Infrared saunas use specific wavelengths of light to heat the body directly. Unlike traditional saunas, they do not need to heat the surrounding air to extremely high temperatures. As a result, the body can experience a deep sense of warmth even at a relatively lower room temperature. This is one reason many people find infrared saunas more comfortable.

Their potential health benefits are mainly associated with stress reduction, relaxation, improved blood circulation, and relief from muscle and joint discomfort.

Major Health Benefits of Infrared Saunas

Relief from Stress and Mental Fatigue

A busy workday, excessive screen time, and constant mental activity can leave both the body and mind feeling exhausted. The warmth of an infrared sauna gradually helps the body relax and may reduce the feeling of tension stored in the muscles. Spending some quiet time in a sauna can also be mentally relaxing.

The warmth encourages the body's relaxation response, which may provide some relief from the stress and fatigue accumulated throughout the day. Some people report feeling calmer, lighter, and more relaxed after a sauna session. When used as part of a regular wellness routine, it may contribute to overall well-being.

Improved Blood Circulation

Infrared heat raises body temperature, which causes blood vessels to widen and blood flow to increase. This can improve the delivery of oxygen and nutrients to different parts of the body. Heart rate also increases during a sauna session, so the body's circulatory response can resemble some of the effects seen during light physical activity.

Improved circulation may be particularly noticeable as a feeling of relief for people who experience stiffness after sitting for long periods or after physical activity. However, sauna use should not be considered equivalent to exercise.

Relief for Muscles and Joints

Muscle soreness and stiffness are common after workouts, prolonged sitting, or intense physical activity. The warmth of an infrared sauna helps relax the muscles and increase blood circulation, which may reduce the feeling of accumulated tension in the body.

With better blood flow, the supply of oxygen and nutrients to the muscles increases, which supports the recovery process. This is why some people feel relief in their muscles and joints after using a sauna following exercise. Heat may also provide a soothing experience for some people dealing with arthritis-related stiffness or joint discomfort, although a sauna is not a treatment for any disease.

Improved Sleep Quality

Getting good-quality sleep requires both the body and mind to be relaxed. The warmth experienced during an infrared sauna session helps the body unwind and may reduce some of the physical and mental tension built up during the day. The relaxation that follows a sauna session can become a useful part of a bedtime routine for some people.

When the body feels more relaxed, falling asleep at night may become easier and sleep may feel more comfortable. However, if sleep problems persist for a long time, it is important to address their underlying causes rather than relying only on sauna use.

What Does Scientific Research Say About the Health Benefits of Infrared Saunas?

Infrared saunas are receiving increasing attention these days. Some people associate them with better blood circulation, while others consider them beneficial for heart health, pain relief, and recovery. But how strong is the science behind these claims?

The answer requires some balance. Research has been conducted on infrared saunas, but the evidence is not equally strong for all proposed health benefits. Clinical research so far has focused particularly on far-infrared saunas and Waon Therapy, a heat therapy developed in Japan. These studies have examined different aspects, including heart function, blood vessels, exercise capacity, pain, and stiffness.

Below, we will look at some of the important studies in this area. We will also examine who conducted the research, how many people participated, how the treatment was administered, and what the researchers ultimately found.

1. 2002 Research: Did Infrared Sauna Improve Heart Function?

One of the early important clinical studies examining the relationship between infrared sauna therapy and heart health was conducted by a team from Kagoshima University, Japan. The lead researcher was Takashi Kihara. Sadatoshi Biro, Masakazu Imamura, Shiro Yoshifuku, Kunitsugu Takasaki, Yoshiyuki Ikeda, Yutaka Otuji, Shinichi Minagoe, Yoshifumi Toyama, and Chuwa Tei were also members of the research team.

The study was published in the Journal of the American College of Cardiology on March 6, 2002.

How Did the Researchers Conduct the Study?

The research included 20 patients with chronic heart failure. Their average age was approximately 62 years, and all participants had NYHA functional class II or III heart failure.

The patients were placed in a 60°C dry sauna for 15 minutes. Afterward, they were covered with blankets and allowed to rest for another 30 minutes. This entire process was repeated daily for two consecutive weeks.

