Alzheimer’s, Dementia, Sudden Cardiac Death & All-Cause Mortality
The two large studies in 2015 and 2017 looked at 2315 men in Finland over a period of 20.7 years. They looked at how frequent sauna bathing affected cardiovascular disease-related outcomes.
To make sure their results were accurate, they adjusted for things like blood pressure, resting heart rate, smoking status, Type 2 diabetes, previous myocardial infarction, LDL levels, and alcohol consumption.
After analyzing the data, they found that sauna bathing was associated with a 66% reduction in the risk of dementia, a 65% reduction in the risk of Alzheimer’s disease, a 63% reduction in the risk of sudden cardiac death, and a 40% reduction in the risk of all-cause mortality.
Congestive heart failure (CHF)
The largest and most recent study (2016) researching sauna therapy for congestive heart failure (CHF) involved 149 patients with advanced CHF.
The results showed that after 2 weeks of sauna therapy, the patients had a small but improved 6-minute walking distance, a reduced cardiothoracic ratio on chest X-ray (which means their heart size was reduced), and an improved NYHA classification of disease (meaning fewer patients were in class III and IV).
These results were compared to a control group that received standard medical care, and the sauna therapy group had significantly better results.
Infants with severe congestive heart failure (CHF)
A 2013 study that looked at 12 infants with a heart condition called ventricular septal defects (VSDs) and severe congestive heart failure (CHF).
The study found that when the infants underwent sauna bathing for 5 minutes a day for 4 weeks, the VSDs improved. This improvement was statistically significant, and it allowed nine of the infants to avoid surgery.
Ventricular arrhythmias in patients with CHF
In another study from 2004, 30 people with congestive heart failure and a high number of abnormal heartbeats called premature ventricular contractions (PVCs) were assigned to receive either sauna therapy or conventional medical treatment.
After two weeks, the group that received sauna therapy had significantly fewer PVCs compared to their baseline, while the control group did not experience any significant changes.
These results suggest that sauna therapy may be effective at reducing the number of PVCs in people with congestive heart failure.
Peripheral arterial disease
Two studies looked into how sauna sessions could affect people with peripheral arterial disease. This is a condition where the arteries in the legs become narrowed, making it harder for blood to flow.
The first study was a small trial that found decreased pain, improved walking distance, and improved blood flow in the legs after 10 weeks of sauna therapy.
The second study was a larger randomized controlled trial that also found decreased pain, improved walking distance, and improved blood flow in the legs after sauna therapy.
Ischemic heart disease
- Study: “Repeated sauna therapy improves myocardial perfusion in patients with chronically occluded coronary artery-related ischemia“ (2013)
- Short Summary: Sauna therapy may improve heart function in individuals with chronic total occlusion of coronary arteries.
A 2013 study looked at the effects of sauna therapy on people with ischemic heart disease, a type of heart disease caused by a lack of blood flow to the heart. It can lead to chest pain, heart attack, and other heart-related problems.
The study involved 24 people with chronic total occlusion of coronary arteries, which means that the arteries were completely blocked.
The study found that after 3 weeks of daily sauna therapy, the scores of defect reversibility on myocardial perfusion scans improved significantly compared to the control group that only received standard medical care.
Rheumatological and Immune-Mediated Disease
Rheumatological and Immune-Mediated Disease refers to illnesses that affect the joints, muscles, and other tissues in the body. These diseases are caused by the body’s immune system attacking its own tissues, leading to inflammation, pain, and other symptoms.
Examples of these diseases include rheumatoid arthritis, ankylosing spondylitis, systemic lupus erythematosus, systemic sclerosis, Sjogren’s syndrome, Behcet’s disease, and aortitis syndrome.
Rheumatoid Arthritis (RA) & Ankylosing Spondylitis (AS)
- Study: “Infrared sauna in patients with rheumatoid arthritis and ankylosing spondylitis“ (2009)
- Short Summary: Sauna therapy may temporarily reduce pain and stiffness in individuals with rheumatoid arthritis and ankylosing spondylitis, but does not affect disease activity.
A Dutch study looked at 34 patients with either rheumatoid arthritis (RA) or ankylosing spondylitis (AS).
The study found that after 4 weeks of sauna therapy, the patients with RA and AS experienced decreased pain and stiffness. However, this decrease in pain and stiffness was not sustained after the 4 weeks.
