Infrared sauna research
Infrared sauna studies that used Clearlight saunas: what they measured and found
University research teams have used Clearlight saunas as study equipment in five peer-reviewed infrared sauna studies: two with a Sanctuary 2 cabin, at Cardiff Metropolitan University and RMIT University, and three with a Curve dome at the University of California, San Francisco (UCSF). Here is what each study measured, what it found and what it could not show, with its size and design.
Sauna Republic is an authorized Clearlight dealer. Each summary reports what the researchers did and wrote; none is a health claim for any product.
How we chose the studies and how to read them
We began with the studies on Clearlight's research page and searched for other peer-reviewed papers whose methods or abstract name a Clearlight sauna, keeping only papers we could read in full or in abstract. Four of the five name the equipment in the text we reviewed. For UCSF's 2024 study, the abstract does not name the device; Clearlight states it was the Curve dome, and the same team's later papers name that dome. We left out a single-patient case report from the UCSF group, and we found no peer-reviewed Clearlight sauna research from other groups, although our search was not exhaustive.
Lists of infrared sauna research also include studies of traditional saunas, other manufacturers' infrared saunas, cold water and cell cultures. Those did not use Clearlight equipment and are outside this guide's scope. For the wider sauna research, see our infrared sauna benefits guide.
Each paper is linked in the FAQ.
The five studies at a glance
Two of the UCSF studies paired heat sessions with cognitive behavioral therapy (CBT). Temperatures are the settings or targets the researchers reported.
| Study | Journal and year | Clearlight equipment | Who and how many | Design | What it measured | Main finding |
|---|---|---|---|---|---|---|
| Cardiff Metropolitan University | Experimental Physiology, 2026 | Sanctuary 2 at 149°F (65°C) | 12 healthy adults, average age 26 | One 45-minute session, no comparison | Rectal temperature, heart rate, blood pressure, fluid loss, comfort | Rectal temperature up about 2.5°F (1.4°C); heart rate rose to 153 bpm on average; rated "extremely hot" |
| RMIT University | Complementary Therapies in Medicine, 2022 | Sanctuary 2 at 140°F (60°C) | 10 healthy women, average age 36 | Randomized crossover: sauna, cycling and seated rest, 45 minutes each | Ear temperature, breathing rate, blood pressure, arterial stiffness, heart rate variability | Ear temperature highest in the sauna; no significant differences in blood pressure, arterial stiffness or heart rate variability |
| UCSF | International Journal of Hyperthermia, 2021 | Curve Sauna Dome | 25 healthy adults | Single-session feasibility study | Time to reach a core temperature of 101.3°F (38.5°C) | All 25 reached it, in about 82 minutes on average |
| UCSF | International Journal of Hyperthermia, 2024 | Curve dome (identified by Clearlight) | 16 adults with major depressive disorder | Single-arm feasibility study: CBT plus heat, no control group | Heat sessions completed; depression scores | 13 completed at least four heat sessions; scores fell, with no comparison group |
| UCSF | Global Advances in Integrative Medicine and Health, 2025 | Clearlight Curve Sauna Dome | 30 adults with major depressive disorder | Randomized, single-blind pilot: CBT plus heat or CBT plus a low-heat sham | Acceptability; depression scores | Procedures acceptable; scores fell substantially in both groups, at least as much with the sham; groups not compared statistically |
The Cardiff Metropolitan University study: heat strain at 149°F
Published in Experimental Physiology in 2026, this single-arm study had 12 healthy adults (six women and six men, average age 26) sit for 45 minutes in a Clearlight Sanctuary 2, listed in the paper as the "Sanctuary 2 Person Sauna Pro," set to 149°F (65°C). The measured temperature was about 147°F (63.9°C) at 19% relative humidity. Rectal temperature was recorded throughout, and there was no comparison condition. Clearlight supplied the sauna. The researchers reported these average changes:
The authors described "substantial increases in rectal temperature and systemic physiological strain comparable to values previously reported in the passive heating literature," and wrote that how far a far-infrared sauna raises core temperature is "governed by the thermal load imposed."
