Infrared sauna research

Infrared sauna benefits: what the research shows, and where it falls short

People buy infrared saunas for the heat, the quiet and a list of promised health effects. This guide checks the most common infrared sauna benefits against published studies, one claim at a time, and reports null and negative results as plainly as positive ones.

The short version: most studies behind the popular list of infrared sauna health benefits are small. Much of the controlled infrared data come from Waon therapy, a Japanese clinical protocol often tested in heart-failure patients, while the large long-term studies followed Finnish adults using traditional saunas and show associations, not cause and effect. Sauna Republic sells infrared saunas; nothing here is a health claim for any product.

How to read infrared sauna research

Association or experiment. Observational studies can show that frequent sauna use and an outcome travel together, not that one causes the other, because frequent users may differ in health, income or free time. Randomized trials are stronger, but heat is hard to disguise, so placebo comparisons are difficult.

Finnish or infrared. The large long-term studies used Finnish saunas at about 176°F (80°C); Cleveland Clinic notes that infrared saunas "typically land between 110 F and 135 F." Findings from one do not automatically transfer to the other.

One session or lasting change. A blood-pressure drop right after a hot session is not the same finding as lower resting pressure after months of use.

Size and support. Of 40 clinical studies of dry sauna bathing in a 2018 systematic review by Hussain and Cohen, only 13 were randomized controlled trials, and most had fewer than 40 participants. Clearlight supplied or loaned the saunas in two studies below, and both papers disclose it. Our guide to Clearlight saunas in published research covers both studies in more detail.

Each claim gets one of four grades:

Heart and blood vessels

What the Waon studies reported

In a 2001 before-and-after study, Imamura and colleagues reported that flow-mediated dilation, a lab marker of artery function, rose from 4.0% to 5.8% in 25 men with coronary risk factors (average age 38) after two weeks of daily Waon; 10 healthy comparison men were not treated. In 2002, Kihara and colleagues reported better symptoms in 17 of 20 heart-failure patients after two weeks and lower BNP, a blood marker of heart strain, while 10 matched untreated patients did not change; allocation is not described as randomized. In 2012, Ohori and colleagues reported that 41 heart-failure patients walked farther in six minutes after three weeks (from 337 to 379 meters), with no control group described. Most Waon papers cited here share an author, Chuwa Tei; among these studies, independent replication is limited.

WAON-CHF missed its primary endpoint

WAON-CHF, a multicenter randomized trial published by Tei and colleagues in 2016, assigned 149 hospitalized patients with advanced heart failure to 10 days of daily Waon or to a control group. Its primary endpoint, the change in BNP, did not reach statistical significance, and a 2017 sub-analysis confirmed that BNP did not differ statistically between groups. The Waon group improved in symptom class, walking distance and heart size, with no serious adverse events observed in either group, but secondary results from a trial that missed its primary endpoint are leads, not confirmation.

Beever's 2009 summary of published evidence on far infrared sauna benefits, in Canadian Family Physician, found limited moderate evidence for normalizing blood pressure and for congestive heart failure, and consistent fair evidence refuting cholesterol-lowering claims.

Blood pressure in healthy adults

In a 2022 randomized crossover trial by Hussain and colleagues, which Clearlight describes as an RMIT University study, 10 healthy women spent 45 minutes each resting, cycling and sitting in a Clearlight Sanctuary 2 at 140°F (60°C). Ear temperature rose most in the sauna, but blood pressure, arterial stiffness and heart rate variability did not differ between sessions; the authors concluded that the sauna's effects appear to be driven by heat responses "more so than exercise-mimetic" ones. Clearlight and a local distributor loaned the sauna.

In a 2026 Cardiff Metropolitan University study in Experimental Physiology, 12 healthy young adults each completed one 45-minute session in a Sanctuary 2 set to 149°F (65°C), with no comparison condition. Core temperature rose about 2.5°F (1.4°C), heart rate climbed from 74 to 153 beats per minute, and mean arterial pressure fell 9 mmHg right afterward while plasma volume contracted 11.6%: acute heat strain and fluid loss, not a lasting change. Clearlight provided the sauna and, according to the paper, had no role in the design or analysis.

Bottom line: mixed or small studies for heart failure and blood pressure, and evidence against the cholesterol claim. No infrared trial reviewed here shows a lasting drop in blood pressure in the general population.

