Sauna Health Benefits
Regular sessions in the heat of a sauna bring you many health benefits, especially when combined with cold water immersion.
How can you get the most from sauna use?
An ideal sauna visit should be split into 3 or 4 sessions. The whole idea is to make your body super tolerant of temperature changes, and we do this by giving your body a surprise jolt (something it isn’t used to) or hormesis. Try and mix up the order and the times a little. Most modern saunas will have a combination of a hot sauna, a steam room and a cold plunge pool. Even in Roman times, this was a typical layout in public spas.
Saunas lower stress levels
Studies have shown that sauna sessions decrease cortisol levels in the body. Cortisol is the main stress hormone in your body, and whilst it may increase during the actual sauna, the subsequent reduction in stress levels can be pronounced. The concentration of endorphins in the blood may also increase, which may reflect the feeling of pleasure or discomfort induced by the sauna. The changes induced by the sauna in various circulating hormones are normalised within a couple of hours after the heat stress.
Another factor involved with general stress reduction is the stimulation and production of a brain neurotransmitter called BDNF (Brain-Derived Neurotrophic Factor) which is active in the hippocampus, cortex, and forebrain. BDNF allows our brain to change as we learn new things. BDNF improves processing speed, executive function, and memory. When BDNF levels are high, acquiring new knowledge is easier, memories are retained and people feel happier and less stressed. BDNF is critical for long-term memory.
Studies have shown that serum BDNF levels increased by 66% following a sauna session. Serum BDNF remained significantly higher than before the sauna session. Studies have also found that saunas can boost mood and alleviates depression.
Saunas give hormonal benefits
Sauna bathing stimulates hormonal changes, which include increases in levels of plasma renin activity (Renin is an enzyme that helps control your blood pressure and maintain healthy levels of sodium and potassium in your body). Saunas also stimulates cortisol, growth hormone and noradrenaline. The increases in levels of noradrenaline induced by sauna exposure can be similar to those induced by hard physical activity.
Saunas can keep your hormones in balance because it reduces the level of the stress hormone cortisol. This leads to a better control of insulin, testosterone, the thyroid, DHEA from the adrenal gland and estrogen.
Saunas reduce inflammation and C-reactive protein (CRP)
Inflammation plays a key role in the development of atherosclerosis and coronary heart disease. Sauna decrease the level of serum C-reactive protein (CRP) which is a marker of systemic inflammation and high stress. Studies show significant inverse association between the frequency of sauna bathing and the level of C-reactive protein. The more frequent the sauna use, the more robust the effect.
Sauna benefits
- Excellent stress relief
- Better sleep
- Positive hormonal changes
- Reduction in blood pressure
- Increases lifespan
- Improved heart health
- Reduces resting heart rate
- Increases metabolic rate
- Anti-aging benefits
- Better workout recovery
- Increased athletic performance
- Boosts the immune system
- Reduces inflammation
- Lowers C-reactive protein (CRP)
- Increases PGC-1α
- Triggers autophagy
- Hormonal benefits
- Higher endothelial NO synthase (eNOS)
- Lower reactive oxygen species (ROS)
- Breathing improvements
- Detoxification
- Reduced body odour
- Heat shock protein increase
- Increases AMPK and GLUT4
- Weight loss
- Skin and scalp improvement
Saunas increase lifespan… you live longer!
In recent decades, saunas have emerged as a tool to extend lifespan. Numerous studies show strong links between sauna use and reduced morbidity and mortality.
- Sauna use mimics physiological responses induced during exercise.
- Repeated sauna use optimises stress responses via hormesis and heat shock proteins (HSPs).
- Frequent sauna use may protect against cardiovascular and neurodegenerative disease.
- Sauna use preserves muscle mass.
In a 2018 study, higher frequency and duration of sauna sessions are each strongly associated with a reduction in fatal cardio-vascular disease in middle-aged to elderly people. The study covered the CVD outcome of the participants over a period of 15 years. The results showed a clear win for frequent saunas of good duration. A one-off sauna session isn’t really going to help.
It seems incredible that a sauna for 20 minutes, 3 or 4 times a week achieves reductions in morbidity that exceed prescription medication. Sauna use mimics a physiological response similar to moderate- to high-intensity cardiovascular exercise like cycling, swimming or running. Multiple studies have identified possible pathways for how regular saunas could reduce the risk of cardiovascular disease and mortality, including:
- Reduction in blood pressure.
- Improved function of the endothelium (the thin membrane lining in the heart and blood vessels).
- Relaxed blood flow.
