What is it:
The combination of sauna (or other heat therapies) and cold is often referred to as contrast therapy. In recent years, this protocol has gathered a lot of interest among athletes and active individuals looking to improve their overall health, sports performance, energy levels, and longevity. In Finland, where sauna bathing is part of the culture, it is usually associated with cooling periods in colder environments, either by taking a cold shower between sauna sessions, plunging in cold water (lake or sea), or by rolling in the snow in the winter. However, little research has been done on sauna and cold plunge combinations.
Sauna
The health benefits of sauna bathing are numerous and well documented, from reducing chronic inflammation, mortality, and Alzheimer's risk, to increasing cardiovascular health and immunity, among other things. Apeiron Life has a previous blog post on sauna bathing and its effect on sports performance.
Cold plunge
Cold therapy in its different forms has been studied in connection with reducing muscle pain and stress and improving recovery. Apeiron Life's cold therapy blog post dives deeper into the possible pros and cons of cold therapy and sports performance.
Purported claims:
Because heat and cold therapy have not been well studied in combination, it is somewhat difficult to separate what benefits are caused by one or both of the protocols.
Decreases the risk of chronic diseases
May boost immunity
Improves peripheral circulation
Reduce body adiposity and weight
Improve glucose metabolism
Decreases muscle soreness and fatigue
Reduces stress and anxiety
May improve sleep
What the science says:
The primary hypothesis behind the benefits of contrast therapy (and heat and cold treatment separately) is that although humans are homeotherms (an organism that maintains their body temperature at a constant level), the homeothermy needs to be challenged to remain healthy. In the last few years, we have seen numerous scientific papers reporting the exposure of otherwise sedentary healthy and unhealthy individuals to static, local, or whole-body heating, cooling, or a combination of both for being beneficial for a wide range of physiological responses, including resistance to cardiovascular disease, mortality, metabolic diseases, Alzheimer’s disease, hypertension, etc.
For example, a highly quoted Finnish study on regular sauna bathing shows that people who use saunas at least 2-3 times per week had a 24% lower risk of hypertension than those who did not use saunas regularly.
A few studies on cold exposure and hypertension show the negative. People who work in cold environments were at risk for elevated blood pressure. Similar effects of elevated blood pressure were seen in people who swam in ice-cold water, although the BP returned to regular levels after a few minutes of the swim.
Regular sauna bathing and its ability to improve the immune system has been one of the most researched topics regarding heat therapy’s health benefits. The Finnish Medical Society, Duodecim’s tests have shown that people who use saunas regularly have a 30% less chance of getting a cold than those who don’t. Another study from Finland discovered that a single sauna session increased the participants’ white blood cell counts. The study also revealed that the impact on the immune system was more significant in athletes than in the non-trained population.
The studies on whether deliberate cold exposure improves immunity or makes us more susceptible to colds are less clear. There are indications that hospitalizations and increases in respiratory infections go up during winter months, but studies also show that moderate, acute cold exposure has no detrimental effect on the innate component of the immune system. A study with athletic young men concluded that cold water immersion at 14C (57F) for 1 hour three times a week elevated blood concentrations of catecholamines and activated the immune system slightly. It is suspected that shorter periods in colder environments have similar positive effects on immunity, given that the person will not overstay the cold exposure.
From the cardiovascular health point of view, cold exposure results in vasoconstriction in limbs that enables the return of warm blood to the fingers and other distal body parts. It is likely to stimulate shear stress-mediated improvements in vascular function, leading to better health of the peripheral circulation. It is assumed that repeated extreme temperature variations, such as sauna bathing and ice-cold swimming, are powerful mediators of this effect. This evidence can be seen when returning to the sauna after a cold exposure by feeling intense pulsation sensations as blood flows back to the extremities.
