13. Sauna and Brain Health: How Heat Supports Mental Well-Being

Sauna therapy offers profound benefits for the brain and mental health, which are closely intertwined with cardiovascular well-being. Scientific research reveals that many risk factors for heart disease, such as high blood pressure, inflammation, and obesity, also contribute to cognitive decline, dementia, and mental disorders like depression. Regular sauna use has been linked to a lower risk of stroke, Alzheimer's disease, and other neurodegenerative conditions, likely due to improved circulation, reduced inflammation, and the stimulation of heat shock proteins. Additionally, sauna bathing may help alleviate depression by modulating neurotransmitters, reducing stress hormones, and enhancing brain plasticity. With growing evidence supporting its neuroprotective effects, heat therapy emerges as a promising tool for fostering long-term mental resilience and cognitive health.

Defining Optimal Brain and Mental Health

Growing evidence suggests that sauna heat can have a significant beneficial effect on both brain and mental health. But before exploring these effects, it's essential to ask: What does it truly mean to have a healthy brain and a healthy mind?

At first glance, the answers may seem simple—the absence of disease for the brain and perhaps the lack of ignorance for the mind. Yet, in reality, both concepts are far more nuanced and complex.

Defining brain health is so challenging that the two leading organisations in the United States dedicated to this field, the American Heart Association (AHA) and the American Stroke Association, have united to address this question. With the help of a carefully chosen team of top experts, they set out to produce a definitive document outlining what constitutes optimal brain health. [1] They defined it as average performance levels among all people of similar age who are free of known brain or other organ system diseases, in terms of decline from functional levels, or as adequacy to perform all activities the individual wishes to undertake. Brain health is a crucial foundation for a longer, fuller, and more independent life. It enables critical thinking, planned action, and deep emotional connections, all of which shape the daily experiences and progress of individuals.

Their aim was not only to define optimal brain health but also to offer guidelines on maintaining it throughout life. 

You may wonder why a heart association is so invested in brain health. The answer is enlightening: the brain and heart are inextricably linked. Our understanding of the role of cardiovascular risk factors has shown that they are closely associated with cognitive impairment and dementia. In other words, what harms the heart also harms the brain, and vice versa; what benefits the heart also benefits the brain. Numerous studies confirm these closely linked risk factors. [2-6] Conditions such as stroke, dementia, and other cognitive impairments may differ in their manifestations and prognoses. Yet, they share a common enemy: cardiovascular risk factors like blood sugar levels, serum cholesterol, blood pressure, body mass index (BMI), physical activity, diet, and smoking habits. Beyond these shared risk factors, cardiovascular and brain diseases follow common physiological pathways, including inflammation and oxidative stress. [7] Experts even point to direct links between cardiovascular disease and declining cognitive function. [8]  

What about mental health? Defining mental health in a way that applies universally across cultures is as challenging as defining brain health. George E. Vaillant, an American psychiatrist and professor at Harvard Medical School, outlined seven distinct models of positive mental health, each shaped by diverse cultural, philosophical, and scientific viewpoints. [9] These include a Global Assessment of Functioning (GAF) score above 80, multiple human strengths, maturity, positive emotions, socioemotional intelligence, subjective well-being, and resilience to stress. 

Mental well-being is also closely tied to cardiovascular health. [10] The long-held notion that mental disorders are purely the result of defects in neurons and their connections is gradually giving way to a more nuanced understanding. Studies now point to vascular pathologies and disruptions in blood flow as key contributors to conditions such as schizophrenia, autism spectrum disorders (ASD), anxiety, and depression. 

Social Implications of Brain and Mental Disorders

It is vital to point out that the implications of brain disorders extend far beyond individual suffering. The emotional, financial, and societal toll affects patients, their families, communities, and economies. To grasp the magnitude of this crisis, consider that in 2010 alone, the estimated cost of brain disorders in Europe reached a staggering 798 billion euros—a number that has only continued to rise. [11] A healthy brain is, therefore, not just a matter of personal well-being but affects the whole society.

