If you Win the lottery, buy a sauna
Generally I’m sceptical of wellness activities that have a long list of benefits, but when it comes to sauna, I make an exception.
If I won the lottery I’d buy myself and my immediate family a sauna each. Why? Apart from sleep, it’s one of the best health interventions I’ve come across yet. Frequent sauna use (4-7 times weekly) has been shown to lower the risk of premature death by 40%, the risk of death from cardiovascular-related causes by 50% (1) and to lower the risk of developing dementia by 66% (2), even when considering age, activity levels, and lifestyle factors (1).
Those three incredible health benefits are convincing enough for me, but there are so many more benefits of using the sauna regularly.
Side note 1: the Finnish study the results come from, the Kuopio Ischemic Heart Disease Risk Factor Study (KIHD), is incredible in itself. It involved studying nearly 3,000 men and more than 1,000 women over 20 years, and produced over 400 original peer reviewed research papers (3).
Side note 2: If you’re new to sauna or would like to learn about the different types and how to use them, I unpack all that in this article.
TL;DR
Short on reading time, don’t need much convincing or you simply love a good list, here’s 9 reasons why you should get into a sauna more often this year:
Improves heart health
Improves brain health
Lowers blood pressure
Reduces stress
Decreases inflammation
Improves exercise recovery
Helps build & maintain muscle
Provides deeper sleep
Detoxifies the body (there’s a caveat)
If you are looking for the research behind the benefits rather than a random list, or you simply like to read, let’s unpack my favourite benefits of using a sauna regularly below.
Here’s why you should sauna regularly
The biggest takeaway from the Finnish KIHD study is that the benefits of sauna use are dose dependent; the more frequent you sauna, the greater the benefit. Note: frequency is very different to duration; beyond a therapeutic duration of ~15-20 mins, longer saunas are not better!
Improves heart health
During a sauna, heart rate can increase to between 100 to 150 bpm (4) and the heart has to work significantly harder to pump more plasma-rich blood away from the core to the skin, increasing overall blood circulation. This response is why sauna use is seen as an exercise mimetic, with a similar physiological response to that of moderate-vigorous physical exercise, making it a helpful activity for people who are unable to engage in physical activity (5).
This improvement in cardiovascular system health is one of the key contributing factors to frequent (4-7 times per week) sauna use helping decrease the risk of sudden cardiac death (63%), fatal coronary heart disease (48%), fatal cardiovascular disease (50%). Additionally, when combined with aerobic exercise, frequent sauna use has an even greater effect on lowering cardiovascular-related mortality and all-cause mortality (4).
Lowers blood pressure
Due to its impact on the cardiovascular system, frequent sauna use has been shown to improve vascular compliance and increase endothelial function (the cells responsible for vascular tone and blood flow). This helps to lower the risk of developing high blood pressure by 46%, providing hope that sauna use may be helpful in addressing or even preventing high blood pressure (4).
Improves brain health
With every beat of our heart 20-25% of our blood is carried to and from our brain, delivering a steady flow of oxygen, glucose and other key nutrients, while carrying away CO2, lactate and other metabolic waste, including amyloid-beta plaques (involved in the acceleration of Alzheimer’s disease, 6). By increasing our overall blood circulation, a sauna session also increases blood flow to and from the brain, helping to keep it healthy and functioning optimally.
Additionally, heat stress increases the expression of brain-derived neurotrophic factor (BDNF), a protein that is involved in preserving already-existing nerve cells and encouraging the growth of new nerve cells and synapses (7), helping to maintain brain plasticity and support healthy brain function. Incredibly, just a 20 minute bath in 42°C water was enough to raise BDNF levels 66% (4).
Lastly, heat exposure triggers a protective adaptive response through the release of heat shock proteins (no surprise there). These proteins preserve the structure and prevent the clumping together of other proteins within a cell. They’ve been shown to promote longevity and protect against neurodegenerative and cardiovascular diseases (4).