- Reduction in oxidative stress and inflammation.
- Modulation of cholesterol levels.
- Increased HDL and decreased LDL.
- Positive impact on the nervous system.
Statins vs saunas? Doctors should prescribe saunas! Or even a cold shower.
Saunas increase metabolic rate
Basal Metabolic Rate (BMR) is the number of calories you burn as your body performs basic (basal) life-sustaining functions. It’s commonly also termed as Resting Metabolic Rate (RMR), which is essentially the calories burned if you stayed in bed all day!
We know that some things will drastically reduce your metabolic rate, such as calorie-controlled diets, hormonal problems and a lack of sleep. But the effect of saunas on metabolic rate are quite stunning. In a 1986 study, it was found that Metabolic rate increased by 25-33% after the first day of a sauna session. Blood proteins, Hb and Htc were significantly increased on the first and third days.
- Hematocrit (Htc) is a measure of the proportion of blood that is composed of red blood cells. High Htc levels are seen in athletes training at altitude, and sauna exposure has a similar effect.
- Hemoglobin (Hb) is an iron-containing protein that carries oxygen and carbon dioxide. It is located inside the red blood cells. In the cells of the body’s organs and tissues, the pH is slightly acidic, and the temperature is slightly warmer. The cellular environment causes hemoglobin to change its shape in a way that makes it more likely to bind to carbon dioxide and to release oxygen (which the cells need). Sauna exposure produces an increase in Htc. Doctors use the A1C test to measure glycated hemoglobin as an indicator of long-term blood sugar levels. Sauna use has been shown to lower glycated hemoglobin by 1% (which is better than exercise and dietary changes). Lower blood glucose levels are a good thing in terms of blood flow (see below).
PGC-1α is a protein that is a key regulator of energy metabolism and sauna heat exposure is known to stimulate these enzyme pathways. Repeated heat exposure upregulates heat shock proteins and AMPK which are both known to boost PGC-1α. It is also strongly induced by cold exposure. PGC-1α stimulates mitochondrial growth and promotes the remodeling of muscle tissue to a fiber-type composition. PGC-1α participates in the regulation of both carbohydrate and lipid metabolism. It is highly likely that PGC-1α is intimately involved in disorders such as obesity, diabetes, and heart disease. In particular it has a regulatory function in fat metabolism and the treatment of obesity and Type 2 diabetes.
Saunas have an effect on blood viscosity
It has to be pointed out that increasing red cell hematocrit increases the relative viscosity of blood. Studies have shown that saunas affect Htc levels initially, but prolonged sauna use (over 8 weeks) shows a negligible change. Increased hematocrit causes a disproportionate increase in relative viscosity. So, blood viscosity strongly depends on hematocrit. At a normal hematocrit of 40%, the relative viscosity of blood is about 4. The higher the blood viscosity caused by hematocrit, the blood flow decreases. But things get complicated…. an increase in blood temperature lowers blood viscosity (and therefore increases flow rate). This is why in a sauna, blood flows better near the skin at elevated temperatures.
Blood viscosity is affected by many factors, one of which is blood glucose levels. A study showed that increasing blood glucose levels from 100 to 400mg/dL increased blood viscosity by 25%, decreasing the blood flow rate by 20%. So the body has to compensate by opening up the blood vessels slightly (vasodilation) or increasing blood pressure.
Saunas cause excessive sweating, which can lead to dehydration, producing a decrease in blood volume, an increase in blood viscosity and, consequently, higher blood glucose levels.
To counter any negative issues a sauna has on blood viscosity (particularly for older men):-
- Get a blood test (to check for abnormally high Htc and Hg + blood viscosity). These are very inexpensive. Also, regularly check your blood pressure.
- Become a regular sauna user, and stick with it as your body, hormones, and metabolism will adapt for the good.
- Keep super hydrated with plenty of water and electrolyes.
- Sauna on an empty stomach when possible
- Don’t sauna after a heavy meal.
- Eat foods that have a low glycemic index (foods that have no/low glucose or release glucose slowly).
- Eat foods that thin the blood (cinnamon, ginger, garlic, turmeric).
- Eat foods that vasodilate and widen the arteries (Watermelon, beetroot, pomegranate, celery, dark chocolate, cabbage) You can also supplement with Arginine or citrulline, which produces Nitric oxide in the body.
- Eat a micro-nutrient rich diet.
- Don’t smoke!