The societal burden of mental health disorders is equally significant. The 2007 Lancet Commission not only assessed the weight of this challenge but also predicted a rapid rise in the number of individuals affected by mental health conditions. [12] The statistics are staggering: nearly one in four people worldwide will experience some form of mental disorder in their lifetime. [13] It's an almost unfathomable figure, yet given the state of global affairs and daily news headlines, it feels both understandable and deeply concerning.

To conclude this sombre realisation, let us remember that the connection between brain health, mental well-being and cardiovascular health is indisputable. Understanding and nurturing this relationship is not merely a matter of science; it is a vital step towards a healthier, more resilient future for us all. Naturally, our common thread here is the sauna. This leads us to an important question: What role does the sauna play in supporting brain health and mental well-being? Or better yet,...

Could Heat Therapy Offer Practical and Effective Support for Brain and Mental Health?

In earlier discussions, we examined how sauna use positively affects key cardiovascular risk factors. Regular sauna sessions have been shown to lower blood pressure and cholesterol levels, reduce inflammation, improve insulin sensitivity, and support a healthier body mass index (BMI). Saunas also replicate some benefits of physical exercise, promoting relaxation, aiding sleep, boosting circulation, increasing oxygen delivery, and stimulating the production of heat shock proteins. In short, saunas are undeniably beneficial for the heart.

Now, let's shift our focus to the brain and mental health. Interestingly, many of the same risk factors that affect cardiovascular health—such as inflammation, poor metabolic function, and high blood pressure—are also strongly linked to cognitive decline and mental health challenges. This raises a compelling question: if sauna bathing supports heart health, could it also be advantageous for the brain and mind?

Emerging scientific research suggests that the answer may be yes. In the following sections, we will examine the evidence linking heat therapy to enhanced cognitive function and improved mental well-being.

Sauna Bathing and Stroke

A stroke can strike at any moment. It is the second leading cause of death globally and the primary cause of disability in adults. Each year, approximately 13.6 million people worldwide experience a stroke, and tragically, more than a third—about 5.5 million—do not survive. [14] Those, however, who do survive often face significant challenges, with varying degrees of disability that can be temporary or permanent.

There are two main types of stroke. The more common ischemic stroke accounts for roughly 90% of all cases. [15] It occurs when blood flow to a part of the brain is reduced or completely blocked, often due to atherosclerosis—a condition typically associated with heart disease but one that affects the entire vascular system, including the brain. When a blood vessel becomes blocked, oxygen and nutrients cannot reach the affected brain tissue. If the blockage persists, brain cells begin to die. [16] Sometimes, these blockages are brief and go unnoticed, yet they still cause small amounts of brain damage. Over time, these so-called silent strokes accumulate, leading to cognitive decline and, ultimately, dementia. [17] The second type of stroke, hemorrhagic stroke, results from bleeding in the brain. [18] This can occur when a weakened blood vessel ruptures, causing blood to pool and exert pressure on the surrounding tissue, potentially leading to severe brain damage, coma, or death. Even in less severe cases, survivors may experience paralysis, numbness, or difficulties with speech and mobility.

Although immediate medical intervention can reduce the risk of death and long-term disability, the most effective approach to stroke is prevention. While one cannot alter certain risk factors such as age, race, and genetic predisposition, others, such as obesity, high blood pressure, high cholesterol, irregular heartbeat, diabetes, smoking, and excessive alcohol consumption, can be managed. [19] Maintaining a healthy diet and engaging in regular physical activity are well-established ways to reduce stroke risk. But what about sauna bathing?

In 2018, the Journal of the American Academy of Neurology published an article titled "Sauna Bathing Reduces the Risk of Stroke in Finnish Men and Women". [20] This international study followed 1,628 middle-aged and older individuals, aged 53 to 74, from eastern Finland over a 15-year period. Researchers tracked their sauna habits and documented stroke occurrences through annual assessments. Participants were divided into three groups: those who used the sauna once a week, those who used it two to three times a week, and those who enjoyed sauna bathing four to seven times a week. The findings were striking—individuals who used the sauna four or more times a week had a 60% lower risk of stroke compared to those who used it just once a week. Even those in the intermediate group, who visited the sauna two to three times weekly, experienced a 14% reduction in stroke risk. The results strongly suggest that sauna use plays a protective role.

