Video·3 min read·May 2026

Harnessing Heat and Cold: The Science Behind Waon Therapy for Heart Health

Sauna • 3 min read • Based on research by Takahiro Nakagami, Kazuhiro Shimizu, Keiichi Hirano, Hajime Kiyokawa, Masahiro Iwakawa, Yuki Ikeda, Takashi Akiba, Keiichiro Terayama, Akihiro Ogawa, Kohji Shirai (2022)

In our pursuit of wellness, we often seek methods that can enhance our vitality and resilience. If you've ever experienced the soothing warmth of a sauna or the refreshing shock of cold exposure, you may have felt the immediate benefits. But what if these rituals could also play a role in managing serious health conditions, such as heart failure?

A recent study brings new insights into Waon therapy—a thermal treatment that combines sauna use with subsequent rest. This research highlights how this method may improve heart health by addressing arterial stiffness, a critical factor in cardiovascular function.

Understanding Waon Therapy

Waon therapy involves a specific sauna protocol where participants are exposed to a dry sauna at a moderate temperature of 60°C for 15 minutes, followed by a 30-minute rest in a warm blanket. This gentle warming process is designed to enhance circulation and promote relaxation.

In a study involving 21 patients with chronic heart failure (CHF), researchers examined the effects of Waon therapy on a measurement called the cardio-ankle vascular index (CAVI). CAVI is a key indicator of arterial stiffness, which can impact heart health significantly. The findings revealed that patients who responded positively to Waon therapy showed a notable decrease in CAVI levels—indicating improved arterial flexibility—while those who did not respond experienced no change.

The Connection to Heart Health

Why is arterial stiffness important? When arteries become stiff, the heart must work harder to pump blood, which can lead to increased strain and potential complications. In this study, the responders—those who experienced a decrease in CAVI—also demonstrated improvements in their plasma brain natriuretic peptide (BNP) levels, a marker used to evaluate heart function.

Moreover, the study highlighted a concerning trend: patients who did not respond to Waon therapy had a significantly higher rate of rehospitalization or cardiac death within a year. This suggests that monitoring CAVI could help identify which patients might benefit most from Waon therapy, providing a clearer path towards effective heart health management.

Practical Implications for Your Wellness Rituals

Integrating Waon therapy into your wellness routine could offer benefits beyond relaxation. For individuals at risk of or managing chronic heart conditions, this noninvasive treatment might serve as a complementary approach to standard medical therapies. The study suggests that individuals experiencing heart failure symptoms might find value in incorporating regular sauna sessions into their recovery protocol.

As we explore the balance of heat and cold in our wellness practices, it becomes clear that these rituals can be more than just rejuvenating—they can be transformative tools for enhancing our overall health and longevity.

Key Takeaways

Waon therapy combines sauna use with rest, potentially improving arterial stiffness—a key factor in heart health.
Monitoring the cardio-ankle vascular index (CAVI) can help identify patients likely to benefit from Waon therapy.
Incorporating sauna sessions into your wellness routine may support heart health, particularly for those managing chronic conditions.

Based on: Cardio-Ankle Vascular Index Reflects the Efficacy of Waon Therapy in Heart Failure Patients
Takahiro Nakagami, Kazuhiro Shimizu, Keiichi Hirano, Hajime Kiyokawa, Masahiro Iwakawa, Yuki Ikeda, Takashi Akiba, Keiichiro Terayama, Akihiro Ogawa, Kohji Shirai (2022). International Heart Journal

Contrast Collective • Science-backed wellness

Wim's Wise Words

A second take, from someone who's lived it.

🧊 Wim's Wise Words

Cardio-Ankle Vascular Index Reflects the Efficacy of Waon Therapy in

What This Paper Is Actually Arguing

Most of the sauna research we talk about is preventive. Healthy people, long-term habits, population-level risk reduction. This paper is asking a different question: for people who already have chronic heart failure—people for whom standard treatment isn't enough—can heat therapy help? And more importantly, can we predict in advance who will actually respond to it?

The answer to the second question appears to be yes. The cardio-ankle vascular index, CAVI, measures arterial stiffness across the entire arterial tree from the aorta down to the ankle. It's pressure-independent, which makes it a cleaner signal than many cardiovascular markers. In the patients who responded to Waon therapy—their CAVI dropped meaningfully, from roughly 10.3 down to 9.6. In those who didn't respond, CAVI barely moved. Same therapy. Very different outcomes at the cellular level.

How This Connects to the Broader Picture

The Finnish Kuopio data—nearly 1,700 people tracked over years—showed that habitual sauna use at 80 to 100 degrees Celsius was associated with significantly lower cardiovascular mortality. What's striking here is that Waon therapy operates at just 60 degrees. A much gentler heat. And it's still producing measurable improvements in a population of seriously ill patients who weren't responding to diuretics, beta-blockers, or ACE inhibitors.

This aligns with what Rhonda Patrick has emphasized: the cardiovascular benefits of heat aren't primarily about intensity. They're about the physiological cascade—vasodilation, improved blood flow, reduced peripheral resistance, changes in plasma volume. Your heart works less hard when your arteries are more elastic. That's exactly what a dropping CAVI score tells you: the arterial tree has become more compliant. The afterload on the left ventricle has decreased.

The body's ability to tolerate heat stress may be as diagnostically meaningful as the therapy's outcome. When you can't handle warmth, something deeper is failing.

Where There's Nuance

The researchers are careful not to overstate their findings. This is 21 patients, retrospective, at a single center. The multicenter randomized trial they reference actually didn't find statistically significant differences in BNP between Waon therapy and control groups—a humbling caveat. What this smaller study adds is the biomarker lens: CAVI may explain why the multicenter results were mixed. Aggregate data hides responders and nonresponders. When you separate them, the signal becomes clear.

The Practical Take

For most people reading this, chronic heart failure isn't the context. But there's a principle worth holding: not everyone responds to thermal stress the same way, and CAVI testing—increasingly available at cardiology practices—could become a meaningful tool for tailoring heat therapy protocols. If you're supporting someone managing a serious cardiac condition and exploring complementary approaches, this is the kind of biomarker conversation worth having with their cardiologist.

The Detail That Stays With Me

Three patients who requested early discontinuation of Waon therapy due to discomfort—all three died of heart failure within one month. That's not a statistical trend. That's a signal. The body's inability to tolerate even gentle heat may itself be a prognostic marker—a sign that the cardiovascular system has lost its adaptive capacity entirely. Thermal stress reveals what's left. In the knowledge base, we talk often about hormesis: the idea that a controlled stressor builds resilience. This paper shows the inverse is also true. When there's no resilience left to build on, the stressor has nothing to work with. It's a sobering reminder that these protocols aren't magic—they're conversations with biology, and biology has the final word.

Cardio-Ankle Vascular Index Reflects the Efficacy of Waon Therapy in Heart Failure Patients

Harnessing Heat and Cold: The Science Behind Waon Therapy for Heart Health

Understanding Waon Therapy

The Connection to Heart Health

Practical Implications for Your Wellness Rituals

Key Takeaways

Related articles

Waon Therapy for Cardiovascular Disease Innovative Therapy for the 21st

Waon Therapy Improves Quality of Life as Well as Cardiac Function and Exercise Capacity in Patients With Chronic Heart Failure

Preliminary Trial of Lower Leg Thermal Therapy for Patients with Terminal Heart Failure Fitted with Left Ventricular Assist Device