The Science Behind Tulē’s Thermal Circuit in Davis, CA

Scenes of floatation therapy, sauna, and water bathing as experienced in the thermal circuit at Tulē - An Urban Wellness Retreat.

Modern wellness seekers in Yolo County aren’t just looking for any sauna in Davis, or a cold plunge near Sacramento—they want an experience that feels rooted in tradition yet also informed by modern science. Tulē’s signature thermal spa circuit pays homage to ancient bathing cultures while drawing on contemporary research from experts such as neuroscientist Andrew Huberman, longevity physician Peter Attia and the cold‑exposure pioneer Wim Hof. This article expands on the essentials of our thermal journey—hot soak, sauna, cold plunge, steam and salt float—so you know exactly why each step does more for your body than just feel good (and boy, does it feel amazing).

The heart of hydrothermal therapy

Across cultures, people have long used cycles of heat, cold and rest to balance body and mind. Roman thermae, Turkish hammams, Japanese onsens and Nordic saunas all revolve around the same idea—move between hot and cold water, decompress in steam rooms and saunas and then rest and recover before repeating the cycle (tuledavis.com). Today, scientists recognize that this contrast therapy triggers hormetic stress: brief discomfort that activates your body’s own repair mechanisms (hubermanlab.com). Let’s walk through Tulē’s version of this age‑old ritual and unpack the modern research behind it.

1. Hot soak – priming the body for contrast

Your journey begins with a warm embrace. Our design‑forward hot soaking pool (approximately 102–104 °F) envelops you in soothing warm water, easing you into a parasympathetic state. Warm‑water immersion relaxes tight muscles and encourages joint mobility (tuledavis.com). It increases blood flow and primes your body for the temperature fluctuations to come (tuledavis.com).

But hot water immersion isn’t just about relaxation, a long‑term Japanese cohort study of more than 30,000 people (followed for 19 years) found that individuals who bathed in hot water almost daily had a 35% lower hazard of developing Cardiovascular Disease when compared with those bathing two or fewer times per week. Think of your hot soak as a potential heart-healthy moment of calm to warm‑up for deeper work ahead.

2. Sauna – harnessing hormesis for longevity

After the hot soak, you’ll step into our cedar‑lined dry sauna, heated between 150–195 °F. Sauna bathing triggers a hormetic stress response: core body temperature rises and your heart pumps faster, mimicking a cardio workout (frontiersin.org). Neuroscientist Andrew Huberman explains that this heat stress stimulates the FOXO3 gene, boosting production of heat‑shock proteins that repair damaged proteins and protect against oxidative stress (hubermanlab.com). Regular sauna use (4–7 sessions per week, 5–20 minutes each) was linked to a relative risk reduction of 40% in all‑cause mortality and a significant drop in cardiovascular events in a 2015 JAMA study cited by longevity expert Peter Attia (JAMA). Attia suggests a minimum‑effective‑dose protocol consisting of four 20‑minute sessions weekly at 175 °F (honehealth.com). The detoxifying sweat you feel isn’t just pleasant—it’s part of a physiological cascade that improves circulation, supports heart health, releases endorphins and enhances recovery (tuledavis.com).

Sauna tip: Begin with shorter sessions if you’re new to heat. Stay hydrated and listen to your body. Our sauna in Davis is designed for comfort, with smooth cedar benches and ambient lighting so you can sink deeper into the experience.

See what made Dr. Peter Attia change his stance on Sauna’s during Tim Ferriss’ podcast! Click below or use this link.

Dr. Peter Attia describes what made him change his stance on sauna’s during Tim Ferriss’ podcast.

3. Cold plunge – awakening mind and metabolism

Once you’ve warmed up, it’s time to cool down. Our cold plunge pools (50–55 °F) deliver a rush of stimulation and clarity. Cold exposure is a form of hormesis—brief discomfort that triggers a positive adaptation. Huberman notes that immersion at these temperatures leads to spikes in norepinephrine and dopamine, neurotransmitters associated with mood and focus (hubermanlab.com). Just 11 minutes of cumulative cold exposure per week can convert white fat into metabolically active brown fat, improving insulin sensitivity and cardiovascular health (hubermanlab.com). In a 2025 University of Ottawa study, seven consecutive days of cold‑water immersion significantly enhanced cellular autophagy—the cell’s recycling system—improving resilience and potentially slowing aging (sciencedaily.comsciencedaily.com). A separate 2025 meta‑analysis found that cold‑water immersion may lower stress levels for up to 12 hours and temporarily improve sleep quality, although long‑term effects remain uncertain (sciencedaily.com).