- Don’t drink alcohol before or during a sauna session. Alcohol consumption during sauna bathing increases the risk of hypotension, arrhythmia, and sudden death.b
Saunas can trigger autophagy
Autophagy refers to an ordered and purposeful digestion of cellular components. It’s a normal cellular process that is key in preventing diseases such as cancer, loss of brain function, heart disease, diabetes, liver disease and infections. Researchers believe that autophagy is a survival mechanism that has anti-aging benefits. The body cleverly uses waste produced inside cells to create new building materials that aid in repair and regeneration.
When cells have plentiful supply of oxygen, glucose, amino acids and other essentials, they switch off or turn down the rate of autophagy. So taking a sauna, particularly on an empty stomach will put stress on the body and thus deplete your cells of oxygen and glucose which can trigger autophagy
Saunas reduce blood pressure and resting heart rate
Contrary to popular belief, sauna use does not lead to a reduction, but to an increase in blood pressure and heart rate during the actual sauna. There is also an increase in myocardial oxygen consumption during the sauna.
Blood pressure readings have two numbers, for example 120/80mmHg. The first number is your systolic blood pressure which is the highest pressure as your heart beats and pushes the blood round your body. The last number is your diastolic blood pressure, which is the lowest pressure when your heart relaxes between beats.
High blood pressure is called hypertension, and it’s the easiest stick your doctor has to beat you with in order to put you on medications. It’s a close second behind a cholesterol test to get you on statins. High blood pressure isn’t really a disease, it’s an adaptive response to more underlying problems. A sauna is a good option to reduce blood pressure without drugs.
The cardiac load during the sauna use corresponds to a moderate physical load of 60-100 watts. The heat of the sauna raises the surface temperature of the skin and the heart rate can increase to 100-150 beats a minute. But what happens after the sauna? Blood pressure shows an improvement in the days following a sauna session. The results are even better for people who take frequent saunas. During an Finnish study covering 22 years, the risk of high blood pressure was 24% decreased among men with a sauna frequency of 2-3 times a week, and 46% lowered among men who had a sauna 4-7 times a week. Additionally, saunas may also lower systemic blood pressure due to overall relaxation of the body and mind.
Resting heart rate tends to fall after regular sauna use. Evidence suggests that the effects of saunas go beyond relaxation. They may also improve cardiovascular function, reduce inflammation, and lower cholesterol. This results in a lowering of resting heart rate.
For optimal blood pressure, ensure that you are eating a diet with the correct balance of micro-nutrients:-
- Drink plenty of water.
- Ensure you have enough electrolytes (Sodium, potassium and magnesium). Don’t be afraid of salt.
- Improve your arteries with collagen, vitamin C, vitamin K2, vitamin D.
- Cut the processed foods and sugars.
- Omega-3 is vital (we recommend krill oil supplements).
- Get plenty of vitamin D, C and E.
- Vitamin B6, B12 and folic acid (B9).
- Thin your blood with natural cinnamon.
- Eat vaso-dilating foods
- Take an L-Arginine supplement.
- Exercise and be active.
- Reduce stress.
- Improve your kidney health.
- Improve thyroid health.
- Reduce insulin resistance.
- Acclimatisation in hot countries.
- Lose weight.
- Stop smoking.
Saunas improve athletic ability
Increasing your core temperature for short bursts in a sauna is not only healthy, but it can also dramatically improve athletic performance. Saunas improve your performance during endurance training activities by causing adaptations. These cumulative adaptations improved cardiovascular mechanisms. Your body also learns how to cope with changes in temperature. This helps optimise your body for subsequent exposures to heat generated during your next workout.
- Saunas also promote positive hormonal changes.
- Heat induces muscular hypertrophy (muscle hypertrophy involves the increase in the size of muscle cells and an accompanying increase in strength).