For comparison, 10 patients were placed in a control group. Their age, gender, and heart failure status were similar to those in the treatment group. They rested for 45 minutes in a temperature-controlled room maintained at 24°C.

The researchers wanted to determine whether repeated heat therapy could produce changes in how the heart and blood vessels function.

To investigate this, they measured flow-mediated dilation (FMD) of the brachial artery and levels of BNP (B-type natriuretic peptide) in the blood. FMD provides information about endothelial function, while BNP is an important marker used when evaluating heart failure.

What Were the Results?

After two weeks, 17 of the 20 patients who received sauna treatment showed improvements in their clinical symptoms.

Significant improvement was also observed in FMD. BNP levels decreased as well. The researchers also found an association between the changes in FMD and the improvement in BNP levels.

In simple terms, this small study found that repeated sauna treatment was associated with improved blood vessel function as well as improvements in certain heart-related measurements.

However, it is important to note that only 20 treatment patients participated in the study, and all participants had chronic heart failure. Therefore, it would not be appropriate to apply these findings directly to every healthy person.

Publication: March 6, 2002
Journal: Journal of the American College of Cardiology
Lead researcher: Takashi Kihara
Institution: Kagoshima University, Japan
Participants: 20 treatment patients + 10 control patients
PMID: 11869837
DOI: 10.1016/S0735-1097(01)01824-1

2. 2008 Research: A Study of Waon Therapy in 188 Heart Failure Patients

Further studies followed the 2002 research. Among them, a multicenter study published in 2008 attracted particular attention because it included considerably more patients than the earlier research.

The study was conducted by Masaaki Miyata, Takashi Kihara, Takuro Kubozono, and their colleagues. The researchers were affiliated with Kagoshima University, Japan.

Published in the Journal of Cardiology in 2008, the study included 188 patients with chronic heart failure and was conducted as a prospective, multicenter randomized study.

How Was the Research Conducted This Time?

All patients first received standard medical treatment for at least one week. They were then divided into two groups:

• 112 patients were assigned to the Waon therapy group.

• 76 patients remained in the control group.

The Waon therapy protocol was similar to that used in the earlier research. Patients were placed in a 60°C far-infrared dry sauna for 15 minutes and then covered with a blanket and allowed to rest in bed for another 30 minutes.

The treatment was administered daily for two weeks.

Researchers compared chest X-rays, echocardiography results, and BNP levels before treatment and two weeks afterward.

What Changes Were Observed?

Several heart-related measurements improved in the Waon therapy group.

For example:

• Left ventricular diastolic dimension decreased from 60.6 mm to 59.1 mm.

• Left atrial dimension decreased from 45.4 mm to 44.1 mm.

• Ejection fraction increased from 31.6% to 34.6%.

• BNP levels decreased from 542 pg/ml to 394 pg/ml.

Several of these changes were statistically significant.

However, there is an important point to consider. Some improvements were also observed in the control group, so it would not be correct to attribute every change solely to sauna therapy. This is why clinical research requires researchers to compare differences between treatment and control groups rather than simply looking at before-and-after numbers.

Even so, this study involving 188 patients added important evidence to the field because it used a larger sample and a multicenter approach compared with earlier smaller studies.

Publication: 2008
Journal: Journal of Cardiology
Researchers: Masaaki Miyata, Takashi Kihara, and colleagues
Institution: Kagoshima University, Japan
Participants: 188
PMID: 18922381
DOI: 10.1016/j.jjcc.2008.07.009

3. 2009 Research: Did Waon Therapy Improve Long-Term Cardiac Outcomes?

Previous studies had mainly focused on short-term changes following treatment. But one important question remained: if the therapy continued over a longer period, would it also have an effect on patients' long-term cardiac outcomes?

To investigate this question, Takashi Kihara and his colleagues conducted another study, which was published in the Journal of Cardiology in 2009.

Who Participated in This Research?

A total of 129 patients with chronic heart failure participated in the study. All patients were classified as NYHA functional class III or IV, meaning they had relatively severe heart failure.

• 64 patients received Waon therapy.

