Sweat Your Way to a Longer Life: How Saunas Boost Your Health & Extend Your Lifespan!
Now, science is figuring out how and why saunas have persisted throughout cultures across the world for millennia.
It’s winter — and a great time to think about saunas!
Louise and I have added a sauna, soaker tub, or steam room to every house we’ve purchased since the early 1980s. Back in the 1970s, I’d read an article about how saunas boost the immune system, and ever since then every time I get sick I hop into the sauna or a hot bath. And it works!
Now, science is figuring out how and why this is so successful that it’s persisted throughout cultures across the world for millennia.
Sauna therapy encompasses subjecting the body to heat stress, inducing mild hyperthermia characterized by an elevation in the body’s core temperature. This hyperthermic condition activates various physiological systems aimed at restoring normal body temperature, thus presenting therapeutic advantages.
Central to these advantages lies the principle of hormesis, a biological concept where exposure to a mild stressor, such as heat or extended fasting, triggers a defensive response in the body that surpasses the expected reaction to the stressor.
It is, in other words, abiological response to moderate stress that improves the body's ability to handle more severe challenges. This response initiates a range of protective mechanisms, not only repairing cellular damage but also enhancing resilience against more severe future stressors.
It strengthens you, in other words, particularly your immune system.
Remarkably, the hormetic responses induced by heat stress in sauna therapy closely resemble those activated by exercise, particularly in terms of repairing cellular damage and fortifying the body against stress. This resemblance has even led researchers to explore sauna therapy as a plausible alternative to traditional aerobic exercises, especially for individuals facing challenges in engaging in regular exercise due to chronic diseases or physical limitations.
Furthermore, the stressors induced by sauna therapy intersect with pathways related to the “12 Hallmarks of Aging,” a conceptual framework categorizing biological processes associated with aging. Notably impacted hallmarks include cellular senescence (old cells that have ceased to function but still consume nutrients and energy, causing more rapid aging) and loss of proteostasis, aka the proper folding of proteins.
Unraveling Hormesis and Cellular Senescence
The activation of the body’s intrinsic stress-response systems through hormesis, as triggered by sauna therapy, extends beyond immediate stress coping; it plays a crucial role in reinforcing the body against future challenges, including aspects of aging like cellular senescence.
Cellular senescence, a biological process where cells cease to divide and gradually cease normal functions, contributes significantly to age-related health complications as more cells enter this senescent state with aging. Senescent cells secrete inflammatory markers known as the senescence-associated secretory phenotype (SASP), including pro-inflammatory cytokines, chemokines, and proteases.
The SASP has the potential to exacerbate tissue inflammation, often leading to chronic inflammatory conditions implicated in various age-related diseases. Moreover, these secreted factors can induce senescence in neighboring healthy cells, creating a cascading effect that accelerates tissue aging and dysfunction.
By inducing a mild stress response in a controlled environment, sauna bathing may enhance the body’s resilience to the inflammatory effects and intercellular influences of senescent cells, potentially slowing the aging process and improving overall health. Understanding the molecular mechanisms of heat-induced stress at a cellular level is crucial to comprehend how heat stress induces this resilience.
The Role of Heat Stress and Heat Shock Proteins in Sustaining Proteostasis
As we age, a critical challenge our bodies face is the loss of proteostasis, the delicate balance of synthesizing, folding, and degrading proteins crucial for cellular function. Disruption of this balance with age leads to an accumulation of misfolded or dysfunctional proteins, a hallmark of aging linked to various age-related diseases, including neurodegenerative disorders.
To mitigate protein misfolding and dysfunction, heat stress targets this process by increasing heat shock proteins (HSPs), acting as molecular chaperones ensuring proper protein folding and preventing the aggregation of damaged proteins. In aging, where the cellular machinery for protein maintenance becomes less efficient, HSPs become increasingly vital.
HSPs not only prevent protein disorder and aggregation but also play a crucial role in preventing muscle loss and atrophy. Studies on rodents reveal that local heat application can substantially reduce muscle atrophy during periods of immobilization, highlighting the potential of heat exposure, as experienced in sauna therapy, in preserving muscle strength and integrity — a key factor in healthspan as we age.
