. Heat therapy has similar final effects as cold therapy, only the way is different. Both of these paths have their own merits and you can even combine them freely. If you cannot go to a public sauna during the pandemic, you might consider getting one for your home after reading these lines.

Reducing inflammation and effects on depression

The incidence of depression is about twice as high among women as among men, with a yearly prevalence of 5.5 % and 3.2 %, respectively. (1) Most of you, who take an interest in biohacking, your own biology optimisation, or work as trainers in different areas, know that inflammation is a big issue. Many people know of acute inflammation which can occur as the consequence of a small injury, for example, where we can observe redness and swelling. Some of you, however, might also be aware of chronic inflammation. In biohacking, we look for ways of optimising the levels of inflammation in the body and reduce the chronic kind. The problem is that chronic inflammation happens on the cellular level and we often cannot see or distinguish it. If it runs rampant in our body, we become more susceptible to mental disorders, such as anxiety, depression, and panic attacks, but also physical ailments - cancer, diabetes, cardiovascular and neurodegenerative diseases. (2) (3) (4) It has become evident that there exists a causal link between inflammation and depression. 

In several randomised double-blind studies, scientists injected volunteers with endotoxins and interferon gamma which led to an increase of proinflammatory cytokines (including IL-6). After administering these compounds, thus causing increased inflammation in the body, an acute increase in anxiety and depression was observed in the subjects. (5) (6)

In another study, performed on 28 mildly depressed participants, it was found that 4 weeks of regular sauna practice led to an improvement of depression symptoms in these individuals, compared with the control group whose participants were kept at bed rest instead of sauning. (7) This is fascinating also because we see similar results in cold therapy, only the way is different, and for some more accessible and pleasant. Personally, I struggle more with thermotherapy than with cold therapy. That is why it is important to listen to your individual body and choose your own path.

Even more impressive are the findings of a different study with 30 participants with diagnosed depression. The subjects were exposed to whole-body hyperthermia treatment. During the process, their body temperature was increased to 38.5 °C which had a demonstrable antidepressant-like effect. These effects persisted for up to 6 weeks after the termination of the experiment. (8)

Cognitive functions & neurogenesis

Cardiovascular problems usually affect the blood supply to the brain and the peripheral nervous system, rendering it insufficient, which in turn affects cognitive functions. A decrease in cognitive functions also acts as an important factor in our predisposition to various neurodegenerative diseases including Alzheimer’s disease. (9)

Just as occurs during exercise or in a short-term physical strain, the level of one particular neurotrophic factor, BDNF, increases in our brain when we expose ourselves to heat in the sauna. This molecule is absolutely essential for our health and everything we do. If it decreases, so does our energy level and our memory. This protein acts on neurons in both the central and peripheral nervous system and encourages growth of new neurons. At the same time it reduces anxiety and depression and improves our overall mental wellbeing. (10) (11) BDNF also affects our appetite - the feeling of being satiated or not. There are several different ways to increase this factor - from sauning and cold therapy to medicinal mushrooms, like Lion’s mane, for example.

Endogenous drug-like factors

Endogenous drug-like factors, such as norepinephrine or prolactin, have an effect on our mental health in the long run. The former enhances alertness, attention, and focus. The latter encourages myelin growth, which speeds up the functioning of the brain, an important aspect of damaged nerve cell repair. Prolactin is a peptide hormone produced by the pituitary gland and it stimulates the production of milk. During pregnancy, the levels of this hormone increase significantly and, if a woman breastfeeds, they remain high several months after childbirth. (12) (13)

One Czech scientific study focused on analysing the heart rate of 8 males and 8 females in order to determine whether differences between the sexes exist. They found that hyperthermia resulted in a much more elevated heart rate in women than in men. Sauna induced prolactin production was also higher in women. (14) However, the production of this hormone in response to physical strain or psychological stress is the same in both sexes.

In conclusion

Most studies which demonstrate the benefits of sauning include a certain protocol that dictates for example three 10-20 minute rounds of exposure to temperatures of 70-90 °C with 10-30 minute breaks in between for the body to adapt. Sweat lodges, on the other hand, are entirely different. The whole process can go uninterrupted for 2 or 3 hours. I have that experience and, honestly, I thought I was going to die there. When I crawled out after 2.5 hours, I thanked god for being alive. When I looked in a mirror, though, I looked 20 years younger. I am not joking, I looked like a 13-year-old! But I never went back. It is hard to say whether this technique is safe. Personally, I do not think so, although I respect that it is a tradition of Native Americans. Even here, in the Czech Republic, there are now many people who can guide you through the process safely. It is simply a different way of exposing yourself to heat. 

At Systers, we encourage stress microdosing and sustainability. If you administer cold or heat in doses, the chances grow that you will persevere and practise regularly.

Bibliography:

1. https://linkinghub.elsevier.com/retrieve/pii/S0140673613616116
2. https://www.nature.com/articles/jhh2013111
3. https://www.foundmyfitness.com/topics/sauna#bibid-5ad51278fccd8755653f6c2adb2badc7
4. https://www.foundmyfitness.com/topics/sauna#bibid-f5f512eb3268c4f52b99af6e507c0469
5. https://www.nature.com/articles/npp201517
6. https://jamanetwork.com/journals/jamapsychiatry/fullarticle/1370458
7. https://journals.lww.com/psychosomaticmedicine/Abstract/2005/07000/Repeated_Thermal_Therapy_Diminishes_Appetite_Loss.21.aspx
8. https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2521478
9. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1748-1716.1994.tb09689.x
10. https://pubmed.ncbi.nlm.nih.gov/23897689/
11. https://www.sciencedirect.com/science/article/abs/pii/S0306453010001423?via%3Dihub
12. https://linkinghub.elsevier.com/retrieve/pii/S0006899304006493
13. https://www.jneurosci.org/content/27/8/1812
14. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1748-1716.1994.tb09689.x