Additionally, the study found that there were no changes in disease activity in either group based on range-of-motion scoring and serum levels of ESR (erythrocyte sedimentation rate).
- Study: “Effects of thermal therapy combining sauna therapy and underwater exercise in patients with fibromyalgia“ (2011)
- Short Summary: Combination therapy of far-infrared sauna and underwater exercise may improve symptoms in individuals with fibromyalgia and other rheumatological disorders.
A study in Japan looked at 44 people with fibromyalgia, which is a condition that causes pain and fatigue. Some of the participants also had other rheumatological disorders, such as rheumatoid arthritis or systemic lupus erythematosus.
The study looked at how a combination of far-infrared sauna and underwater exercise therapy affected the participants.
It found that after 12 weeks of the therapy, the participants had lower pain scores, fewer symptoms, improved quality of life, and fewer tender points when examined physically.
Chronic fatigue syndrome/Myalgic Encephalomyelitis (CFS/ME)
- Study 1: “Effects of Waon therapy on chronic fatigue syndrome: a pilot study“ (2015)
- Study 2: “Waon Therapy is Effective as the Treatment of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome“ (2015)
- Short Summary: Sauna therapy may be able to help reduce fatigue and improve mental health in people with chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME). Two studies have found that using infrared sauna therapy for several weeks led to improved symptoms in a significant number of people with CFS/ME.
Two studies were conducted to see if sauna therapy could help people with chronic fatigue syndrome/myalgic encephalomyelitis.
In the first study, 10 people reported feeling less fatigued and had improved scores for anxiety, depression, fatigue, and performance status after 4 weeks of infrared sauna sessions.
In the second study, 15 people who received 8 weeks of regular far-infrared sauna therapy had 77.8% of them improve in symptoms compared to 50% of the people in the control group who did not receive sauna therapy.
Chronic Pain Syndromes
Chronic Pain Syndromes refer to conditions that cause long-term pain.
This type of pain can be caused by a variety of factors, such as an injury, illness, or disease. It can also be caused by a mental health condition, such as depression or anxiety.
People with chronic pain disorders often have difficulty managing their pain and may need to take medication or use other treatments to help manage their symptoms.
Two studies have been conducted to investigate the effects of repeated sauna sessions on these conditions.
The results of these studies showed that sauna therapy could reduce headache intensity, improve symptom scores, and reduce anger scores in patients with chronic pain disorders. Additionally, sauna therapy was found to improve somatic complaints, hunger scores, and relaxation scores in patients with mild depression.
Chronic Tension headache
- Study: “Efficacy of regular sauna bathing for chronic tension-type headache: a randomized controlled study“ (2015)
- Short Summary: Regular sauna bathing is a simple, self-directed treatment that is effective for reducing headache pain intensity in chronic tension-type headache.
A study in New Zealand looked at 37 people with chronic tension headaches. The study found that using sauna therapy for 6 weeks led to a 44% reduction in headache intensity in this group.
Chronic Pain Disorders
- Study: “The Effects of Repeated Thermal Therapy for Patients with Chronic Pain“ (2005)
- Short Summary: A combination of multidisciplinary treatment and repeated thermal therapy may be a promising method for the treatment of chronic pain.
A 2005 study looked at the effects of sauna therapy on people with chronic pain disorders.
The study found that people who received sauna therapy were more likely to return to work two years after the intervention than those who did not receive sauna therapy.
Additionally, the study found that the people who received sauna therapy had a decrease in their anger scores on the Cornell Medical Index (CMI) after four weeks of sauna therapy compared to the control group who did not receive sauna therapy.
The control group received the same courses of behavioural/rehabilitation/exercise therapy without additional sauna therapy.
Depression is a mental health disorder that can cause a person to feel sad, hopeless, and unmotivated.
It can also cause physical symptoms such as fatigue, changes in appetite, and difficulty sleeping. People with depression may also experience difficulty concentrating, low self-esteem, and thoughts of suicide.
Treatment for depression typically includes therapy, medication, and lifestyle changes.
Mild Depression (& Appetite Loss)
- Study: “Repeated Thermal Therapy Diminishes Appetite Loss and Subjective Complaints in Mildly Depressed Patients“ (2005)
- Short Summary: Sauna therapy improves appetite loss and general well-being in patients with mild depression.