- Sauna use causes an increased release in growth hormone (HGH), which varies according to time, temperature, and frequency. The growth hormone effects generally persist for a couple of hours post-sauna. When saunas and exercise (particularly weights) are combined, they induce a huge boost in growth hormone
Saunas activate in Nrf2 and heat shock proteins
Heat shock proteins (HSPs) are expressed during the normal growth process of a cell, but also get induced in cells during various stress conditions produced by environmental changes, temperature, infections etc. HSPs exist in all organisms from bacteria to humans. They represent up 5-10% of the total protein. Under normal growth conditions they play a regulatory role in the folding of proteins, the transport of proteins and the repair or degradation of proteins. HSPs proteins are markedly induced (up to 15%) by sauna use. HSPs have been extensively studies for the treatment of cancer andf neuro-degenerative diseases.Skin and scalp improvement
As you sit in a sauna, your heart rate will elevate and blood flow will increase to the skin. At the same time, your pores get bigger and you start to sweat heavily. Sweating is the body’s cooling mechanism, but the sweat also flushes out the toxins that were locked within the pores. Clogged pores will open up for the first time. It’s a great idea to exfoliate with a towel at this stage, removing dead skin from the surface. Give your skin a good scrub after the sauna, and you will be rewarded with baby-soft skin.Saunas help your sleep patterns
Research suggests most adults optimally need about eight hours of sleep per night. Lack of sleep can increase your risk for stress, weight gain and chronic diseases. Every cell in our body follows a biological clocks that regulates everything from metabolism to repair. It’s called a circadian rhythm and it’s linked to the 24 hour cycle of day and night. Modern day living with it’s stress and external factors puts quality sleep at risk. Saunas produce a myriad of physical and mental benefits and most of these contribute to getting a better sleep.
Saunas aid detoxification via sweating
One of the biggest claims that sauna manufacturers make is detoxification. Almost as though all the waste is literally sucked out of the body!
- There is some evidence that toxins are released through sweat (fat-soluble toxins, heavy metals, ammonia, BPA, phthalates and uric acid). Sweat glands to play an important excretory function, similar to that of the renal system. It’s thought that they are responsible for clearing excess micronutrients, metabolic waste, and toxicants from the body. The role of the sweat glands in eliminating waste products and toxicants from the body seems to be minor compared with other avenues of breakdown (liver) and excretion (kidneys and gastrointestinal tract). Any pollutant that hides in our fat is unlikely to get released via a heavy sweat in the sauna.
- Eccrine sweat glands are the most numerous, distributed across nearly the entire body surface area, and responsible for the highest volume of sweat excretion. Apocrine and apoeccrine glands play a lesser role in overall sweat production as they are limited to specific regions of the body and impact the composition of sweat. Humans have 2–4 million eccrine sweat glands and they produce largely water and salt.
- The apocrine sweat glands are located primarily in the armpits, breasts, face, scalp, and pelvic areas. Apocrine glands produce viscous, lipid-rich sweat, which is also comprised of proteins, sugars, and ammonia.
- Apoeccrine glands develop from eccrine sweat glands between the ages of 8 to 14 years. They share properties with both eccrine and apocrine glands and are limited to the armpit area. The apoeccrine glands produce large salt water secretions similar to eccrine sweat.
- Sebaceous glands are not a type of sweat gland and are associated with hair follicles. Sebaceous glands secrete a viscous, lipid-rich fluid consisting of triglycerides, waxes and cholesterol.
So as you can see, the function of sweating is very complex. The process uses osmosis and ion exchanges and it actually needs fuel, mainly glucose, to proceed. Oxygen supply to the sweat gland is important for maintaining sweat secretion and ion reabsorption.
Sweat typically contains 40-60 mmol/L of NaCl. If we multiply this by 58 we get 2320-3480mg of Salt in a litre of sweat (2.32-3.48g). The release of salt through the pores is highly regulated, so it would reduce considerably if there is a low salt intake. In a typical sauna session of 30 minutes, a typical person would lose x litres of sweat. which is approximately a small teaspoon.
Saunas increase endothelial NO synthase (eNOS)
Endothelial cells form a single cell layer that lines all blood vessels and regulates exchanges between the bloodstream and the surrounding tissues. Signals from endothelial cells organise the growth and development of connective tissue cells that form the surrounding layers of the blood-vessel wall. eNOS is a key enzyme in production of the vasodilator, nitric oxide (NO) which is an important factor resulting in increased blood flow. It is a significant vasodilator and inhibitor of platelet aggregation and adhesion. eNOS a family of enzymes catalyses the production of nitric oxide (NO) from L-arginine.
Arginine is an amino acid that builds proteins, stimulates the secretion of growth hormone, assists with cell division, helps remove ammonia from your body, and has a role in healing wounds. Your body uses arginine to produce nitric oxide, which relaxes blood vessels, inhibits blood platelet aggregation and enhances cerebral blood flow.
Saunas increases NO production by the upregulation of the eNOS gene. Four-week sauna therapy showed a two-fold eNOS mRNA and protein expression compared with those without sauna exposure. Serum nitrate concentrations were increased by 4-week sauna therapy compared with those without sauna.
eNOS functioning is of extreme importance to vascular health. Alterations in this enzyme’s activity will cause the process called eNOS decoupling and lead to heart issues.