What the Cardiff study does not show
The RMIT University trial: sauna, cycling and seated rest
Published in Complementary Therapies in Medicine in 2022 by Joy Hussain, Marc Cohen and colleagues (Clearlight lists it as RMIT University research), this randomized crossover trial was run at the Queensland Academy of Sport's indoor research gym in Brisbane and asks in its title whether infrared sauna is "exercise-mimetic." Ten healthy women (average age 36) each completed three 45-minute conditions in random order: seated rest, a Clearlight Sanctuary 2 held at 140°F (60°C) and under 20% relative humidity, and moderate cycling at 55% to 70% of maximum heart rate, each split into three bouts with 5-minute cool-downs. Because every woman did all three, each served as her own control, a design the authors cite as the study's strength. Clearlight and its local distributor loaned the sauna, and the authors report no conflict of interest.
Ear temperature was higher in the sauna than in either comparison, by a mean of about 1.9°F (1.05°C) over rest and 1.4°F (0.79°C) over cycling. Breathing rate rose only with exercise. Blood pressure, arterial stiffness and heart rate variability showed no significant differences among the three conditions. The authors wrote that these findings suggest the sauna's physiological effects are "underpinned by thermoregulatory-induced responses, more so than exercise-mimetic cardiorespiratory or cardiovascular activations": on these measures, more a heat response than an exercise-like one.
What the RMIT trial does not show
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Get PricingThe UCSF whole-body hyperthermia studies in the Curve dome
A UCSF team has used Clearlight's Curve, a one-person far-infrared dome you lie in with your head outside, for whole-body hyperthermia: supervised heating to a set core temperature, which was 101.3°F (38.5°C) in the 2021 and 2025 studies. These were research protocols, not ordinary home sauna sessions.
2021: a Curve sauna dome study in 25 healthy adults
This single-arm feasibility study, published in the International Journal of Hyperthermia, gave 25 healthy adults one session each of up to 110 minutes in the dome, which the abstract names as the Curve Sauna Dome. A session ended once rectally measured core temperature had held at 101.3°F for two consecutive minutes. All 25 reached the target, in about 82 minutes on average (range 61 to 110). Its mood analyses were exploratory, and the change in self-reported depression symptoms was not statistically significant, so the study speaks to the protocol's feasibility, not to any effect on mood.
2024: CBT plus heat in 16 adults with depression
This single-arm, open-label feasibility study, in the same journal, gave 16 adults with major depressive disorder weekly CBT plus heat sessions; the heat schedule was cut midway from eight weekly sessions to four every other week. The abstract does not name the device; Clearlight states it was the Curve dome. The primary outcome was heat sessions completed: 13 participants (81.3%) completed at least four. Among the 12 participants at the final assessment, Beck Depression Inventory (BDI-II) scores fell by an average of 15.8 points, and 11 of those 12 no longer met diagnostic criteria for the disorder. With CBT for everyone and no comparison group, the study cannot show what part, if any, the heat played; the authors cite the small sample and single-arm design as limits and call for larger controlled trials.
2025: a randomized pilot trial with a sham comparison
The largest study here, and the only randomized infrared sauna clinical trial among the five to enroll patients, appeared in Global Advances in Integrative Medicine and Health in 2025. Thirty adults with major depressive disorder all received CBT and were randomly assigned to add four every-other-week sessions of either whole-body hyperthermia in the Clearlight Curve Sauna Dome, to a core temperature of 101.3°F (38.5°C), or a sham of similar length heated to only about 0.2°F (0.1°C) above the starting core temperature. The single-blind, registered trial (NCT05041361) was designed to test acceptability, not effectiveness, and was funded by the National Institutes of Health through its National Center for Complementary and Integrative Health, and by three foundations.
Depression scores fell substantially in both groups. BDI-II scores dropped by an average of 19.07 points in the heat group, where 80.0% no longer met diagnostic criteria, and by 21.10 points in the sham group, where 92.9% no longer met them. The authors did not plan a statistical comparison between the groups. They found the procedures acceptable, wrote that the sham "was not fully credible and may have exerted antidepressant effects," and called for research on whether adding heat to CBT has any additional effect. The trial shows neither that the heat helped nor that it did not.
What these studies add up to
Read together, the papers show that Clearlight equipment can deliver a substantial, controlled heat load for research: the Sanctuary 2 ran at or close to each cabin study's setting, and the Curve brought every volunteer in UCSF's 2021 study to the target core temperature.