• 65 similar patients were placed in the control group.

The Waon therapy protocol involved:

60°C far-infrared dry sauna → 15 minutes

followed by:

Blanket-covered bed rest → 30 minutes

During hospitalization, patients received this treatment daily for 5 consecutive days. After discharge, they were advised to continue the therapy at least twice a week.

Researchers then followed the patients for approximately five years.

What Did Researchers Find After Five Years?

During the 60-month follow-up, 12 deaths occurred in the control group, compared with 8 deaths in the Waon therapy group.

An even more notable difference involved cardiac events. Events related to heart failure or cardiac death occurred in 68.7% of patients in the control group, compared with 31.3% in the Waon therapy group. This difference was statistically significant.

Based on these findings, the researchers concluded that, within this specific population of patients with chronic heart failure, Waon therapy was associated with fewer cardiac events.

However, this result needs to be interpreted carefully. This was not a study in which healthy adults were given sauna therapy to determine whether they would develop less heart disease in the future. The participants already had severe chronic heart failure.

Therefore, the appropriate interpretation is:

Among the patients with severe chronic heart failure included in this study, Waon therapy was associated with better long-term cardiac outcomes.

It would not be appropriate to interpret this research as evidence that infrared sauna prevents heart disease in healthy people.

Publication: 2009
Journal: Journal of Cardiology
Lead researcher: Takashi Kihara
Institution: Kagoshima University, Japan
Participants: 129
Follow-up: 5 years
PMID: 19304125
DOI: 10.1016/j.jjcc.2008.11.005

4. 2009 Research: Did Infrared Sauna Relieve Pain and Stiffness?

Research on infrared sauna therapy was not limited to heart patients. Researchers also investigated how heat therapy affects people dealing with conditions such as Rheumatoid Arthritis (RA) and Ankylosing Spondylitis (AS).

A pilot study in this area was conducted by Fredrikus G. J. Oosterveld and his colleagues. The research team was associated with Saxion University of Applied Sciences, Netherlands.

The study was published in Clinical Rheumatology in 2009, with online publication on August 7, 2008.

What Was Done in the Study?

The research included 34 patients in total:

• 17 patients had rheumatoid arthritis.

• 17 patients had ankylosing spondylitis.

Over a period of four weeks, all patients received a total of 8 infrared sauna sessions.

The researchers assessed pain, stiffness, fatigue, and disease activity during the treatment sessions and throughout the treatment period.

What Were the Results?

During the infrared sauna sessions, patients reported relief from pain and stiffness. This short-term improvement was statistically significant in both groups.

A reduction in fatigue was also observed, and patients generally tolerated the treatment well. Importantly, there was no relevant worsening of disease activity during the study.

However, when researchers looked at the overall four-week treatment period, the improvements in pain, stiffness, and fatigue were not statistically significant.

In other words, the strongest finding from this research relates to short-term relief. The study does not demonstrate that infrared sauna is a long-term treatment for rheumatoid arthritis or ankylosing spondylitis.

A simple way to understand this is that a patient may feel less pain and stiffness after a sauna session, but based on this small four-week study, it would be premature to claim that infrared sauna changes the long-term progression of the disease.

Publication: 2009
Online publication: August 7, 2008
Journal: Clinical Rheumatology
Lead researcher: Fredrikus G. J. Oosterveld
Institution: Saxion University of Applied Sciences, Netherlands
Participants: 34
PMID: 18685882
DOI: 10.1007/s10067-008-0977-y

5. 2012 Research: What Was the Effect on Blood Vessels and Exercise Capacity?

Another interesting study examining infrared sauna therapy and heart health was conducted by researchers at the University of Toyama, Japan.

The lead author was Takashi Ohori, along with Takashi Nozawa, Hiroyuki Ihori, Takuya Shida, Mitsuo Sobajima, Akira Matsuki, Satoshi Yasumura, and Hiroshi Inoue.

The research was published online in 2011 and appeared in the January 2012 issue of The American Journal of Cardiology.

What Did the Researchers Examine?

The study included 41 patients with chronic heart failure, with an average age of approximately 68 years.

