The Science of Sauna: How Heat Supports Hormones and Holistic Wellness
The heat we enjoy in a sauna is more than comfort, it can be a catalyst for deep physiological change.
WORDS Elissa Rose
For centuries, cultures around the world have turned to heat as a source of restoration. The use of saunas is considered to go back 10,000 years, with customs that extend across the globe. However, the act of sitting in warmth has become more than tradition – it’s therapy. Today, saunas are being redefined not only as spaces of relaxation, but as tools for regulating hormones and reducing stress.
With expert insight from Dr. Emilia Vuorisalmi, a physician and hormonal health specialist and Matias Järnefelt, CEO of global sauna brand HARVIA, we examine the physiological mechanisms behind sauna use, the role of heat in modulating hormonal systems and what defines a truly healthy sauna in the modern world.
Swedish studio Sandellsandberg designed Big Branzino, a floating sauna for trips across the Stockholm archipelago. Photo courtesy of Filip Gränström
Understanding Three Main Sauna Types
All saunas are built around the principle of heat exposure, but the way that heat is delivered varies significantly between types:
1. Traditional Finnish Sauna
The Finnish sauna uses dry heat – typically between 158°F and 212°F. Water is often poured onto hot stones to create bursts of steam, a moment called löyly, though the air remains largely dry. This type is known for its intense, immersive heat and is widely celebrated for its robust cardiovascular and muscular benefits.
2. Infrared Sauna
Infrared saunas use radiant heat panels to warm the body directly, rather than heating the air. The temperatures are milder – usually between 104°F and 140°F. Despite the lower temperature, infrared saunas can produce a deep, penetrating warmth and are praised for extended, relaxing sessions that support circulation and muscle recovery.
3. Steam Sauna (Turkish Hammam)
Unlike the dry environments of the other two, steam saunas operate at lower temperatures (around 104°F to 122°F) but at 100 percent humidity. The warm mist softens the skin and opens the respiratory system, making it a favorite in spa settings for both cosmetic and sinus-clearing benefits.
Learn more about global bathing traditions: Sacred Waters
Soria Moria sauna, Norway. Photo courtesy of Maija Astikainen
Hormones in the Heat: How Saunas Affect the Endocrine System
As Dr. Emilia Vuorisalmi explains, regular sauna use has “a deeply regulating effect on the hormonal system, particularly in relation to stress and mood.” Initially, the heat exposure triggers a spike in cortisol – the body's natural stress hormone – but with continued use, sauna practice lowers baseline cortisol levels, helping the body build greater resilience to stress. Vuorisalmi notes, “sauna sessions stimulate the release of endorphins, the body’s natural mood-lifters,” enhancing both emotional wellbeing and physical relaxation.
Each sauna type affects the body slightly differently. “Traditional saunas, with their higher temperatures and dry heat, tend to provoke a stronger initial hormonal response,” she says. Infrared saunas, on the other hand, “gently stimulate similar pathways” with less thermal intensity, while steam saunas “offer similar stress-reducing effects” through warmth and humidity.
Reproductive Health and Hormonal Harmony
Stress hormones, reproductive hormones and mood-regulating neuromodulators are all interconnected – and sauna has the potential to influence this delicate web. Sauna exposure has been shown to temporarily boost growth hormone levels, which aid recovery, metabolism and tissue repair. While long-term impacts on sex hormones are still being explored, Vuorisalmi emphasizes that sauna can “create the internal conditions that support hormonal balance, especially by improving circulation and reducing stress.”
This is particularly important because, as she explains, “sex hormones like estrogen, progesterone and testosterone are synthesized from the same precursor as stress hormones. Chronic stress can redirect resources away from reproductive hormone production. Supporting stress regulation through regular sauna use may therefore indirectly promote a healthier balance in sex hormones.”
Studies also suggest that sauna may increase prolactin – the hormone that supports lactation. In Finland, sauna is even part of the postpartum ritual. “Many mothers use it to help the body recalibrate after birth,” Vuorisalmi says. “For those who are breastfeeding, this can gently support milk production.”
A floating sauna made from recycled shipping containers by Architect Nick Polansky in San Francisco Bay. Photo courtesy of Alex Farnum
From Burnout to Balance: Sauna as a Modern Stress Antidote
The modern world has placed unprecedented strain on our endocrine systems. Long hours, digital saturation and constant stimulation leave many in a chronic state of low-grade stress. “This chronic activation impacts our hormonal systems, depleting energy and increasing reactivity,” Vuorisalmi says. “Sauna offers a natural counterbalance through a process called hormesis – where small, controlled stressors actually make us stronger.”