Humans have two kinds of adipose (fat) tissue, white and brown. While white adipose tissue is good at storing fat, brown adipose tissue (BAT), in contrast, is good at burning energy. BAT regulates our body temperature in the cold and gets activated just before we start shivering. Studies have shown that repeated cold exposure increases the amount of metabolically active BAT and may lead to lower body weight. A study among Scandinavian winter swimmers who were accustomed to swimming in cold water followed by sauna session 2-3 times/week showed an increase in cold-induced thermogenesis prompting the researchers to suggest that sauna and cold plunge therapy could be considered as a potential strategy to increase energy expenditure. Both sauna and cold therapies benefit glucose metabolism and improve insulin sensitivity. The key to the positive metabolic effects of cold exposure seems to come from shivering, which increases energy expenditure and whole-body glucose and fatty acid utilization.
Besides the metabolic effect, one of the most promising health benefits of contrast therapy is its positive effect on mood. Both sauna and cold therapy have been shown to activate the sympathetic nervous system and increase the circulation of good feel hormones such as endorphins, dopamine, and serotonin. Because of these hormones, it can decrease muscle tension and pain. A relatively new study showed that applying cold and heat therapy within one hour after exercise could effectively reduce the pain degree of delayed-onset muscle soreness (DOMS) patients for 24 hours. A study in the Journal of Strength and Conditioning Research also showed that contrast water therapy was beneficial for recovery and fatigue up to 72 hours following team sports. Studies have also shown that both protocols can decrease cortisol and increase growth hormone levels, although heat exposure seems to significantly impact growth hormone release.
When it comes to sleep, the benefits of sauna are evident in research. Exposure to heat via sauna or hot bath will increase the body’s need to cool down before bedtime, enhancing the melatonin release, a hormone essential for sleep. Heat therapy has also been shown to increase slow-wave sleep (i.e., deep sleep), which usually gets harder to come by as we get older. In contrast, exposure to cold via an ice bath will increase your sympathetic nervous system activity and make you more alert. This might not be the best strategy before going to bed. However, people have different responses when it comes to temperatures, and some can feel extremely relaxed after a combination of hot and cold, so it comes down to personal preference whether you want to expose yourself to heat or cold or both before bedtime.
How To
In countries, where sauna bathing has been part of cultural behavior for hundreds of years, most people don’t consider it so much of a mode of therapy rather than a relaxing and pleasurable lifestyle habit.
A traditional dry sauna is heated to 175–210°F and the air is relatively dry, between 15-20% humidity. For people who are not used to the regular dry sauna, the heat might feel a bit too extreme. For those individuals, an infrared sauna that is less hot and uses EMF waves that penetrate the body and internally increase a user’s temperature is generally easier to take in.
A typical sauna bathing session usually lasts between 10–20 minutes, followed by a cooling procedure either via a cold shower, a dip in cold water, or just staying outside in cold air.
The cold plunge after sauna, where you submerge yourself in cold water up to your neck, should last 1-2 minutes and is usually done in a temperature between 40-60F. It’s important to start with a shorter time and warmer temperature if you’re not accustomed to it.
It’s also good to be aware that the cold plunge is going to feel more dramatic than the sauna and will lead to increased breathing and hyperventilation. Proper breathing technique is thus important to make cold plunge easier to manage and to prevent blacking out. You should reinforce nasal breathing and focus on slow exhales.
If you’re very sensitive to cold, you can keep your hands outside of water and wear a beanie. This will decrease the heat loss through your head and the possibility of getting dizzy from the blood loss to your brain.
Sauna and cold plunge protocol should end with the cold, which is usually considered most beneficial for health because it forces your body to reheat itself afterward.
More importantly, there is no right way to do a sauna and cold plunge. If you are generally in good health, you could do it several times a week and any time of the day, depending on what you want out of it. For some people, a sauna and cold plunge at the beginning of the day can provide a boost of energy, and for others, done at the end of the day can help them relax and sleep better.
Our take:
Extreme heat and cold are uncomfortable feelings and create stress in our bodies, and it is in this acute stress where the benefits lie. Whether you're looking for cardiovascular benefits, longevity, sports performance, better sleep, or managing stress, sauna, and cold plunge can deliver them both. Albeit, research seems to indicate that sauna is more beneficial when decreasing the risk of chronic diseases. Also, research suggests that regular sauna sessions in conjunction with sports training may further increase your cardiovascular fitness. It is also good to keep in mind, that cold therapy, especially if done daily and for a prolonged time, might attenuate training adaptations by hindering blood flow to the muscles and decreasing inflammation, which is necessary for muscle repair and growth.
