The healing, cleansing, purification and spiritual practices of bathing the body in heat dates back thousands of years and has been observed in many cultures including; Russian banya, Turkish hammams, Native American sweat lodges and Finnish saunas.
By using short-term passive exposure to extreme heat, these ancient practices work by eliciting mild hyperthermia (an increase of the body’s core temperature over 37.5°C up to ~39°C) and triggering the body’s thermoregulatory response.
Originally, there was only one kind of sauna; the air was heated (convection) and then that heat transferred to the user’s skin (conduction). Then, around the 1980’s technological innovation introduced a new option for widespread use; the infrared sauna; the radiant infrared energy heats the user’s body directly (conversion).
This brings us to today, where the heated discussion (pun intended) around what is better - a traditional Finnish sauna or an infrared sauna - rages on.
Before we wade into that, here’s an overview of what happens in the body during heat exposure.
The body’s response to heat
The information in this section has been obtained from the excellent paper ‘Sauna use as a lifestyle practice to extend healthspan’ (Patrick 2021, 1).
While there are different ways to heat the body, the effects of heat are the same (well, very similar!). When exposed to high temperature stress, there’s “a rapid, robust response that affects primarily the skin and cardiovascular systems. The skin heats first, rising to approximately 40°C, followed by changes in core body temperature, rising slowly from 37°C to approximately 38°C and then increasing rapidly to approximately 39°C”.
In response, the heart begins to work harder, pumping 60-70% more blood, of which approximately 50–70% redistributes from the core to the skin. This helps facilitate sweating, with people losing ~0.5kg during a typical dry sauna session. Blood plasma also increases, to act as a reserve source of fluid for sweating and helping to cool the core temperature & promote heat tolerance, which further increases the heart’s work output.
By continually, consistently triggering the heat stress response we acclimate the body to heat and optimise how our body responds to future heat exposure. This occurs through a process known as hormesis, the principle of “some stress is good, but more is not better” (2), that triggers an array of protective mechanisms that repair damage from the current exposure and provide protection against subsequent exposures (1). Other examples of hormetic stress include cold exposure, intermittent fasting, HIIT and even problem solving while gaming (3).
It’s this process of dissipating heat and returning the body to normal core temperature that gives rise to the many benefits of sauna.
The different types of sauna
While sauna traditionalists and the Finns (who have one of the first descriptions of sauna recorded in 1112AD) will likely disagree, for the purpose of this article I’m going to classify saunas into three categories; dry heat, wet heat and infrared.
Dry Heat Sauna
This is a traditional Finnish sauna, where the air in the unpainted wooden room is heated to between 70°C to 100°C (optimally 80°C to 90°C), using either a wood fire or electric heater (with or without hot rocks). While people do throw water onto the heater rocks to increase the humidity (a practice called löyly in Finland), the humidity in a dry sauna remains low, around 10-20%. Dry saunas heat the air around you, which then heats your body, causing your core temperature to increase, making you sweat. The sweat then evaporates and cools your body, acting as a natural cooling mechanism.
Wet Heat Sauna
Better known as a steam room, wet saunas are heated using a steam generator to create humidity levels ranging between 50-100% in an almost airtight room, to create a warm, moist environment. Although steam rooms are not as hot (typically 38°C to 48°C), the high humidity keeps sweat from evaporating, making them feel hotter than a dry sauna. The moist air in a steam room can help to open up the airways and clear nasal congestion, making wet saunas better suited for people with respiratory issues such as asthma, allergies, or congestion (4).
Infrared Sauna
Infrared saunas, which hit the market around the 1980’s, raise your core temperature by emitting thermal radiation from special lamps and/or heaters, which heats the body directly (and warms the surrounding air slightly). As they operate at a lower temperature compared to dry saunas (between 45°C and 70°C), they offer a more ‘relaxing’ heat and it can be easier to stay in them longer.
There are two types of infrared saunas available; far or full spectrum infrared. Far spectrum saunas emit radiation in the 0.030mm to 1 mm wavelength, which are experienced by the body as gentle radiant heat and can penetrate up to a depth of ~4 cm (5). Full spectrum infrared saunas emit near, mid and far spectrum radiation. While the far spectrum elevates the core temperature and penetrates deeply, near infrared (red light therapy), using special light bulbs, is absorbed just below skin’s surface and can be beneficial for skin health and wound healing (6), while mid spectrum penetrates slightly deeper and supports the action of the far infrared radiation. In this article we’re going to focus solely on far spectrum infrared, not near- or mid-infrared, as it offers similar benefits to the other forms of sauna.