Interestingly, when asked why they did not include a group of non-sauna users for comparison, lead researcher Jari Laukkanen explained that so few people in Finland abstain from sauna bathing that any data from such a small group would be unreliable. While this is the first study to directly correlate sauna frequency with stroke risk (to my knowledge), further research would be valuable to confirm these findings. Given the well-documented cardiovascular benefits of sauna bathing, this is hardly surprising. However, what may be even more intriguing is the sauna's potential to positively influence other brain-related conditions, including dementia and Alzheimer's disease.

Sauna Bathing and Dementia / Alzheimer's Disease

"Sauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish men," declared an article published in December 2016 in the journal Age and Ageing. [21] This study explored the link between sauna use and the risk of neurodegenerative diseases. Conducted over two decades as part of the 'Kuopio Ischemic Heart Disease' (KIHD) study, the research followed 2,315 seemingly healthy men aged 42 to 60 years. Participants were categorised into three groups based on their sauna habits: those who used the sauna 4–7 times a week, those who used it 2–3 times a week, and those who used it only once a week. The findings were remarkable—an inverse relationship was observed between sauna frequency and the risk of both dementia and Alzheimer's disease. The more frequently the sauna is used, the lower the likelihood of developing these debilitating conditions. Specifically, among those who used a sauna 4–7 times per week, the risk of any form of dementia dropped by 66%, and the risk of Alzheimer's disease decreased by 65% compared to those who only used a sauna once per week.

Alzheimer's disease, the most common form of dementia [22], affects between 40 and 50 million people worldwide. [23] It is primarily characterised by the loss of protein homeostasis in brain cells and the accumulation of amyloid plaques and neurofibrillary tangles, which result in memory impairment. [24] However, increasing evidence suggests that atherosclerosis of the brain's blood vessels also plays a significant role in the disease. [25] Experts have noted that individuals with Alzheimer's disease tend to exhibit more frequent and severe atherosclerosis in the cerebral blood vessels compared to those experiencing normal ageing or other neurodegenerative diseases. This link appears to be unique to Alzheimer's disease and does not extend to other common neurodegenerative conditions. [26]

A perplexing question remains: why do some individuals develop the hallmark plaques and tangles of Alzheimer's disease but never exhibit cognitive decline? It appears that these pathological changes can occur in the brain without manifesting symptoms if there is no accompanying vascular dysfunction. Another ongoing debate is whether vascular problems precede the disease's pathological process or arise as a consequence of it. [27,28] Many experts argue that controlling cardiovascular risk factors is the most effective way to preserve brain health, even advocating for Alzheimer's disease to be reclassified as a vascular disorder. [29]

Given the sauna's well-documented benefits for cardiovascular health, its role in supporting brain function is hardly surprising. Beyond its impact on the cardiovascular system, saunas also promote the production of heat shock proteins, which are essential for maintaining protein balance within cells. [30] Since the loss of protein homeostasis is a critical feature of Alzheimer's disease, researchers are exploring novel therapeutic strategies centred on stimulating heat shock protein production to combat the neurodegenerative decline. [31] Some even consider developing vaccines based on heat shock proteins. [32] While it remains uncertain whether such therapies will prove effective, one fact is indisputable: heat exposure, whether through hyperthermia, exercise, or sauna bathing, significantly increases the production of these protective proteins. [33]

Furthermore, sauna bathing has been shown to reduce inflammation, a major contributor to brain diseases, including Alzheimer's. Inflammation exacerbates neuronal damage and accelerates cognitive decline. [34] This raises an obvious question—could sauna therapy be an effective treatment for Alzheimer's and even Parkinson's disease? Researchers from Queensland University of Technology in Australia and Brunel University London sought to investigate this very question. [35] In a paper published in January 2020, they reviewed the scientific literature and found no direct clinical evidence confirming sauna therapy as a treatment for Alzheimer's or Parkinson's disease. However, they highlighted epidemiological studies that support the notion and a wealth of indirect evidence suggesting that warming the body through exercise or sauna use can improve neurological health.