The Finnish studies everyone quotes

The sauna longevity headlines come from Eastern Finland. In a 2015 observational cohort study in JAMA Internal Medicine, Laukkanen and colleagues followed 2,315 men aged 42 to 60 for a median of 20.7 years. After adjustment for cardiovascular risk factors, men who reported four to seven sauna sessions a week had a lower rate of sudden cardiac death than once-a-week users (hazard ratio 0.37, 95% confidence interval 0.18 to 0.75), with similar associations for fatal heart disease and death from any cause; only 201 men were in that group. A 2018 cohort from the same team, 1,688 adults of whom 51.4% were women, found the same pattern for fatal cardiovascular events.

The 2018 authors note that sauna habits were self-reported, that some confounding may remain, and that results from Finnish saunas at about 176°F (80°C) "cannot be directly applied to other type of steam rooms and warm water therapy." Commenting on the 2015 paper, the journal's editor, Rita F. Redberg, wrote that "we do not know why the men who took saunas more frequently had greater longevity." Bottom line: a consistent association with traditional saunas, not evidence about infrared. Our Finnish sauna vs infrared sauna comparison covers how the two heat types differ in practice.

Exercise recovery

The recovery studies used infrared cabins with healthy, active people, and the results are modest. In a 2015 within-subject study by Mero and colleagues, 10 active men sat in a far-infrared sauna at 95 to 122°F (35 to 50°C) for 30 minutes after training, or skipped it: after strength training no recovery measure differed, and after a maximal endurance session jump height was slightly higher. In a 2023 randomized crossover trial by Ahokas and colleagues, 16 male basketball players who sat in an infrared sauna for 20 minutes after resistance training, rather than resting, had a smaller drop in jump performance, milder soreness and better perceived recovery; sleep and night-time heart rate variability did not differ. A six-week study by the same group in 40 pair-matched female athletes found similar muscle gains with or without short post-training sessions.

Bottom line: mixed or small studies. Soreness is self-reported, the 2023 authors note that no placebo is possible, and nothing here shows faster tissue repair.

Mood and stress

Global Sauna Survey respondents said they use saunas "predominantly for relaxation," but whether heat itself lifts mood is a separate question. The best-known trial did not use a sauna: in a 2016 randomized trial in JAMA Psychiatry, Janssen and colleagues found that one session in a medical hyperthermia device, a tent-like enclosure with the head outside, lowered depression scores more than sham for six weeks in 29 analyzed adults with major depression.

The infrared trials are also small. Masuda and colleagues (2005) randomized 28 mildly depressed inpatients and reported that 20 Waon sessions improved physical complaints, appetite and relaxation scores, but mental complaints only slightly and not significantly. In a 2025 randomized pilot at UCSF, 30 adults with major depressive disorder all received cognitive behavioral therapy, and half added four sessions in a Clearlight Curve sauna dome that raised core temperature to 101.3°F (38.5°C). Depression scores fell substantially in both arms, slightly more with a low-heat sham, and the authors say the trial was not designed to compare them.

A 2026 meta-analysis by Rubanowitz and colleagues pooled seven small randomized trials of mixed heat methods (363 participants) and found a small effect on depressive symptoms (Hedges' g = 0.32), calling for larger trials. The only infrared cortisol study we found, by Ahokas and colleagues in 40 pair-matched female athletes, reported that next-morning cortisol rose after the first post-workout session and that the response declined over six weeks.

Bottom line: mixed or small studies for mood, and evidence against cortisol-lowering claims from one small study.

Pain, fibromyalgia and chronic fatigue

All of these studies are small. Matsushita and colleagues (2008) reported that 13 women with fibromyalgia had roughly half the pain after their first Waon session, in a case series without controls. In a 46-patient, two-group study by Masuda and colleagues (2005), pain improved whether or not four weeks of daily far-infrared sauna were added to a multidisciplinary program, though more of the sauna group had returned to work (77% against 50%). A 2009 uncontrolled pilot in 34 people with rheumatoid arthritis or ankylosing spondylitis (Oosterveld and colleagues) found less pain and stiffness during sessions but no significant change over four weeks, and a 10-patient chronic fatigue pilot without controls (Soejima and colleagues, 2015) reported less perceived fatigue.

Beever rated the chronic-pain evidence fair, from a single study, and the chronic-fatigue evidence weak. No study here measured everyday energy in healthy users. Bottom line: mixed or small studies.

Sleep

In the Global Sauna Survey (Hussain and colleagues, 2019), an online questionnaire, 83.5% of 482 self-selected respondents "reported sleep benefits after sauna use." The only infrared trial here that measured sleep, the 16-player crossover above, found no difference in sleep duration or quality, and a UCSF trial of infrared heat for insomnia is still recruiting. Bottom line: little or none.