In a randomized controlled trial involving 28 patients with mild depression, it was found that 4 weeks of sauna sessions improved somatic complaints, hunger scores, and relaxation scores, as compared to a control group that received bedrest instead of sauna therapy.
In this study, plasma ghrelin concentrations and daily caloric intake also changed in the sauna group compared to the control group.
Lungs & Airways
COPD (chronic obstructive pulmonary disease)
Two studies looked at the effects of infrared sauna therapy on people with COPD, a lung condition that makes it hard to breathe.
- Study: “Effect of repeated Waon therapy on exercise tolerance and pulmonary function in patients with chronic obstructive pulmonary disease: a pilot controlled clinical trial“ (2013)
- Short Summary: The addition of repeated sauna therapy to conventional therapy for COPD patients can possibly improve airway obstruction.
One study involved a group of 20 people who received sauna therapy for 4 weeks and compared them to a group of people who only received their usual medical care.
The group that received sauna therapy had slightly better results in a test of their breathing compared to the group that only received usual medical care, but there were no other differences between the two groups in terms of their breathing or ability to walk a certain distance.
- Study: “Repeated Waon therapy improves pulmonary hypertension during exercise in patients with severe chronic obstructive pulmonary disease“ (2008)
- Short Summary: 4 weeks of sauna sessions showed improved symptom scores, decreased pulmonary artery pressures during exercise, increased exercise times after sauna exposures and improved oxygen saturation during exercise in ex-smoker patients with COPD.
In the second study, a group of 13 male, ex-smoker COPD patients received 4 weeks of sauna therapy.
This group had a few changes in their health after the therapy: they had improved scores on a symptom assessment, lower blood pressure in their pulmonary arteries during exercise, longer exercise times, and better oxygen saturation during exercise.
These results suggest that infrared sauna therapy may be helpful for people with COPD in improving some aspects of their symptoms and physical functioning.
However, it’s important to note that these studies were relatively small and more research is needed to confirm these findings and determine the best ways to use sauna therapy for COPD treatment.
- Study: “The effect of six-weeks of sauna on treatment autonomic nervous system, peak nasal inspiratory flow and lung functions of allergic rhinitis Thai patients“ (2013)
- Short Summary: Infrared sauna therapy may be helpful in improving some aspects of allergic rhinitis.
In a study from Thailand, a group of 26 people with allergic rhinitis, a condition that causes symptoms like a runny or stuffy nose, received infrared sauna therapy as part of a 6-week rehabilitation program.
They were compared to a group of people with allergic rhinitis who only received their usual medical care.
The group that received sauna therapy had better results in tests of their breathing (peak nasal inspiratory flow rates and forced expiratory volume at 1 second) compared to the control group.
The researchers also looked at heart rate variability, but there was no significant difference between the two groups in this measure.
- Study: “Visiting a sauna: does inhaling hot dry air reduce common cold symptoms? A randomised controlled trial“ (2013)
- Short Summary: Inhaling hot air while in a sauna has no significant impact on overall symptom severity of the common cold.
In this study, 157 people in Germany who had the common cold were divided into two groups:
Both groups sat in a hot traditional sauna (90°C, 20% humidity) wearing a winter coat. The difference between these groups was that the test group breathed in the “hot dry” air of the sauna room, while the control group was made to breathe in “cool dry” air using a face mask.
The researchers found that the test group had slightly fewer cold and flu symptoms on the second day of the study compared to the control group.
Additionally, the test group took fewer doses of cold and flu medication on the first day of the study compared to the control group.
However, this difference was not seen on the third, fifth, or seventh days of the study.
This finding made the researchers conclude with the following: “We might have underestimated the effect of sitting in the sauna. For example, some participants experienced pleasant warming of the face and relaxation while sitting in the sauna and less headache afterwards. The warm feeling in a sauna during a cold might have more impact on symptoms than inhaling hot air, resulting in similar treatment outcomes in both groups. If so, we might have chosen the wrong research hypothesis.“
Sauna use for healthy individuals
Two small studies looked at the effects of sauna use on cholesterol levels in healthy men and women.
- Study 1: “The effect of sauna bathing on lipid profile in young, physically active, male subjects“ (2014)
- Study 2: “Effect of 30-minute sauna sessions on lipid profile in young women“ (2014)
- Short Summary: A sauna treatment lowers lipid levels in young men & women. “The positive effect of sauna on lipid profile is similar to the effect that can be obtained through a moderate-intensity physical exercise.”
