Infrared Sauna vs Traditional Sauna: What the Evidence Actually Says

Traditional Finnish sauna uses a wood or electric stove to heat the air in a room to very high temperatures (typically 80–100 °C / 176–212 °F). The body heats primarily through convection — hot air transfers heat to the skin surface. Humidity can be briefly raised by pouring water on heated rocks ('löyly'), creating a momentary steam burst.

Infrared sauna uses panels that emit infrared electromagnetic radiation, which is absorbed directly by tissues without first heating the surrounding air. The cabin air temperature is considerably lower — typically 40–60 °C (104–140 °F) — but the radiant energy penetrates the skin and subcutaneous tissue. A 2015 study in male athletes directly comparing the two found that heart rate elevation was substantially greater after traditional sauna bathing (92 bpm) than after infrared sauna (71 bpm), illustrating a meaningfully lower acute cardiovascular demand with the infrared modality.

The most compelling sauna health data comes from Finnish prospective cohort studies tracking traditional sauna users over years and decades. These studies found that frequent traditional sauna use (4–7 times per week) was associated with substantially lower cardiovascular mortality. A 2018 review in Mayo Clinic Proceedings synthesised this evidence, concluding that sauna bathing may reduce risk for vascular diseases and neurocognitive conditions.

However, that body of evidence is entirely specific to traditional Finnish sauna — operating at approximately 80 °C. The prospective cohort study published in BMC Medicine (Laukkanen et al., 2018) explicitly stated that findings from Finnish sauna bathing 'cannot be directly applied to other type of steam rooms and warm water therapy.' No equivalent long-term cohort study has tracked infrared sauna users over decades. The two research bodies are largely separate, and extrapolating Finnish sauna findings to infrared is not scientifically justified.

The infrared sauna evidence base is dominated by 'Waon therapy' — a specific Japanese protocol developed for congestive heart failure patients. A 2009 review in Canadian Family Physician found limited moderate evidence supporting far-infrared sauna for normalising blood pressure and treating congestive heart failure, but found that sauna therapy does not lower cholesterol or triglyceride levels. Critically, all studies reviewed were conducted by a single research group, limiting independent replication.

The most rigorous available RCT-level evidence comes from a 2025 systematic review and meta-analysis (Hamaya et al.) of 20 randomised controlled trials on passive heating modalities. The authors found no significant pooled effects for the majority of cardiometabolic outcomes — including cholesterol, glucose metabolism, and arterial stiffness. A modest systolic blood pressure reduction of approximately 4 mmHg was found specifically in whole-body heating interventions among people with existing coronary disease. The authors concluded: 'current RCT evidence does not conclusively support the effectiveness of passive heating for cardiometabolic health improvement.'

A recurring marketing claim for infrared saunas is that they replicate cardiovascular benefits of exercise — a useful selling point for those with limited mobility. A 2022 randomised crossover trial tested this directly: healthy women underwent infrared sauna sessions and moderate-intensity exercise sessions, with physiological measurements taken after each.

The study found that while infrared sauna elevated core body temperature, it did not produce meaningful differences in blood pressure, arterial stiffness, or heart rate variability compared to exercise. The authors concluded that 'physiological effects of infrared sauna bathing are underpinned by thermoregulatory-induced responses, more so than exercise-mimetic cardiorespiratory or cardiovascular activations.' In other words: the body heats up, which produces heat-stress responses — but this is not the same as the cardiovascular and metabolic demands of physical exercise.

A 2018 systematic review synthesised 40 clinical studies (3,855 participants) covering both Finnish and infrared sauna research. The conclusion on the central question is explicit: 'There is not yet enough evidence to distinguish any particular health differences between repeat Finnish-style and repeat infrared sauna bathing.'

The quality of that evidence base matters: only 13 of the 40 studies were randomised controlled trials, only 3 met Cochrane criteria for low risk of bias, and 21 of 40 studies involved 30 or fewer participants. This is not a verdict that infrared sauna does not work — it is a statement that the science has not yet reached the level of quality and volume needed to make that determination confidently in either direction.

Both sauna types produce genuine physiological responses: elevated heart rate, increased core temperature, sweating, and various heat-stress adaptations. Those responses are real, measurable, and have plausible mechanisms linking them to health. The question of whether they translate into long-term clinical outcomes — reduced disease risk, improved longevity — has not been settled for either type by controlled trials.

For most healthy adults, either type of sauna is likely safe when sessions are kept to reasonable durations, adequate hydration is maintained, and alcohol is avoided. The infrared modality's lower air temperature may be more comfortable for some users and produces lower acute cardiovascular demand — which may matter for people who find high-heat environments difficult to tolerate. Neither the 'infrared is superior because it penetrates deeper' nor the 'traditional is proven and infrared is not' framing is fully supported by existing evidence. Both are oversimplifications.