The cold plunge also trains mental grit. Huberman teaches that staying calm during discomfort strengthens the prefrontal cortex’s control over stress responses (hubermanlab.com). But safety is key: begin with 10–30 seconds and work up to a few minutes. Our plunge pools are kept at a safe temperature range, and staff are always nearby (tuledavis.com). Those with cardiovascular conditions should consult a physician before immersing.

The effect of cold plunging on athletic recovery, muscle building, and performance has been a hot topic recently. Traditionally, hopping in an ice bath post-exercise has been supported as beneficial for those aforementioned goals. More recently, we have learned that the outcomes of cold water immersion for athletic and fitness goals may be more nuanced. Likely sparked by recent studies such as this recent study in the European Journal of Sports Science that found that cold water immersion following resistance exercise likely reduces the effectiveness of resistance training on muscle building when compared to no cold water immersion. Although it is important to note that this doesn’t mean that cold plunging prevents muscle building altogether, and, as usual, more studies are needed on this topic. A 2022 Meta Analysis however, indicates positive impacts from cold plunging on muscle soreness and recovery after high intensity exercise and endurance exercise. So we can see that depending on one’s goals, the timing of cold plunging may play a role.

Cold plunge tip: If your goals are to reduce muscle soreness and prepare for another strenuous workout, cold plunging after a workout is a great solution. If your goal is to specifically increase muscle mass and hypertrophy, then wait 4-6 hours post workout to cold plunge. Or simply plunge before your workout, for a great, natural pre-workout routine! Our gym and thermal circuit in Davis provide a great opportunity to maximize your performance goals!

4. Steam – breathing easier and letting go

Step into our infused steam room and feel your body soften as the warm mist surrounds you. Steam bathing has deep roots in Roman, Turkish, and Middle Eastern cultures, where it has long been used as a ritual of cleansing and renewal (tuledavis.com). The moist heat helps open pores, hydrate skin, and may ease congestion, making it a favorite for respiratory relief (tuledavis.com).

Although steam has been researched less extensively than sauna, emerging studies are promising. For example, a 2024 study found that herbal steam baths improved overall quality of life, enhanced sleep, and reduced emotional distress in post-COVID-19 patients.

Many of our guests choose to include steam therapy in their circuit for its soothing combination of warmth and aromatherapy—an invitation to exhale, unwind, and let go.

5. Salt float – weightlessness and stillness

Your journey concludes in our epsom salt float pool—a tranquil reset before beginning the circuit again. The water is kept at skin temperature (around 93.5 °F), creating a neutral reprieve from the extremes of heat and cold. As you float effortlessly, the high concentration of magnesium sulfate produces a sensation of zero gravity, much like the Dead Sea, sweeping you into a state of pure weightless bliss.

But what about the health benefits? For centuries, epsom salt baths have been used anecdotally for muscle recovery, pain relief, and stress reduction. While research suggests the skin is unlikely to absorb significant amounts of magnesium, the therapeutic benefits of floatation come from the unique weightless environment itself.

In fact, one study found that participants who completed 12 floatation sessions over seven weeks experienced significant reductions in anxiety, stress, and depression. Another study explored how the altered state of consciousness and reduced perception of body boundaries may contribute to floatation’s calming, anxiolytic effects.

Unlike traditional float tanks, our communal salt pool is open and spacious—perfect for those who experience claustrophobia or discomfort in enclosed pods. While this may lessen the level of sensory deprivation for those seeking total isolation, it creates a more welcoming and accessible float experience for everyone.

Why We Created the Thermal Circuit at Tulē

At Tulē, our thermal circuit is more than a collection of hot and cold amenities—it’s a carefully designed journey that blends ancient healing traditions with modern wellness science. From the invigorating cold plunge to the restorative sauna and steam room, every step of the circuit is meant to recharge the body, calm the mind, and inspire a deeper connection to personal health.

We saw that Davis, California was missing not just a spa, but a true communal wellness experience. That’s why we created a space where people can gather, unplug, and feel fully alive. The thermal circuit is designed to encourage mindfulness, improve circulation, reduce stress, and spark joy—all while honoring the timeless practice of alternating hot and cold therapy.

By bringing this level of intentional design to our wellness retreat, Tulē invites the Davis community to discover how daily rituals of heat, cold, and rest can become powerful tools for long-term vitality.

Experience it yourself

If you live in Davis, Yolo County, the Sacramento Valley, or anywhere in Northern California, we invite you with open arms to come experience our space. Whether you’re an athlete looking for recovery, a stressed student seeking a reset or simply curious about the health benefits of contrast therapy, a day pass is a perfect way to explore the benefits that Tulē has to offer. Come ready to disconnect from devices, reconnect with your senses and maybe even strike up a conversation with someone new in the lounge.