There is a long history of using sauna and cold plunge for relaxation and health. People generally have different comfort levels regarding both extremes, and there are also sex differences. Women run physiologically colder than men, so they could possibly get the same benefits at warmer temperatures. Giving hard and fast rules regarding hot and cold protocols is complex and somewhat useless. Researchers such as Susanna Søberg, who has studied winter swimmers in Denmark, state that the sauna and cold plunge temperatures aren't exact. As long as we experience temperature changes, there will be health benefits and adaptations.
Will this benefit you?
Yes! Research is evident that everyone can benefit from regular hormetic stress, the ideal level of stress created by challenging our homeostasis with temperature changes, for example. Sauna’s effect on our health can be numerous, as stated before. When it comes to cold plunges, if you’re goal is to increase the amount of brown fat and metabolic health and lift your mood, it’s worth experimenting.
If you’re still interested, here’s what to keep an eye on:
However, it is important to remember that exposing yourself to drastic temperature changes can carry some risks for some people. Those with heart conditions or cardiovascular issues should always check with their physician before starting a sauna and cold plunge protocol. Cold plunge will increase the risk of hypothermia, and extra caution is warranted when you’re new to cold plunges. It is always important to dress correctly after cold exposure. Go with your comfort level both in the sauna and cold plunge, and start slowly.
References and additional reading:
Effects of heat and cold on health: https://journals.physiology.org/doi/full/10.1152/ajpregu.00115.2017?url_ver=Z39.88-2003
Sauna and hypertension: https://pubmed.ncbi.nlm.nih.gov/28633297/
Cold exposure and hypertension: https://pubmed.ncbi.nlm.nih.gov/14646271/
Swimming in cold water and hypertension: https://pubmed.ncbi.nlm.nih.gov/6101458/
Sauna bathing and common colds: https://pubmed.ncbi.nlm.nih.gov/2248758/
Cold exposure and respiratory infections: https://pubmed.ncbi.nlm.nih.gov/17705968/
Cold exposure and immune system: https://journals.lww.com/acsm-msse/Fulltext/2002/12000/Cold_exposure__human_immun
Sauna and white blood cells: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3916915/
Brown fat and cold exposure: https://pubmed.ncbi.nlm.nih.gov/24423363/
Winter swimming and Brown fat metabolism: https://www.cell.com/cell-reports-medicine/fulltext/S2666-3791(21)00266-4?
Heat therapy and insulin sensitivity: https://pubmed.ncbi.nlm.nih.gov/19203842/
Cold exposure and glucose metabolism: https://pubmed.ncbi.nlm.nih.gov/33764169/
Muscle soreness and heat therapy: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3808259/
Contrast therapy and fatigue: https://pubmed.ncbi.nlm.nih.gov/27398915/
Sauna and hormone response: https://pubmed.ncbi.nlm.nih.gov/3218898/
Sauna and growth hormone release: https://onlinelibrary.wiley.com/doi/10.1111/j.1748-1716.1986.tb08000.x
Endocrine effects of sauna and cold therapy: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8047510/
Sauna and depression: https://jamanetwork.com/journals/jamapsychiatry/article-abstract/2521478
Cold showers and depression: https://pubmed.ncbi.nlm.nih.gov/17993252/
Heat and cold for DOMS: https://pubmed.ncbi.nlm.nih.gov/33493991/
Sauna and sleep: https://ouraring.com/blog/sauna-sleep-a-winning-combo/
Heat and slow wave sleep: https://pubmed.ncbi.nlm.nih.gov/8736588/
Andrew Huberman podcast on hot and cold exposure:https://hubermanlab.com/dr-susanna-soberg-how-to-use-cold-and-heat-exposure-to-improve-your-health/
Sauna and cold plunge: https://www.drstacysims.com/blog/Cold%20Plunge%20or%20Sweltering%20Sauna
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