Research increasingly indicates a correlation between HSPs and human longevity. A study of Danish nonagenarians (people over 90 years old) suggests that genetic variants influencing the production of stable and functional HSPs may contribute to a longer lifespan. This underscores the potential of increasing HSP levels through practices like sauna therapy.
Regardless of the stress source, though, cells respond to stress, including heat stress in sauna therapy, by increasing HSP expression. Studies show a significant and sustained increase in HSP levels with sauna therapy, indicating its efficacy in stimulating the body's production of protective proteins.
The Impact of Sauna Therapy on Mitochondrial Function and Biogenesis
Studies on sauna therapy demonstrate not only increased HSP levels but also significant improvements in mitochondrial function—a critical aspect of cellular health. These improvements include enhanced mitochondrial biogenesis biomarkers and increased mitochondrial respiratory capacity, crucial measures of metabolic health.
Mitochondria, the cell’s powerhouses, play a vital role in energy production and metabolic processes. Mitochondrial biogenesis, the creation of new mitochondria, is essential for overall healthspan. Healthy mitochondrial function is associated with efficient energy production, improved metabolic health, reduced risk of chronic diseases, and potential impacts on aging and longevity.
Regulating Inflammatory Responses for Enhanced Lifespan: Sauna Therapy's Influence on Immune Balance
Inflammation serves as a vital defense against infections and supports the healing process following injuries, with a robust immune system being pivotal for optimizing lifespan. However, the transformation of inflammation into a chronic low-grade state after the acute phase can pose a dual threat.
Persistent inflammation, often associated with aging, stems from an imbalance in pro-inflammatory and anti-inflammatory factors. The diminishing ability to regulate these factors results in an inflammatory bias, marked by an overly dominant innate immune response, leading to chronic inflammation—a condition increasingly recognized as detrimental to overall health.
At the core of this delicate balance is Interleukin-6 (IL-6), a pro-inflammatory cytokine central to immune response and inflammation regulation. IL-6’s role is intricate: while promoting inflammation, it also activates interleukin-10 (IL-10), a potent anti-inflammatory cytokine. The interplay between these cytokines is crucial for the immune response, with acute elevation of IL-6 proving beneficial, but chronic elevation linked to persistent inflammation and various health issues.
Fascinatingly, activities elevating core body temperature, such as exercise and sauna use, exhibit promising effects on these cytokines.
Several studies indicate acute increases in both IL-6 and IL-10 levels in the plasma following thermal therapies like sauna use. This acute rise holds significance as IL-6 and IL-10 play pivotal roles in the body's immune and inflammatory responses, with the noteworthy increase in IL-10 highlighting its role as a potent anti-inflammatory cytokine.
The ability of sauna therapy to boost IL-10 expression suggests a potential role in modulating inflammatory responses positively. This modulation could have broad implications, especially in managing and mitigating chronic inflammation associated with aging and various chronic diseases.
Sauna Therapy and Cardiovascular Well-being: Mitigating CRP Levels and Inflammatory Risks
C-reactive protein (CRP) is a key player in the body’s acute phase response, swiftly increasing during tissue injury, infection, or inflammation: it’s so clear an indication of problems that your doctor can order a test to determine if your levels are elevated.
While crucial for the immune system’s immediate defense mechanisms, sustained elevated CRP levels pose heightened cardiovascular risks, including atherosclerosis and increased incidence of cardiovascular diseases.
Emerging research suggests that sauna use may effectively reduce blood CRP levels. In a notable study involving over 2000 men in Finland, frequent sauna bathing demonstrated an inverse relationship with CRP levels in a dose-response manner. The more frequently individuals engaged in sauna therapy, the lower their CRP levels tended to be, presenting a potential strategy for reducing inflammatory risks and promoting cardiovascular health.
The implications extend beyond CRP levels, pointing to the broader potential of sauna-induced heat stress in modulating various inflammatory markers. This modulation could contribute to an improved healthspan, reducing the risk of chronic diseases linked to inflammation, particularly cardiovascular diseases.