Interestingly, Red wine polyphenols sharply increase the expression and activity of nitric oxide synthase and nitric oxide release. red wine contains resveratrol which increases eNOS activity. So a glass of red wine could be a nice post sauna drink!.
Cold Immersion
The hot/cold experience elevates heart rate, adrenaline, and the release of endorphins. The best sauna session consists of 3 cycles of:-
- 10-15 minute hot saunas
- Cold plunge pool (or a cold shower) for 2-5 minutes
Scandinavian countries have some of the highest life expectancies in Europe despite freezing weather and long periods of winter darkness. Scandinavians are generally in great shape, and a lot of people believe that is to do with their tradition of alternating cold water plunges with sauna sessions. Hot and cold temperatures can benefit the body in a number of important ways, including improving the immune system and affecting metabolism.
The hot/cold experience has been practiced for thousands of years. It adds a new dimension to a simple elevated temperature sauna session. Many professional athletes use cold plunging regularly to boost their resilience and performance. The transition from a hot sauna to a cold pool causes your heart rate to increase. It also constricts your blood vessels and sends a sudden rush of adrenaline and endorphins racing.
Cold immersion has been recently championed by the Dutchman Wim Hof. The Wim Hof method advocates lengthy immersion in ice water. Exposing your body to cold temperatures is one of the three pillars of the Wim Hof Method. In recent years, cold body therapy has gained serious popularity, because it is linked to numerous health benefits. Professional athletes, bodybuilders, and celebrities have taken it further with whole body cryo therapy.
Frequent exposure to cold is linked to a number of health benefits. Scientists have found evidence that exposure to cold speeds up metabolism. Another benefit of exposing your body to cold is that it reduces inflammation, swelling, and sore muscles. Many athletes use ice baths and other types of exposure to cold as a means to speed up recovery after physical exercise. Cold exposure is also linked to improved quality of sleep, greater focus, and an improved immune response.
Brown Fat?
Brown fat, also called brown adipose tissue, is a special type of body fat that is turned on when you get cold (so it consumes calories). Brown fat produces heat to help maintain your body temperature in cold conditions. Brown fat contains many more mitochondria than does white fat. You have a small percentage of brown fat in your body compared to white fat. Brown fat helps you burn calories by creating heat right before your body starts to shiver (thermogenesis). It also helps regulate sugar (glucose) and fat metabolism. Mitochondria is made up of a lot of iron, which gives brown fat its colour.
Brown fat in newborns is located in their back, neck and shoulders. During childhood and adolescence, brown fat scatters around the body. Brown fat in adults is located around the neck, kidneys, adrenal glands, heart (aorta) and chest .
Steam room differences
Steam rooms share the same heat intensity as dry saunas, but the relative humidity is 100%. Saunas use dry heat typically from hot rocks while steam rooms are heated with steam from a boiler. Steam rooms are typically cooler than a dry sauna, but they can feel hotter due because the transfer of heat is greater from the steam compared to dry air.
Steam rooms reduce our ability to sweat, so it negates our main cooling mechanism. When you sweat in a steam room, the sweat, which is intended to cool you, doesn’t evaporate efficiently due to the moisture in the air. This leads to an increase in skin and core temperature.
Steam has the edge over dry saunas when it comes to breathing and congestion. Steam rooms can really help alleviate upper respiratory congestion. The combination of inhaling steam, usually mixed with oils, stimulates the sinuses allowing the nasal passage to clear and relieve congestion.
Steam rooms are typically tiled with the bench areas being open and wet. It’s a good idea to douse the seating in water and squeegie the water away before you site down (because you will sitting in other peoples sweat (or even worse pee!).
Hot and cold baths, an alternative
Many of us love nothing more than to soak in a hot bath to unwind after a stressful or tiring day. But only recently has science begun to understand how passive heating (as opposed to getting hot and sweaty from exercise) improves health.
The act of passively heating the body is what is shown to give the much studied cardiovascular benefits of which include lowered blood pressure and an increase in nitric oxide availability. Experiments have been done where individuals sat in a hot bath (40c) for 1 hour and had their body temperature and blood monitored. After the hour, their body temperature had only risen 1 degree but interestingly blood sugar levels were decreased and heat shock proteins increased significantly.
Although the heating achieved in a sauna is far greater, and the same benefits can be accomplished in a shorter time, running a bath may be the perfect quick fix solution when a sauna cannot be sourced. Bathing in hot water for its health benefits has been practiced for millenia.
Hot Springs and Thermal Medicine are an important cultural background all around the world.
Mineral and sulphurous bathing
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5397653/
