Walk into a modern fitness club and you will likely find members who skip the treadmill entirely in favor of the sauna. While some might assume they are simply avoiding a workout, a growing body of research suggests that sauna use alone offers profound health advantages. In Japan—a nation renowned for its longevity and deep-rooted bathing culture—the link between heat therapy and wellness is well-established. Now, international medical journals are shedding light on how these sessions support everything from heart health to mental clarity.
The Rise of the "Totonou" State
As reported by NPR, saunas are driving a major wellness trend in the United States, particularly among a new generation of enthusiasts. Cities like New York and Minneapolis now host regular sauna festivals, and Seattle recently launched its own outdoor sauna village at the National Nordic Museum.
Central to this trend is the pursuit of "totonou(整う)"—a Japanese term meaning "to be in harmony" or "properly set." This state, often described as a "sauna high," occurs after cycling through a sauna, a cold plunge, and a period of rest.
A 2023 study published in PLOS ONE by researchers at Vie Style titled "A study on neural changes induced by sauna bathing: Neural basis of the 'totonou' state" examined this phenomenon through brainwave measurement. The findings suggested that the brain reaches a more efficient state post-sauna; participants showed significantly improved task completion times, indicating that the three-step routine helps regulate brainwaves for optimal performance.
Cardiovascular Benefits Comparable to Light Jogging
The physiological effects of sauna heat are immediate and measurable. Dr. Christopher Minson, a human physiologist at the University of Oregon, notes that saunas stimulate the cardiovascular system in a way strikingly similar to physical exercise. As temperatures rise, blood vessels dilate and heart rate increases to cool the body.
Dr. Sascha Ketelhut, an exercise scientist at the University of Bern, confirms that a traditional Finnish sauna (80–93°C) triggers an acute stress response. This activates the sympathetic nervous system—the "fight-or-flight" response—much like a light jog. Over time, this cycle of activation and recovery improves cardiovascular indicators. Dr. Setor Kunutsor, a cardiologist at the University of Manitoba, suggests that using a sauna at least three to four times per week for 15 minutes per session provides optimal benefits.
Reducing the Risk of Dementia and Respiratory Disease
The long-term benefits of frequent sauna use are equally compelling:
Dementia and Alzheimer’s: A landmark 2017 study published in Age and Ageing followed Finnish men for over 20 years. It found that those using a sauna 4–7 times per week had a 0.34 risk of dementia compared to those who used it only once a week—a staggering 66% reduction in risk.
Respiratory Health: Research from the University of Bristol and the University of Eastern Finland indicates that increased sauna frequency correlates with lower incidences of asthma, pneumonia, and chronic obstructive pulmonary disease (COPD). Frequent users (4+ times per week) saw a 37% lower risk of pneumonia compared to occasional users.
Potential Antidepressant Effects
Heat therapy may also serve as a tool for mental health. Dr. Charles Raison, a professor at the University of Wisconsin–Madison, explains that the pathways the brain uses to regulate temperature overlap significantly with those responsible for mood and emotional states.
A 2016 randomized controlled trial showed that even a single session of whole-body hyperthermia could significantly reduce symptoms of depression. Researchers hypothesize that the sharp rise in interleukin-6 (IL-6) during heat exposure activates the body’s defense and regulatory mechanisms, potentially lifting mood.