A subsequent study, published ten months later, reinforced this perspective. [36] Finnish researchers conducted a large-scale prospective cohort study involving 13,994 men and women aged 30 to 69 years, none of whom had been diagnosed with dementia at the start of the study. Over a 39-year follow-up period, 1,805 participants were diagnosed with dementia. The study revealed a significant reduction in dementia risk among individuals who engaged in sauna bathing 9–12 times per month compared to those who bathed less frequently or not at all. These findings align with the hypothesis that sauna bathing may serve as a protective factor against dementia. While further studies are needed to confirm these benefits, the evidence suggests that regular sauna use may be a powerful tool in safeguarding long-term brain health.

Sauna and Depression

Depression is a shadow that looms over more than 264 million people worldwide, affecting individuals of all ages and walks of life. According to the World Health Organisation (WHO), it is the leading cause of disability and a heavy burden on both financial and social systems. [37] While we have all felt the weight of sadness or an absence of joy at times, true clinical depression is a different beast altogether—one that cannot be fully understood without firsthand experience. Feeling "down" now and then is part of life, a catalyst for growth and wisdom. But when despair lingers, when motivation fades, and when decision-making becomes an insurmountable task, depression reveals itself as a relentless adversary. It takes away joy, cripples confidence, fuels guilt and irritability and makes social interactions seem unbearable. Left unchecked, it can even lead to suicide, the third most common cause of death among young people aged 15 to 29. [38] The very term "depression" originates from the Latin "deprimere"—to press down—a fitting description of its suffocating grip.

Having never personally battled clinical depression (knocking on wood three times as I say this), I immersed myself in research to comprehend its depths. I thought this might enhance my understanding of sauna therapy's potential role in alleviating its symptoms. Among the numerous perspectives I encountered, one particularly compelling definition came from Professor Robert Sapolsky of Stanford University. He described depression as a "biochemical disorder with a genetic component and the influence of early experiences, in which a person does not know how to appreciate sunsets." He seems to have encapsulated the complexity of this enigmatic condition in a single sentence.

Throughout history, humanity's understanding of depression has evolved significantly. Nancy Schimelpfening, in her article on the history of depression [39], explains how ancient Mesopotamians saw it as a spiritual affliction caused by demonic possession, a belief shared by other early civilisations such as the Greeks, Romans, Babylonians, Chinese, and Egyptians. [40] The remedies? Exorcisms, starvation, beatings—harsh and often cruel methods meant to drive out the so-called demons. Thankfully, Greek and Roman physicians had a more enlightened approach, advocating treatments such as exercise, massage, diet, music, baths, and medicinal herbs. [41] Yet, in the Middle Ages, Christianity's influence revived the notion of mental illness as the work of the devil, leading to inhumane treatments. It wasn't until the Age of Enlightenment in the 18th and 19th centuries that depression began to be understood as an inherited temperament flaw—unfortunately, leading to stigma and isolation rather than solutions. By the 20th century, theories on depression diversified, with Sigmund Freud framing it as a response to loss, while behaviourists suggested it was learned, and cognitive theorists pointed to negative thought patterns as the culprit. [42-44]

With modern medicine recognising that depression is not just a disorder of the brain but a systemic disease affecting the entire body, treatment approaches have expanded. Antidepressants targeting neural pathways have had mixed success, sometimes bringing unwelcome side effects. [45] Emerging research suggests that biological factors, including inflammation [46], cardiovascular health [47], microbiota balance [48], hormonal imbalances [49], and stress-related changes in the autonomic nervous system [50], contribute to the development of depression.

Science is starting to recognise the blurring of boundaries between physical and mental health. Treatment for depression increasingly incorporates approaches that heal the body alongside the mind. Anti-inflammatory drugs have shown promise, as has meditation, which alleviates chronic inflammation. [51,52] And among the most intriguing possibilities is whole-body hyperthermia—raising body temperature, as naturally occurs in a sauna.

Though ancient cultures intuitively used heat for mental well-being, modern science is only now catching up. Dr. Charles Raison, an American psychiatrist and author of The New Mind-Body Science of Depression, has been instrumental in exploring hyperthermia's effects. Research suggests that depression is linked to elevated body temperature, inflammation, and impaired thermoregulation, making heat therapy an intriguing avenue. [53] Raison and his team conducted experiments [54] that demonstrated how whole-body hyperthermia produces rapid and lasting relief from depression. Further, a six-week, randomised, double-masked study [55] confirmed that patients who received whole-body heating therapy showed marked improvement compared to those who received a placebo.