The first study found that after 4 weeks of 45-minute sauna sessions, the men had lower total cholesterol levels and lower LDL levels compared to before the study.
The second study found that after 2 weeks of 30-minute sauna sessions, the women had lower total cholesterol levels and lower LDL levels compared to before the study.
Heart rate, blood pressure & hormones
- Study 1: “Changes in the lipid profile of blood serum in women taking sauna baths of various duration“ (2010)
- Study 2: “Effect of the sauna-induced thermal stimuli of various intensity on the thermal and hormonal metabolism in women” (2007)
- Short Summary: Heart rate, systolic blood pressure, levels of certain hormones and HDL levels (“good” cholesterol) increased, while diastolic blood pressure, plasma volumes and LDL levels (“bad” cholesterol) decreased after sauna use in women.
The same research group as above conducted two studies on the effects of sauna sessions on the bodies of 20 women. The studies involved either 30-minute or 45-minute sauna sessions, and were conducted over a period of 2 weeks.
The research found that sauna sessions had a number of physiological effects on the women’s bodies.
Specifically, their heart rate, systolic blood pressure (the pressure in the arteries when the heart is contracting), and levels of certain hormones (such as growth hormone and adrenocorticotropic hormone) increased after a sauna session.
On the other hand, their diastolic blood pressure (the pressure in the arteries when the heart is relaxing) and plasma volumes (the volume of blood plasma in the body) decreased after a sauna session.
The research also found that sauna sessions had an effect on the women’s cholesterol levels.
In the group that participated in 45-minute sauna sessions, their total cholesterol and LDL (low-density lipoprotein, also known as “bad” cholesterol) levels decreased, while their HDL (high-density lipoprotein, also known as “good” cholesterol) levels increased.
- Study: “Effect of Regular Sauna on Epidermal Barrier Function and Stratum Corneum Water-Holding Capacity in vivo in Humans: A Controlled Study“ (2008)
- Short Summary: Regular sauna bathing has a beneficial effect on the pH of the skin and the ability of the outermost layer of the skin (called the stratum corneum) to hold water. Specifically, regular sauna bathing appears to help maintain the pH of the skin at a healthy level and improve the skin’s ability to retain moisture. This can be beneficial for the overall health and appearance of the skin.
This study compared the skin physiology (the way the skin functions) of 21 regular sauna attenders (people who regularly go to the sauna) to 20 newcomer sauna attenders (people who are new to sauna attendance) before and after a sauna session.
The study found that, in the regular sauna attenders, the concentration of sodium chloride (a compound found in sweat) in the sweat decreased after a sauna session. This change was not seen in the newcomer sauna attenders.
The study also found that the levels of sebum (an oily substance produced by the skin) were lower in the regular sauna attenders before the sauna session, but both groups experienced a similar decrease in sebum levels after the sauna session.
Finally, the study found that the pH (a measure of acidity) of the skin was generally lower in the regular sauna attenders, but both groups experienced a similar increase in pH during and after the sauna session.
Detoxification is the process of removing toxins from the body. During detoxification, the body is able to flush out unwanted and harmful substances, helping to restore balance and health.
Two studies that looked at the effects of using saunas as part of a multimodal therapy (meaning a treatment plan that involves multiple different approaches) for people who have been exposed to toxic substances.
In both studies, the people involved reported improvements in their quality of life after going through the therapy, which included regular sauna sessions.
- Study: “Methamphetamine exposure and chronic illness in police officers“ (2011)
- Short Summary: A sauna detoxification protocol may alleviate chronic health symptoms appearing after chemical exposures associated with methamphetamine-related law enforcement activities.
In one of the studies, a group of police officers who had been exposed to toxic substances at work were given the therapy for 4-6 weeks.
After the therapy, they reported reduced number of “poor physical health” days, more sleep hours, and fewer symptoms of neurotoxicity (harmful effects on the nervous system) on questionnaires.
- Study: “Treatment of patients burdened with lipophilic toxicants: A randomized controlled trial“ (2009)
- Short Summary: Patients burdened with lipophilic toxicants reported improvements in their physical well-being after receiving sauna therapy, but no significant changes were noticed in neuropsychological testing scores or serum concentrations of selected organochlorides.