Vuorisalmi highlights one particularly compelling area of research, in that “chronic stress can shorten telomeres, accelerating aging and increasing disease risk. Sauna use has been linked to reduced oxidative stress and inflammation, which may help protect telomere length and support DNA integrity over time.”
“Whether we’re alone or with others, sauna helps us reconnect with ourselves – and from that place, it’s easier to connect more fully with others.”
Dr. Emilia Vuorisalmi
The “Love Hormones” and Deeper Healing
Beyond stress relief, saunas can also support the neuromodulators that influence our broader hormonal architecture – namely dopamine, serotonin and oxytocin. Vuorisalmi calls them “the love hormones,” explaining that dopamine, the molecule of direction, “helps us reconnect with purpose. In the quiet heat of the sauna, we finally have space to ask: Am I walking the right path?” Serotonin, the molecule of safety, is supported by warmth and ritual, and “saunas have long been emotional refuges. They create a grounded space where the nervous system can soften, rest and reset.” Oxytocin, the molecule of connection, grows when we feel safe. “Whether we’re alone or with others, sauna helps us reconnect with ourselves – and from that place, it’s easier to connect more fully with others.”
A floating Swedish sauna designed by Big Branzino. Photo courtesy of Filip Gränström
What Makes a Healthy Sauna?
From a product perspective, HARVIA CEO Matias Järnefelt sees clear distinctions between sauna types and what people seek. “In our heritage markets in Europe – particularly Finland and Scandinavia – traditional saunas remain the most popular,” he notes. Infrared saunas are on the rise in North America thanks to their convenience and gentler heat, while steam saunas are often preferred in high-end spa settings for skin and respiratory benefits.
Across all markets, however, he sees a common thread, that “people are increasingly seeing the sauna not just as a place to unwind, but as an integral part of a holistic wellness routine.” One misconception he hopes to address is the idea that sweating alone is the mechanism of detox. “Sweat itself is made up mostly of water, salt, small amounts of minerals and only minimal amounts of toxic substances,” he explains. “The true value of sauna lies more in how it activates the circulatory, endocrine and nervous systems.” He also highlights the growing role of sauna in longevity, by saying that “studies by Laukkanen et al. have shown that all-cause mortality decreases among individuals who use a sauna frequently.”
“People are increasingly seeing the sauna not just as a place to unwind, but as an integral part of a holistic wellness routine.”
Matias Järnefelt
Innovation and the Future of Sauna
Järnefelt points to recent advancements that are redefining the sauna experience – from integrated touchscreen controls to streaming apps like Spotify and YouTube for guided wellness sessions. “This kind of seamless content integration turns the sauna into a fully immersive wellness environment,” he says. HARVIA is also prioritizing sustainability. “We’ve introduced the world’s first solar-powered sauna and announced a technology partnership with Toyota to explore the use of hydrogen as a clean, renewable energy source for heating saunas.”
But beyond tech, Järnefelt sees sauna as a much-needed cultural counterbalance. “We are constantly bombarded by notifications, screens and digital noise. Sauna is the antithesis of that environment – it’s quiet, warm and grounding.” He says it's “a ritual of restoration.”
Through reduced cortisol, enhanced mood and hormonal recalibration, sauna becomes more than heat – it becomes healing. As Vuorisalmi reminds us, “in a world that moves fast and demands a lot, sauna offers a rare moment to slow down. The stillness and heat create a space where deep healing can begin.”
 Heit Grimo HARVIA sauna in Norway. Photo courtesy of Opulent Construct by Heit Grimo Sauna |
 HARVIA heater used in this sauna in Norway. Photo courtesy of Wild Sauna Norway |
 The HARVIA Cilindro pillar heater used in this sauna. Photo courtesy of HARVIA |
 This Australian sauna, built by Opulent Construct and featuring a HARVIA heater. Photo courtesy of Opulent Construct |
Feature Image: Maija Astikainen
Photography: Filip Gränström, Maija Astikainen, Alex Farnum
HARVIA Photography:
Opulent Construct by Heit Grimo Sauna
Opulent Construct
