Video·3 min read·May 2026

Harnessing Heat: The Science Behind Sauna and Cold Exposure for Heart Health

Sauna|Mechanisms|Health Benefits • 3 min read • Based on research by Yunuo Su, Adela Martinkova, Emma O’Donnell, Stephen J. Bailey, Christof A. Leicht (2025)

In our fast-paced world, we often seek simplicity in our self-care rituals. What if a sanctuary of warmth could offer us more than just relaxation? Emerging research suggests that heat therapy, particularly through sauna use, can have profound effects on our cardiovascular health.

Understanding the nuances of how heat affects our bodies can empower us to make intentional choices in our wellness journeys. Recent findings reveal that both continuous and intermittent heating can promote heart health, but they do so in different ways. Let’s explore how these practices can enhance our resilience and overall well-being.

Understanding Heat Therapy

Heat therapy, particularly sauna use, is recognized for its ability to improve cardiovascular function. This research examined two methods of passive heating: continuous heating for 60 minutes and intermittent heating, which involved three 20-minute sessions with cooling breaks in between.

Participants experienced significant changes in cardiovascular markers during continuous heating, including increased heart rate, blood pressure, and enhanced blood flow. Specifically, rectal temperature rose by an average of 1.2°C, indicating a strong physiological response. In contrast, intermittent heating led to a smaller temperature increase of just 0.5°C, suggesting a gentler approach while still delivering benefits.

The Gender Factor in Thermal Perception

One compelling aspect of this study is the difference in thermal perception between males and females. Females exhibited higher skin perfusion and plasma nitrite levels, which are indicators of better blood flow and cardiovascular function. However, they also reported greater discomfort during continuous heating, suggesting that while the physiological benefits are significant, the experience can vary greatly based on gender.

This insight emphasizes the importance of tailoring heat therapy protocols. For those seeking a more comfortable experience without sacrificing benefits, intermittent heating may be the ideal choice. It allows for recovery periods, making the ritual more accessible and enjoyable.

The Science-to-Benefit Connection

So, what does all this mean for you? The mechanisms at play during heat therapy involve an increase in plasma nitrite, which helps dilate blood vessels and improve blood flow. This is crucial for cardiovascular health, as it can reduce arterial stiffness and enhance microvascular function.

When you engage in regular sauna sessions or contrast therapy, you are actively working to improve your heart health and resilience. While continuous heating may offer a more intense cardiovascular workout, intermittent sessions can provide a more balanced approach, allowing you to enjoy the ritual without overwhelming discomfort.

Key Takeaways

Consider incorporating intermittent heating into your wellness routine for cardiovascular benefits without discomfort.
Be mindful of individual differences in thermal perception; tailor your heat therapy to suit your experience.
Regular engagement with heat therapy can enhance blood flow and improve heart health, contributing to long-term wellness.

Based on: The acute effects of continuous and intermittent whole-body passive heating on cardiovascular disease risk indicators in healthy and young males and females
Yunuo Su, Adela Martinkova, Emma O’Donnell, Stephen J. Bailey, Christof A. Leicht (2025). European Journal of Applied Physiology

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The acute effects of continuous and intermittent whole-body passive

What This Paper Is Actually Arguing

Here's the question nobody was asking clearly until now: does it matter whether you sit in a sauna for 60 unbroken minutes, or whether you do three 20-minute rounds with cooling breaks in between? We've been comparing "heat therapy" against "no heat therapy" for years. This study finally compares two patterns of heat therapy against each other.

The answer is nuanced. Continuous heating produced larger increases in core temperature, heart rate, systolic blood pressure, plasma nitrite, and IL-6. Intermittent heating produced smaller responses across every marker. But here's the crucial part: intermittent heating was significantly more comfortable, particularly for females, who reported more unfavorable thermal perception during continuous sessions. The physiological signal was smaller, but the experience was dramatically better.

Where This Fits in the Larger Picture

The plasma nitrite finding is worth sitting with. Nitrite is a proxy for nitric oxide — the molecule your endothelium releases to dilate blood vessels and improve blood flow. When heat elevates plasma nitrite, it's driving the same vasodilatory cascade that underlies sauna's effects on arterial stiffness and cardiovascular disease risk. The Hoekstra et al. work, referenced throughout this paper, established that even modest core temperature increases of around 0.6 degrees Celsius can trigger this response. This study confirms it: intermittent heating raised core temperature by only half a degree, yet still moved the plasma nitrite needle.

The IL-6 story is equally interesting. IL-6 gets a bad reputation because it's associated with chronic inflammation. But the acute IL-6 spike from heat is different — it stimulates the production of anti-inflammatory cytokines like IL-1ra and IL-10. You're essentially using a short-term inflammatory signal to prime a longer-term anti-inflammatory response. Continuous heating produced a stronger IL-6 spike, but intermittent heating still triggered the cascade.

Traditional sauna culture figured this out empirically centuries ago. Go in, come out, cool down, go back. This study is science validating what Finnish intuition already knew.

The Sex Difference Nobody Was Measuring

This is where the paper breaks new ground. Females showed higher skin perfusion and higher plasma nitrite concentrations in both conditions — meaning the endothelial response was more pronounced. But they also experienced significantly more discomfort during continuous heating, not intermittent. The researchers controlled for menstrual cycle phase, scheduling sessions in the early follicular phase when estrogen is low, which removes a major confound that plagues most exercise and thermal research involving females.

The implication is practical: females may get a stronger vascular signal from heat therapy while simultaneously finding prolonged continuous sessions less tolerable. Intermittent protocols close that gap. Same cardiovascular benefit territory, much more manageable experience.

What I'd Actually Recommend

If you're new to heat therapy, or if you've ever bailed out of a sauna because it felt overwhelming, intermittent is your entry point. Three rounds of 20 minutes with 15-minute cooling breaks will still move your cardiovascular markers. You don't need to white-knuckle through an hour of continuous heat to get the benefit. And if you're female, the data specifically supports intermittent as your default protocol — same vascular response, without the elevated discomfort profile.

For those already adapted to heat, continuous sessions will drive a stronger acute response. But the honest takeaway from this research is that the dose-response curve isn't about duration alone — it's about the pattern. Intermittent heat, done consistently, is not a compromise. It's a legitimate protocol. One your ancestors in the Finnish sauna tradition were running long before we had a way to measure plasma nitrite.

The acute effects of continuous and intermittent whole-body passive

Harnessing Heat: The Science Behind Sauna and Cold Exposure for Heart Health

Understanding Heat Therapy

The Gender Factor in Thermal Perception

The Science-to-Benefit Connection

Key Takeaways

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