n this live panel from Sauna Days 2025, Glenn welcomes two of the most thoughtful voices in sauna research, Dr. Ashley Mason of UCSF and Earric Lee of the Montreal Heart Institute, for a candid conversation about the current state of sauna science, where the evidence is strong, where it is still emerging, and why integrity matters when talking about health benefits in the sauna world.
This episode goes far beyond the usual wellness headlines. Ashley and Earric dig into the real responsibility that comes with promoting sauna for health, especially in a moment when many businesses lean on scientific claims to sell sauna experiences, home builds, and products. Rather than oversimplifying the message, this discussion brings nuance, humility, and rigor to the bench.
Earric shares insights from two major projects: a cardiac rehabilitation study exploring whether regular sauna bathing can improve outcomes for patients with coronary artery disease, and a sweeping review of roughly 80 years of heat-therapy research, covering everything from traditional sauna and infrared sauna to hot water immersion and foot baths. One of the big takeaways: despite all the enthusiasm around sauna today, the actual number of long-term published studies is still surprisingly limited, and the field has a lot of room to grow.
Ashley brings the mental health lens, drawing from her work on depression, insomnia, and body-based therapies that do not rely on drugs. She explains how heat exposure may relate to thermoregulation, serotonin pathways, and mood improvement, and describes the striking relationship between body temperature and depression. In her research, some people with depression appear to run "hot," not because of fever, but because their bodies do not cool as effectively. That opens a fascinating question: can changing body temperature help change mental state?
Together, Glenn, Ashley, and Earric explore the difference between clinical research and practical sauna use. They talk about why researchers sometimes use intense protocols that are not meant to be copied at home, how long heat exposure may matter more than many people realize, and why dosage, frequency, and total heat load are still not well defined. The conversation also touches on the challenge of translating laboratory findings into real-world sauna practice, especially for people seeking guidance they can actually use.
A major thread throughout the panel is the distinction between traditional sauna and infrared sauna. Earric shares data from the literature showing a fairly even split in long-term published work between the two, while also noting that many infrared studies come from the same Japanese "Waon therapy" tradition. Ashley explains why her own clinical work uses controlled infrared whole-body heating: not because it is culturally superior, but because it allows researchers to isolate heat as a variable and reliably elevate core temperature over time.
The panel also gets refreshingly honest about what remains uncertain. Can a traditional sauna session raise core temperature to the same levels used in clinical depression studies? Maybe, but probably not easily. Is cold plunging necessary? Not necessarily. Does contrast therapy add something meaningful beyond helping people stay in the heat longer? The science is still catching up. Are there clear protocols for children, older adults, athletes, or people with type 1 diabetes? Not yet, at least not with the level of certainty most people would hope for.
There is also a strong practical thread in this episode. Earric encourages sauna bathers to keep a sauna log, much like an exercise log, tracking time, temperature, frequency, and personal response. The idea is simple but powerful: if sauna is a stressor that leads to adaptation, then paying attention to your individual dose matters. Ashley adds an important layer to that idea by reminding listeners that human beings are not static. Age, fitness, depression, stress, sleep, and general health all influence how the body handles heat.
Audience questions help widen the discussion even further. The panel touches on core temperature versus skin temperature, wearable technology, the limits of common thermometers, the role of sweating and blood redistribution, how cold exposure may or may not complement sauna, the possibility that some sauna benefits come not just from heat but from social connection, rest, hydration, and ritual, and why future research needs better control groups to separate these effects.
What emerges is a thoughtful, grounded, and deeply useful conversation: sauna science without the chest-thumping, without the overclaiming, and without losing the wonder. This episode is for sauna builders, bathers, researchers, health professionals, and anyone who wants a clearer picture of what heat can do for the human body and mind, and what questions still deserve honest study.
In this episode: Dr. Ashley Mason and Earric Lee discuss the current state of sauna research, long-term heat therapy studies, traditional sauna versus infrared sauna, depression and thermoregulation, cardiac rehab, body temperature tracking, dosage and duration, cold exposure, aging, children and heat, diabetes considerations, and why the future of sauna science depends on asking better questions with more rigor.
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