So what is better?
Pros and Cons of Traditional, Steam and Infrared Sauna
Full disclosure, I’m not a techy person or a medical specialist. My recommendations are based on the physical pros and cons of each type of sauna, from a broad scan of the available information, and my own experiences.
Traditional Sauna
Pros
Quicker sweat production (~15-20 mins)
More intense experience limiting the duration (~20 mins)
Closer experience to moderate exercise
Increases blood circulation and improves heart health
Increases white blood cell count and strengthens the immune system (7)
Reduced incidence of respiratory infections such as colds and pneumonia (8)
Reduce pulmonary congestion associated with COPD (8)
Protect brain health through elevating brain-derived neurotrophic factor (BDNF)
Promote longevity via the release of heat shock proteins (HSP)
Help lower inflammation
Increase human growth hormone
Cons
The very high temperature (> 90°C) can feel uncomfortable
The dry heat can irritate the airways and lungs
May not be suitable if you have respiratory issues such as asthma, allergies, or congestion
It is important to hydrate properly prior, to avoid overheating and heat stroke
Steam Sauna
Pros
The high humidity levels help soothe an irritated respiratory system
Helps opens up congested airways and flush mucus build-up
Improves the course of a common cold and gives immediate relief of symptoms
Improves blood circulation
Lower temperature (< 50°C) of the steam sauna may be more comfortable
Cons
The high humidity keeps sweat from evaporating, making them feel hotter than a dry sauna
Increased risk of dehydration
The high humidity and moisture may aid the growth of bacteria
Infrared Sauna
Pros
Slower sweat production (> 20 mins)
Gentler sauna experience allowing you to remain in for longer (~30-45 mins)
Heat penetrates deeper into the body, helping to reduce muscle and joint stiffness
Activates white blood cells and strengthens the immune system
Improves blood circulation & heart health
Promote brain health
Cons
Not effective in relieving respiratory congestion like steam rooms
The dry heat may irritate the airways and worsen a cough
Greater risk of dehydration
Note: While the list of benefits from a traditional sauna appears longer, there is limited infrared-specific research, and what is written out there often has a very clear bias toward infrared saunas (i.e. their website sells them!), so I’ve erred on the side of caution with the dot points. Air temperature does not equal core temperature, so despite the different ways of heating the body - dry sauna, wet sauna and infrared sauna - they have all been shown to increase core temperature, leading to the incredible benefits of sauna use.
Summary
What would I choose? If you’d asked me just 6 months ago I would have picked a traditional sauna, almost exclusively. These days, after diving into the research further, and experimenting more myself, I would say it depends.
If I’m short on time, or looking for a more ‘extreme’ sauna session, maybe to work on my breathing and stress response, I would use a traditional sauna. Whereas, if I’m looking for a gentler, perhaps more meditative sauna experience, or bathing before bed, I would use an infrared sauna. I’m fortunate enough to have access to a facility that offers both.
Try the different sauna methods for yourself and discover what works for you.
Self-Exploration
Dr Rhoda Patrick - https://www.foundmyfitness.com/topics/sauna#hormonal-and-metabolic-function
Huberman Lab - https://www.hubermanlab.com/episode/the-science-and-health-benefits-of-deliberate-heat-exposure
Certified Saunas (Matt Justice) - https://certifiedsaunas.com/blog/ (join the Facebook group too)
References
Interested to learn more about breathing or cold and heat exposure? Explore my coaching program or contact me.
Enjoyed this article? Sign up to my newsletter or follow me on Facebook or Instagram
Disclaimer
Please note that this information should not be seen as medical or therapeutic advice and that you should talk to your healthcare practitioners prior to lifestyle changes.
Heat exposure training (including sauna) is not recommended for those who are pregnant or looking to conceive. People with acute illness accompanied by fever, or inflammatory skin conditions should avoid sauna use. People taking any kind of medication, anyone with a diagnosed cardiovascular or kidney condition or those with low blood pressure, should consult a healthcare professional before using the sauna. Sauna users should take care to drink sufficient fluids prior to and after sauna sessions and should consume electrolyte-rich foods post-sauna use. Alcohol consumption before or during sauna use should be avoided.
Heat exposure has notable, but reversible, effects on male sperm and fertility measures including reduced sperm counts and motility. These measures have been shown to return to normal, within six months of ceasing sauna use.
Comments