They do not establish the health effects of regular sauna use. The largest study enrolled 30 people, three tested single sessions, none studied regular home use, and none compared a Clearlight sauna with a traditional sauna directly. Neither study with a comparison group separated the sauna from the alternatives on health-related measures: RMIT found no significant differences in blood pressure, arterial stiffness or heart rate variability between sauna, cycling and rest, and in UCSF's 2025 trial the sham group improved at least as much as the heat group. Larger controlled trials are still needed, as the UCSF authors say.
What this means if you are buying a sauna
For a buyer, these infrared sauna studies say more about the equipment than about health outcomes. The deciding questions are practical: temperature range, controls, build, spectrum (the Sanctuary adds near- and mid-infrared heaters to far infrared; the Premier is far infrared only) and fit with your room and electrical service. Our Clearlight saunas buying guide and Sanctuary vs Premier guide compare the cabins, and our Curve dome guide covers the lie-down format. Choose a sauna for the heat, fit and build you want, not as medical care.
Research settings are not home routines. Cardiff's young, healthy volunteers rated 45 minutes at 149°F "extremely hot" and "extremely uncomfortable." At home, start with shorter, cooler sessions, follow the manufacturer's guidance, rehydrate afterward (our hydration and electrolytes guide covers a simple routine), leave the heat if you feel dizzy or unwell, and consult a healthcare professional first if you are pregnant, have a heart or blood-pressure condition, or take medication.
For clinics and research teams
The Clearlight models in the published research are the Sanctuary 2, a two-person full-spectrum cabin that needs a dedicated 120V, 20-amp circuit, and the Curve dome, a one-person far-infrared unit that plugs into two standard 120V outlets. The study settings were research protocols, not operating guidelines, so any facility should set its own session limits and supervision. For commercial settings, see our guide to Clearlight Sanctuary saunas for commercial use; research groups can send their requirements through our pricing request form for current specifications and pricing.
Frequently asked questions
Have Clearlight saunas been used in clinical research?
Yes. Five peer-reviewed papers from Cardiff Metropolitan University, RMIT University and UCSF used Clearlight equipment. All were small single-session, feasibility or pilot studies.
Do these studies prove infrared saunas are good for you?
No. They recorded short-term responses to heat, such as higher body temperature and heavy sweating, in groups of 10 to 30 people. The one comparison with exercise found no significant differences in blood pressure, arterial stiffness or heart rate variability, and in the one randomized trial with patients, the sham group improved at least as much as the heat group.
Which Clearlight models were used?
The Sanctuary 2 at Cardiff and RMIT, and the Curve dome at UCSF (identified by Clearlight for the 2024 study). The Cardiff paper describes its cabin as far infrared, while the RMIT paper calls the same model full spectrum; the Sanctuary line pairs far-infrared panels with front-wall heaters that add near and mid infrared. The Curve is far infrared only.
Did Clearlight fund the studies?
The Clearlight support we could confirm was equipment for two studies: Clearlight supplied the Cardiff sauna (the authors received no financial compensation) and, with its local distributor, loaned the RMIT sauna. UCSF's 2025 trial was funded by the National Institutes of Health and three foundations; the paper describes the dome as commercially available, and we found no statement that Clearlight supplied it. We did not review the funding statements of the 2021 and 2024 UCSF papers.
Is the Curve dome the same as a cabin sauna?
No. The Curve is a one-person dome you lie in with your head outside, while the Sanctuary 2 is a seated cabin for two. UCSF used the dome to heat people to a set core temperature under supervision, unlike the timed, fixed-temperature cabin sessions at Cardiff and RMIT, so the results are not directly comparable.
Where can I read the studies?
Cardiff's paper in Experimental Physiology (2026), RMIT's trial in Complementary Therapies in Medicine (2022) and UCSF's randomized pilot in Global Advances in Integrative Medicine and Health (2025) are open access. Abstracts of UCSF's 2021 study and 2024 study in the International Journal of Hyperthermia are available online.
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Clearlight, Sanctuary, Premier and Curve are trademarks of Sauna Works, Inc., dba Clearlight Infrared. Sauna Republic is an authorized Clearlight dealer. This article is for educational purposes and is not medical advice. Clearlight describes its products as general wellness products; their statements have not been evaluated by the FDA, and they are not intended to diagnose, treat, cure or prevent any disease. If you are pregnant, managing a heart, blood-pressure or other medical condition, or taking medication, consult a healthcare professional before use, and follow the manufacturer's safety guidance.