These influences on brain function and health are likely one of the key factors behind frequent sauna of 4 to 7 times per week use being shown to have a 66% lower risk of developing dementia and a 65% lower risk of developing Alzheimer’s disease (4).
Reduces physiological stress
Heat exposure triggers a stress response in the body, sharply raising cortisol levels during the sauna session, especially for infrequent or first-time users. However, a 2021 study involving 4 sauna sessions of 12 min (90−91°C), with a 6 min cool down break (including 1 min in 10−11°C water) saw up to a 30% decrease in serum cortisol levels post-sauna, indicating that more frequent sauna users adapt to the heat stress. Interestingly, they found that the higher the baseline cortisol levels, the greater the decrease in cortisol (8).
As outlined above in the body’s response to heat, this repeated heat stress exposure triggers hormesis, a mild, tolerable stress response that stimulates the body, helping it to positively adapt to the stressor, making long-term sauna use a great way to destress and relax.
Decreases inflammation
Inflammation is an important part of our body’s immune response, however, chronic low-grade inflammation contributes to the development of many chronic diseases. Therefore, maintaining the right balance of pro- and anti-inflammatory markers is crucial to a healthy inflammatory response.
This relationship between inflammatory proteins is wonderfully observed during sauna use, where due to an elevation in core body temperature, a pro-inflammatory cytokine interleukin-6 (IL-6) increases acutely. However, elevated IL-6 activates interleukin-10 (IL-10), a potent anti-inflammatory cytokine, which works to help to decrease inflammation (4). Another pro-inflammatory protein, C-reactive protein (CRP) has also been shown to respond to sauna use, with lower levels of CRP linked to greater frequency of sauna use.
So while inflammation may increase during the sauna, there’s strong evidence to suggest that frequent sauna use over the long term can help support a healthy inflammatory response.
Improves depression symptoms
Ripping this quote straight from the research paper; “Chronic activation of the body's inflammatory response system promotes the development of depressive symptoms and induces changes in brain and neuroendocrine function, suggesting that strategies that induce anti-inflammatory pathways may reduce symptoms of depression.” (4) Interestingly, low BDNF levels have also been well established as a contributing factor to depression (7).
As shown earlier, heat exposure helps to lower inflammation and raise BDNF levels, potentially explaining the results of two studies, one over 4 weeks (9), the other just a single session (10), which saw participants experience reduced symptoms of depression (Note: both these studies have limitations, so caution is advised).
Another interesting outtake from the single-session study was their hypothesis that heat stimulates the skin to activate serotonin production in the brain, that is “heat makes the brain feel happy” (10). I went down a bit of a rabbit hole here and found ties to research from the 1980’s to 2021 exploring the association between abnormal thermoregulation and depression. Unfortunately, I know my limitations in digesting papers, so I’m not able to provide further helpful insight :-)
Improves exercise performance & recovery
I want to focus on three things here; increasing human growth hormone, improved performance and better recovery. (I’m sneaking in 3 benefits into one dot point for you!)
Increasing human growth hormone
This one is interesting! Growth hormone plays a key role in stimulating muscle growth, strengthening bones, repairing tissue, and increasing metabolism. A 1986 Finnish study found that sauna use could increase growth hormone a massive 16 fold. However rather than heat acclimation, the study found that intense, infrequent sauna use was required (11). The Huberman Lab explains a protocol to help you replicate this study.
Improving exercise performance
When we exercise our core body temperature increases, accelerating how quickly we reach exhaustion. Sauna use helps the body acclimate to both hot environments and internal heat stress, reducing the impact an elevated core temperature has on performance. Heat acclimation triggers sweating at a lower core temperature, for a longer period, while also reducing cardiovascular strain and lowering heart rate. One study encompassing very high temperature 30-minute sauna sessions, 3 times per week for 3 weeks, saw users' heart rate decrease 11 beats/min; skin temperature decrease 0.8 °C; and peak internal temperature decrease 0.2 °C (4).