Skin

The only positive skin study we found compared people rather than testing an intervention: Kowatzki and colleagues (2008) reported more stable skin-barrier and hydration measures in regular Finnish sauna users than in non-users, among 41 healthy volunteers. Sunlight research offers a counterpoint: a 2009 review by Cho and colleagues reported that infrared radiation and heat can each add to premature skin aging, though it did not study saunas. Red and near-infrared LED panels are a different technology, photobiomodulation, so LED results should not be credited to saunas; our Lumaflex red light therapy buying guide covers those devices. Bottom line: little or none.

Weight

The scale drops after a session because of sweat. Cleveland Clinic puts it plainly: "you will lose water weight, but that is not weight loss, that is dehydration," and the drop does not last once you rehydrate. Researchers who weighed 674 students around a dry-sauna visit (Podstawski and colleagues, 2014) noted: "One kilogram of body mass generally corresponds to 1 L of perspired fluid." The infrared weight study usually cited (Biro and colleagues, 2003) reported lower weight and body fat in 10 obese patients after two weeks of far-infrared sessions, but they also ate a fixed 1,800-calorie diet and there was no comparison group. Bottom line: evidence against lasting change. Our hydration and electrolytes guide covers replacing what you sweat.

Detox claims

Sweat does carry trace metals. A 2012 systematic review by Sears and colleagues found arsenic, cadmium, lead and mercury measurable in sweat across 24 reports, but methods "varied widely," the abstract's only sauna evidence is a single case report, and the authors called for "appropriately sized trials." In a 2022 within-subject study of 12 students by Kuan and colleagues, sweat from a 113°F (45°C) sauna cabinet of unspecified type held lower concentrations of nickel, lead, copper and arsenic than sweat from running, in micrograms per liter. No controlled study here shows sauna sweating lowering levels in the body. NIH sources note that healthy kidneys filter about 150 quarts of blood a day and that the liver helps "remove poisons." The NIH's complementary health center lists sauna use among detoxification approaches and says the few studies of such programs have been "of low quality." Our infrared sauna detox guide covers what sweat does and does not remove. Bottom line: little or none.

Infrared sauna benefits at a glance

Here are the benefits of infrared sauna use most often claimed, graded with the labels above.

What this means if you are buying

So, is an infrared sauna good for you? On this evidence, buy one for the heat, relaxation and routine you enjoy, not as a substitute for medical care.

Heat dose depends on temperature and time

The Cardiff team used 149°F (65°C) for 45 minutes to raise core temperature, and participants rated it "extremely hot"; the authors note that prior work at about 113°F (45°C) "reports limited net heat storage." Cleveland Clinic puts typical infrared saunas at 110 to 135°F, so do not assume an everyday session matches a study protocol.

Choose on fit, spectrum, power and warranty

Clearlight's Premier is far infrared only, at roughly 6 to 14 microns; the Sanctuary adds True Wave Full Spectrum heaters that also emit near and mid infrared, and both Clearlight cabin studies above used a Sanctuary 2 (our Sanctuary vs Premier guide compares the lines). The Premier IS-1, IS-2 and Sanctuary 1 run on a standard 120V, 15-amp outlet, the Premier IS-3 and Sanctuary 2 need a dedicated 120V, 20-amp circuit, and the Sanctuary 3, 5, C and Retreat need a dedicated 240V circuit. Our Clearlight saunas buying guide covers each model and its warranty, or browse the Clearlight indoor sauna collection.

For traditional heat as well, the Finnmark FD-4 Trinity (two people, 120V) and FD-5 Trinity XL (three to four people, 240V, electrician required) add a Harvia heater for traditional sessions, plus a 650 nm red light the studies here did not test. Our best indoor saunas guide compares infrared, traditional and hybrid cabins, and our infrared sauna vs steam room guide covers the steam option. If you plan to use HSA or FSA funds, read our HSA/FSA sauna guide before you order.

Safety: who should check first

A 2001 review in The American Journal of Medicine (Hannuksela and Ellahham) calls sauna bathing "well tolerated by most healthy adults," and Mayo Clinic says "no harmful effects have been reported with infrared saunas." Heat still carries risks.

Frequently asked questions

Browse the full infrared sauna collection to compare models side by side.

Clearlight, Sanctuary, Premier, True Wave and Curve are trademarks of Sauna Works, Inc., dba Clearlight Infrared. Sauna Republic is an authorized Clearlight dealer. Finnmark and Harvia are trademarks of their respective owners. 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.