A study that looked at the effects of two different types of sauna therapy on people who had elevated levels of lipophilic toxicants* in their bodies.
(*Lipophilic toxicants are substances that can be absorbed easily into fatty tissues. They are usually found in heavily-polluted environments and can cause a range of health problems if not managed properly.)
The study included three test groups: 1) steam sauna + oral and intravenous supplements 2) dry sauna + placebos and 3) no sauna + no supplements.
The results of the study showed that both groups 1 & 2 reported improvements in their physical well-being measured by somatic well-being scores*, compared to the control group.
(*Somatic well-being scores are measures used to determine an individual’s physical health. These scores typically consider factors such as fatigue, sleep quality, pain levels, and general physical condition. A higher somatic well-being score indicates better physical health.)
However, there were no significant differences in neuropsychological test scores or in the levels of toxic substances in the blood between any of the groups.
- Study: “Health effects and risks of sauna bathing“ (2006)
- Short Summary: Sauna use reduced sperm counts, concentrations, and motility in 10 men, and caused abnormal changes in the structure of their sperm, as well as an increase in heat-stress related genes and proteins. These changes were reversible, and there were no significant changes in hormone levels.
In this study, 10 healthy men participated in a sauna activity program for 3 months, where they took 15-minute saunas twice a week.
The researchers found that after 3 months of sauna activity, the men had reduced sperm counts, concentrations, and motility (movement), as well as abnormal changes in the structure of their sperm. They also found an increase in certain genes and proteins that are associated with heat stress.
However, these changes reversed back to normal after the men stopped participating in the sauna activity for 6 months. The researchers did not find any significant changes in the men’s hormone levels during or after the sauna activity.
Sauna use for athletes
- Study: “Effect of sauna-based heat acclimation on plasma volume and heart rate variability“ (2014)
- Short Summary: Sauna bathing following normal training largely expands plasma volume in well-trained cyclists.
In a study involving 7 athletes, it was found that using a sauna for 30 minutes each day for 10 days after exercise caused an increase in the amount of plasma (a type of blood component) in the body by about 18% after 4 days.
This increase gradually returned to normal levels over the next few days.
- Study: “Sauna effect on blood oxygen transport and prooxidant-antio xidant balance in athletes“ (2012)
- Short Summary: The sauna provides adaptations of oxygen-binding blood properties and mechanisms of antioxidant protection via NO-dependent processes.
In another study involving 16 athletes, it was found that using a sauna caused an increase in body temperature by an average of 2.6°C after the first use, and an increase of 1.9°C after using the sauna regularly over a period of 5 months.
The study also found that using the sauna caused an increase in the pH level of the blood, a decrease in a blood component called base excess, an increase in the level of oxygen in the blood, an increase in the concentration of a protein called hemoglobin in the blood, and a change in the way oxygen attaches to hemoglobin, which allows for more oxygen to be released to the body’s tissues.
These changes were similar after the first and final sauna sessions, and were statistically significant.
Adverse side effects
- Review: “Clinical Effects of Regular Dry Sauna Bathing: A Systematic Review“ (2018)
- Short Summary: Only 8/40 studies on sauna bathing reported any adverse side effects, and six of those recorded mild symptoms.
A review of 40 studies on sauna bathing found that only eight of the studies reported any adverse symptoms from sauna bathing, and of those, six recorded mild symptoms such as heat discomfort or transient leg pain. None of the included studies reported severe adverse effects requiring emergency medical services.
In one study of heart failure patients, some mild symptoms such as low blood pressure and weight loss were reported, while in another study of patients with peripheral arterial disease, one participant experienced transient leg pain that improved over time.
In another study, some participants experienced coughing as a result of wearing a face mask during the sauna session. Overall, it appears that the majority of the studies did not report any significant adverse effects from sauna bathing.
Two of the studies reported moderate adverse effects, which are defined as symptoms that led to the withdrawal of study participants or changes in the study protocols.
One of the studies involved women with chronic fatigue syndrome/myalgic encephalomyelitis and found that most of the participants experienced heat intolerance, leading the investigators to reduce the temperature of the infrared sauna from 60°C to 45°C.
Another study of chronic pain patients reported that two patients dropped out of the treatment group due to acute bronchitis and claustrophobia experienced in the sauna room.