Beyond individual studies, large-scale population research from Finland adds weight to the argument. In a 25-year study involving over 2,000 men, those who used the sauna four to seven times a week had a staggering 77% lower risk of developing psychotic disorders compared to once-a-week users [56]. The evidence is compelling, yet the scientific community remains cautious. A 2019 review by Janssen and Hanusch [57] concluded that while hyperthermia appears promising, more studies are needed before it can be formally recommended as a clinical treatment.

Still, with conventional treatments often falling short, why wait? Sauna therapy is a simple, accessible, and low-risk treatment. Notably, sauna use significantly boosts noradrenaline levels [58,59], a neurotransmitter crucial to emotional stability and a key target for antidepressant drugs. [60] It also promotes the release of prolactin, which is vital for neural connectivity. [61] It reduces cortisol, a hormone that, when chronically elevated, can harm memory-related brain structures, such as the hippocampus. [62] Perhaps most strikingly, research indicates that sauna heat stress enhances the expression of brain-derived neurotrophic factor (BDNF) more effectively than exercise alone. [63] Since BDNF is crucial for neuron growth and function, its role in combating depression cannot be overstated. [64]

The benefits of saunas do not end there. Studies have linked sauna use to improved creativity and problem-solving abilities [65], restoration of appetite in mildly depressed patients [66], and even a reduction in depression among cancer patients. [67] With each new study, the conclusion grows stronger: more sauna, less depression. The time has come to embrace an ancient remedy supported by modern science and harness the power of heat to reclaim mental well-being.

Relieving Chronic Tension Headaches with Sauna Therapy

Tension headaches, often dismissed as everyday discomfort, are the most common type, affecting up to 4% of the general population. Women, in particular, experience them more frequently, accounting for up to 65% of cases. [68] The persistent nature of these headaches makes them a frustrating burden, and while a variety of medications exist, their efficacy remains limited. As a result, many seek alternative methods—some turn to coffee enemas, which, while rarely used, are said to be highly effective anecdotally but lack scientific proof. [69] However, a more reliable and scientifically supported remedy comes from the use of saunas. Experts from Southern Cross Hospital, Wellington, New Zealand, conducted a randomised controlled study that confirmed regular sauna bathing significantly alleviates headache pain in individuals suffering from chronic tension headaches. In their findings, they described sauna bathing as a simple yet effective self-treatment with tangible benefits. [70] 

Sauna Therapy for Patients with Severe Motor and Mental Disorders

Beyond headaches, saunas offer another unexpected benefit, particularly for individuals with severe motor and mental disorders. Many patients with neurological conditions such as cerebral palsy experience reduced cardiac output and low heart rate variability. [71] Their limited mobility, often compounded by extended periods in wheelchairs, results in poor muscle activity and compromised blood circulation, leading to persistently cold hands and feet. [72]. Japanese researchers sought to investigate whether sauna therapy could offer relief to these patients. [73] Their comparative study, conducted before and after a single sauna session, revealed striking improvements. Patients' core body temperature increased by 1 degree Celsius, a significant and beneficial change. Heart rates increased while blood pressure saw a slight decrease. More importantly, indicators of peripheral blood circulation—such as skin blood flow, blood flow velocity, pulsatile index, and resistance index—showed remarkable improvement. The study also noted a decrease in numbness and chronic pain in the extremities, with no adverse side effects. These findings suggest that sauna therapy can play a crucial role in enhancing circulation and overall well-being in individuals with cerebral palsy.

A Takeaway Message

While modern science has yet to uncover all the causes of brain and mental disorders, it is widely recognised that the risk factors for brain and mental health issues significantly overlap with those of cardiovascular diseases. Sauna use has been shown to mitigate some of these risk factors. Furthermore, both cardiovascular and neurological conditions share underlying biological stressors such as oxidative stress and systemic inflammation, factors that regular sauna use has been proven to mitigate. While more targeted research would further substantiate these findings, existing evidence, both direct and indirect, strongly supports the notion that sauna therapy exerts a beneficial impact on brain and mental health.