Scientists studied the effects of sauna bathing on human physiology, and the results show that thermotherapy may be not only a cure, but also a tool for optimising our biology.

1. Sauna increases the growth of new neurons with BDNF

BDNF (brain-derived neurotrophic factor) is a growth factor, a cell signalling protein, which plays an essential role in our body. It affects ageing, behaviour, metabolism, energy levels, satiety, but also mental disorders, such as depression or schizophrenia. Most of you probably know it for its constructive activities - it assists in neuron formation and allows the growth of existing neurons. The decline in BDNF has an impact on our memory and contributes to the development of dementia and Alzheimer’s disease in the elderly. (1)

It has been shown that physical exercise leads to an increase in the signalling protein. However, there has been a new study recently, which implies that sauna bathing after training helps increase the production of BDNF in the brain, beyond the physical activity itself. (2)

2. Sauna helps treat depression via dynorphins

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. (3) One scientific study, performed on 28 mildly depressed participants, found that 4 weeks of regular sauna bathing 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. (4)

Although there are many complex mechanisms at play, it seems that the process is affected by dynorphins. These proteins are the counterpart of the well-known endorphins, which induce the pleasant feelings we experience after physical activity or sauna bathing. Dynorphins, on the other hand, cause feelings of discomfort. Imagine the moment you step outside your comfort zone - first you may experience discomfort, which is followed by positive feelings. Dynorphins are flushed out during the first phase, endorphins in the second. (5)

However, this effect of being flooded by pleasant sensations immediately after sauna bathing is rather short-lived. When it comes to long-term effects on our mental health, though, it is the lowering of chronic inflammation in the body that likely plays the main role.

This is because chronic inflammation works on a cellular level, we often cannot see it nor otherwise perceive it, and this causes lots of problems. If there is chronic inflammation running rampant in our body, we become more susceptible to mental disorders, such as anxiety, depression, and panic attacks, but also cancer, diabetes, cardiovascular and neurodegenerative diseases. (6) (7) (8) It is 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. (9) (10)

3. Sauna helps improve memory and concentration

There is a hormone that the body produces when we are in a stressful situation and that allows us to remember certain events better, for example violent attacks around the world or family tragedies. This hormone is none other than the famous norepinephrine. This is not its only role, though. When we practise cold therapy and expose our body to extreme cold, or practise sauna bathing and expose our body to extreme heat, this neurotransmitter is also produced. One study done on men showed up to threefold increase in norepinephrine levels in men who remained in an environment of 80 °C to the point of their subjective exhaustion. (11) Similar results were found in women. (12)

All this means that regular sauna bathing can help you feel much better not only physically, but also mentally. If you feel that cold therapy is not for you, try sauna for similar effects. There are many other mechanisms by which sauna affects the human brain. You will find out more in our next articles.

Bibliography:

1. https://www.foundmyfitness.com/topics/bdnf
2. https://pubmed.ncbi.nlm.nih.gov/21385602/
3. https://linkinghub.elsevier.com/retrieve/pii/S0140673613616116
4. https://journals.lww.com/psychosomaticmedicine/Abstract/2005/07000/Repeated_Thermal_Therapy_Diminishes_Appetite_Loss.21.aspx
5. https://pubmed.ncbi.nlm.nih.gov/12753076/
6. https://www.nature.com/articles/jhh2013111
7. https://www.foundmyfitness.com/topics/sauna#bibid-5ad51278fccd8755653f6c2adb2badc7
8. https://www.foundmyfitness.com/topics/sauna#bibid-f5f512eb3268c4f52b99af6e507c0469
9. https://www.nature.com/articles/npp201517
10. https://jamanetwork.com/journals/jamapsychiatry/fullarticle/1370458
11. https://pubmed.ncbi.nlm.nih.gov/2759081/
12. https://pubmed.ncbi.nlm.nih.gov/2830109/