Sauna Therapy and Heart Health: Parallels with Exercise in Cardiovascular Enhancement
Exposure to heat during sauna bathing elicits physiological responses akin to those observed during exercise, offering notable benefits for cardiovascular health.
Biological responses observed in sauna bathing closely mirror those in exercise.
Moderate-temperature sauna sessions elevate heart rate, comparable to moderate to vigorous physical activity, showcasing similar cardiac responses. Studies measuring the cardiac responses of individuals engaging in both sauna bathing and moderate physical activity demonstrated nearly identical patterns.
When I take a sauna or a long hot bath (both produce the same response) I’ll track my heartbeat rate to roughly measure the elevation of my core temperature. If I can kick it up about 10-20 beats per minute, I know I’ve hit a point where my body is in a “fever” state and is now producing the positive effects of the heat therapy. (Check with your doctor before trying this.)
Regular sauna use, akin to exercise, results in decreased blood pressure, increased heart function, improved blood flow, and enhanced ventilation, contributing to overall cardiovascular well-being. The Kuopio Ischemic Heart Disease (KIHD) Risk Factor study further supports these findings, revealing a reduced risk of cardiovascular disease mortality associated with more frequent sauna bathing.
The effectiveness of sauna bathing is influenced by both duration and frequency. Regular sessions lasting at least 19 minutes have demonstrated significant positive effects, presenting sauna therapy as a non-invasive approach to promote cardiovascular health.
Sauna Therapy as a Non-Invasive Strategy for Improving Lipid Profiles and Reducing Cardiovascular Risk
Dyslipidemia, characterized by abnormal lipid levels in the blood, is a significant predictor of cardiovascular disease risk and the reason millions of Americans are on statin drugs.
Emerging research explores the potential benefits of regular sauna use in positively influencing lipid profiles, offering a non-invasive avenue for enhancing heart health.
Small-scale studies involving healthy adults engaging in sauna sessions demonstrated promising results. Reductions in total plasma cholesterol and low-density lipoprotein (LDL) concentrations were observed, representing positive changes associated with reduced cardiovascular risk.
While these findings are promising, the limitations of small-scale and short-term studies should be acknowledged. Larger, longer-term investigations are necessary to confirm these benefits and comprehensively understand sauna therapy’s role in managing dyslipidemia and reducing cardiovascular risks.
Sauna-Induced Heat Stress and Cognitive Health: Elevating Neurotrophic Factors for Neuroprotection
Cognitive decline associated with aging is linked to neuronal atrophy and inflammation. Elevating neurotrophic factors, crucial for neuronal development and effective communication, presents a potential strategy for neuroprotection.
Sauna therapy, inducing heat stress, has been linked to increased neurotrophic factors, contributing to neurogenesis — the generation of new neurons. Brain-derived neurotrophic factor (BDNF), a key protein influencing neurons, shows elevated levels following heat stress and exercise. Research indicates that increased BDNF levels can have far-reaching neurological benefits, including improved cognitive function and mental well-being.
An insightful study examining the impact of heat stress on BDNF levels revealed a significant increase after a session of hot water immersion. This rise correlated with elevated core body temperature, emphasizing the physiological response to heat stress. The enhanced expression of BDNF holds promise for improving cognitive health, especially in brain regions critical for learning, memory, and executive functions.
The Relationship Between Sauna Usage and Decreased Risk of Neurodegenerative Conditions
A significant observational investigation involving middle-aged Finnish men offers intriguing insights into the association between consistent sauna usage and a lowered risk of developing Alzheimer’s disease.
According to the study, men engaging in sauna sessions 4–7 times weekly displayed a remarkable 65% reduced risk of Alzheimer's compared to those utilizing it only once weekly. This discovery sheds light on potential mechanisms by which frequent sauna use may contribute to the prevention of neurodegenerative diseases.
Maintaining optimal cognitive function relies on sufficient blood flow to the brain and peripheral nervous system. The intricate connection between cardiovascular health and cognitive abilities is well-established, with conditions like hypertension known to alter cerebral blood vessel microarchitecture, potentially impeding cerebral blood flow. This impairment, observed in both mice and humans, is considered a critical concern as poor cerebral blood flow is linked to reduced clearance of amyloid-beta, potentially hastening the progression of Alzheimer’s disease.