Better exercise recovery
Sauna heat increases blood flow to peripheral muscles, helping to speed up the body’s natural healing process. The heat can also make muscles more pliable and elastic, helping to release any tension and alleviate muscle soreness after a workout.
Lastly, as part of the body’s heat defence response, the opioid dynorphin is released (likely why we feel discomfort during heat exposure). However, as dynorphin binds to its relevant receptors (kappa-opioid), beta-endorphin binding receptors (mu-opioid), become more sensitive, at the same time as beta-endorphin levels increase (12). All this helps to suppress the release of pain-promoting substances in the brain, likely a welcome reaction following a hard workout.
Better Sleep Quality
Our core body temperature fluctuates between 36.5 to 37.5°C over the course of the day, following our circadian rhythm; warming us up to start the day and cooling us down just before sleep. This cooling effect signals to the brain that it is time to produce melatonin which is what makes us sleepy.
Using a sauna in the evening (or even a hot shower), ideally 1-2 hours before bed, can help your sleep as the body’s post-sauna response is to cool, lowering our core temperature, stimulating the production of melatonin.
Additionally, heat therapy before bedtime can also help you relax, both physically and mentally, by stimulating muscle relaxation and reducing tension in the body, important elements in falling asleep more easily and enjoying a deeper sleep.
Detoxifies the body
Note: I’ve deliberately put this low down on the list as in my opinion these benefits are often overstated or completely misrepresented. Why? The two primary organs responsible for detoxifying our system are the liver and kidneys, while the main job of sweat is to keep us cool, although yes, many toxic elements appear to be preferentially excreted through sweat (13).
Case in point with my hesitation around the detox benefit is this claim that some infrared sauna companies like to throw around; “Sweat induced from an infrared heat source is comprised of 20 percent toxins whereas sweat induced from traditional heating systems is comprised of 3 percent toxins. This is why it’s accurate to say infrared is 7x more detoxifying than traditional heat.” Let me be clear, this claim is absolutely b*llsh*t. Why? If you go down the rabbit hole in this Atlantic article you’ll see the journalist interviews the textbook author this quote allegedly comes from… who replied with “I have no idea what those citing our textbook would be referencing.”
Ignoring that unfounded claim, let’s take a look at the detox benefits.
Over time, harmful chemicals and heavy metals bioaccumulate in our muscles, fat and organs, which can potentially lead to an array of health issues affecting areas including cognitive function, immune system and metabolic health. As our core temperature increases (through sauna or exercise), our pores open and we sweat. Although sweat 99% is water, sweating has also been shown to facilitate the excretion of certain pesticides and chemicals (including BPAs and phthalates), along with a higher excretion of some heavy metals including aluminium, cadmium, cobalt and lead, compared to elimination via urine (4).
Within the infrared sauna community there is a claim that as it penetrates deeper into the body’s tissues, into our subcutaneous fat, that it has a ‘better’ detox effect, but as yet I’ve not come across anything to support that claim.
Summary
Although there are different ways to heat the body - dry and wet sauna vs infrared sauna - they all increase your core temperature and trigger responses that lead to the incredible benefits we’ve covered.
One last important thing to mention is that we’re all humans, but we’re all unique. While we share mechanistic similarities (e.g. heat exposure increases our heart rate and makes us sweat), the impact and influence of those mechanisms will be different due to differences between each of us.
While I’ve done my best to compile this list of sauna benefits I believe everyone can experience, it’s impossible to take our unique variations into account. Despite that, I strongly encourage you to try sauna therapy for yourself and see how it helps you.
Lastly, if you're ready to start a sauna practice, read what the best type of sauna for you is in this article.
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
https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2130724
https://link.springer.com/referenceworkentry/10.1007/978-1-4419-1005-9_328
https://www.sciencedirect.com/science/article/pii/S0531556521002916
https://www.thorne.com/take-5-daily/article/what-is-bdnf-and-how-does-it-affect-brain-health
https://jamanetwork.com/journals/jamapsychiatry/article-abstract/2521478
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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.