Patients received Waon therapy five times per week for three weeks.

Before and after treatment, researchers measured several factors, including the 6-minute walk test, echocardiography, BNP, norepinephrine, FMD, and circulating CD34+ cells.

Cardiopulmonary exercise testing was also performed in 20 patients.

The Results Were Interesting

After three weeks, several important measurements changed:

Ejection fraction:
30.4% → 32.5%

BNP:
550 pg/ml → 416 pg/ml

6-minute walk distance:
337 meters → 379 meters

FMD:
3.5% → 5.5%

Several of these changes were statistically significant.

One particularly interesting finding was the relationship between improved blood vessel function, measured through FMD, and improvements in 6-minute walking distance.

In simple terms, patients who experienced greater improvements in blood vessel function also tended to show greater improvements in walking capacity.

In a multivariate analysis, the researchers identified an increase in FMD as an independent determinant of improvement in the 6-minute walk distance.

This research provides another indication that repeated Waon therapy may be associated with improvements in endothelial function and exercise tolerance. However, the same limitation applies here: the study involved patients with chronic heart failure, so the findings may have a different meaning when applied to healthy adults.

Publication: 2012
Journal: The American Journal of Cardiology
Lead researcher: Takashi Ohori
Institution: University of Toyama, Japan
Participants: 41
PMID: 21944673
DOI: 10.1016/j.amjcard.2011.08.014

6. 2016 WAON-CHF Study: A Larger Trial of Infrared Sauna in Advanced Heart Failure

Among studies examining infrared sauna and chronic heart failure, the WAON-CHF Study is particularly noteworthy. Compared with several earlier single-center studies, it used a stronger multicenter randomized design.

The research was conducted by Chuwa Tei and his colleagues and published in the Circulation Journal in 2016. Several researchers and the WAON-CHF Study Investigators were involved in the study.

How Large Was This Study?

The research was conducted across 19 institutes and included hospitalized patients with advanced heart failure.

A total of 149 patients participated:

• 76 patients → Waon therapy

• 73 patients → Control group

Patients were randomly assigned to either the treatment or control group.

The Waon therapy group received:

60°C far-infrared dry sauna → 15 minutes

followed by:

Blanket-covered bed rest → 30 minutes

This treatment continued for 10 consecutive days.

What Did the Researchers Measure?

The main focus of the study was changes in BNP levels. Researchers also examined clinical measurements such as NYHA functional class, 6-minute walk distance, and cardiothoracic ratio.

What Were the Results?

The Waon therapy group showed:

• Improvement in NYHA functional classification

• Improvement in 6-minute walking distance

• Improvement in cardiothoracic ratio

BNP levels also showed a trend toward improvement, although the treatment-related change in BNP did not reach statistical significance.

Another reassuring finding was that no serious adverse events were reported during the study.

This study is important because it involved multiple clinical centers and randomly assigned patients to treatment and control groups. In other words, it was not simply a small observational study in which a handful of patients were given sauna therapy and then monitored.

However, the participants had advanced heart failure. Therefore, the findings do not mean that every healthy person will experience the same cardiac benefits from infrared sauna use.

Publication: Online March 18, 2016; April 2016 issue
Journal: Circulation Journal
Lead researcher: Chuwa Tei
Institution: Waon Therapy Research Institute
Study: WAON-CHF
Institutes: 19
Participants: 149
PMID: 27001189
DOI: 10.1253/circj.CJ-16-0051

Conclusion

Based on the available clinical research, it is reasonable to say that far-infrared sauna and Wacom Therapy produce thermal effects in the body, and several studies have reported potential improvements in cardiovascular function, endothelial function, exercise tolerance, and short-term pain and stiffness.

However, the current evidence is not strong enough to consider infrared sauna a proven treatment for every health condition.

There is particularly a need for more research into its long-term health benefits in healthy adults. Larger studies with bigger sample sizes, longer follow-up periods, and better-controlled clinical trials would provide a more reliable answer.

Therefore, the most scientifically balanced and honest way to view infrared sauna today is as a wellness and supportive therapy, rather than as a proven treatment for disease.