Furthermore, sauna-induced heat exposure has been linked to an increased production of Brain-Derived Neurotrophic Factor (BDNF). Elevated BDNF levels could potentially support brain health and cognitive function. Additionally, as highlighted earlier, the rise in heat shock proteins following sauna sessions plays a crucial role in preventing neurodegenerative diseases such as Alzheimer’s.
Sauna Bathing and the Process of Detoxification
In today’s modern environment, we inevitably encounter chemical pollution that can inflict damage on our cells and DNA. Additionally, contemporary lifestyles often lack exposure to natural health-promoting factors such as daily sunlight, consumption of wholesome foods, and maintaining a rhythmic daily routine, all crucial for our well-being. Sauna bathing emerges as an appealing intervention as it effectively facilitates cellular detoxification and regeneration.
As discussed earlier, one of the physiological effects of passive heat exposure during sauna bathing is an increased expression of Heat Shock Proteins (HSPs). These proteins play a crucial role in detoxifying our bodies by eliminating toxic protein aggregates, enhancing tissue oxygenation, improving circulation, and elevating metabolic activity.
Moreover, by raising the body’s core temperature, saunas induce sweat production, akin to the process during exercise. Sweating stands out as one of the most effective ways to rid our bodies of toxins.
Heavy metals such as mercury (Hg), cadmium (Cd), lead (Pb), and chromium (Cr) are often ingested through contaminated food and water. These metals resist decomposition in the body and exhibit high levels of biological toxicity. Sweating, whether through activities like sauna bathing or dynamic exercise, offers a straightforward means of eliminating these heavy metals from our bodies.
In a study involving 12 healthy young university students, participants were either asked to run on a treadmill or sit in a sauna. Sweat samples collected from both groups were analyzed for heavy metals, including nickel (Ni), lead (Pb), copper (Cu), arsenic (As), and mercury (Hg). Both activities, exercise, and sauna bathing resulted in detectable amounts of these heavy metals in sweat, indicating that sauna bathing, much like exercise, can effectively detoxify the body of heavy metals through sweating.
Studies comparing sauna use to exercise have consistently demonstrated that regular sauna bathing promotes the expression of HSPs and sweating, aiding our bodies in eliminating various toxic substances, from misfolded proteins to heavy metals.
The Role of Thermal Stress in Modulating Cortisol and Serotonin Levels for Stress Relief
One of the primary motivations for sauna usage is relaxation and stress relief. Sauna use has consistently been linked to feelings of relaxation and an enhanced sense of well-being. This effect can be attributed to specific hormonal changes induced by sauna bathing, making individuals less susceptible to stress and anxiety.
Cortisol, a key hormone associated with stress, functions as nature’s built-in alarm system. During periods of heightened stress, cortisol levels surge and may interfere with immune, reproductive, digestive, and growth functions. When stress diminishes, cortisol levels naturally decrease. However, consistent exposure to stress can disrupt this natural decline in hormonal levels.
Regular sauna use trains the body to cope more effectively with stressful situations. Each sauna session exposes the body to thermal stress, gradually increasing tolerance.
A study measuring cortisol levels in people unfamiliar with sauna bathing found that while thermal stress from the sauna raised cortisol levels in all participants, those undergoing multiple sessions exhibited a smaller increase compared to those with just one session. This suggests that repeated sauna use conditions the body to manage stress more efficiently by moderating the rise in cortisol levels.
Apart from cortisol, sauna bathing promotes the release of serotonin — which regulates a team of “maintenance workers” in the brain ensuring smooth operations. These workers regulate anxiety, sleep, appetite, and overall emotional well-being.
Insufficient serotonin levels can lead to increased anxiety, sleep disturbances, and other emotional imbalances. Heat exposure during a sauna session prompts the release of serotonin in the brain, ensuring that mental well-being remains stable and positive, alleviating feelings of stress and anxiety.
The bottom line here is that a regular sauna (or hottub, steam-room, or hot bath) can really help maintain your physical and mental health as well as extend your lifespan!