Using heat as a means of purifying and healing the body is a well-known practice that's been used for thousands of years across diverse cultures. Think of American Indian sweat lodges, Russian banyas and Finland's favourite pastime.
Sauna use, or 'sauna bathing' as it's sometimes known, increases your core body temperature and starts off a cascade of hormonal, circulatory and cell-protective mechanisms that help the body to restore homeostasis. This response also primes the body for further heat stress.
Over the past few decades, some new and very interesting data has been emerging that suggests that sauna use may improve overall health and longevity. One study that particularly stands out is the Kuopio Ischemic Heart Disease Risk Factor (KIHD) Study which followed 2,300 men from Finland over a long period of time. Results of this study show a clear correlation between sauna use and a reduced risk of death and disease.
In the study, men who used a sauna 2-3 times a week were 27% less likely to die from heart disease than those who didn't use a sauna. What they also found was that the benefits were dose-dependent. Those men who used a sauna twice as much, experienced twice the benefits and were 50% less likely to die from heart disease, even with adjustments for age, activity levels and other lifestyle factors.
The KIHD study also highlighted the benefits of sauna use for preventing cognitive decline. Regular sauna use i.e. 2-3 times per week, reduced the risk of developing dementia and Alzheimer's disease by around 65%.
The study also discussed the potential benefits for mental health - men who used a sauna 4-7 times per week were 77% less likely to develop psychotic disorders.
The word "sauna" is likely to be of Finnish origin from the words savńa or sakna and means "earth pit" or "heated pit". Traditionally, saunas were heated with wood fires - and this is still a common practice observed in Finland today. The studies around sauna bathing have mostly been conducted in Finland, but other saunas exist, using electric heaters or infrared heat.
The heat in a sauna can range from 70°C to 100°C (158°F to 212°F), with an optimum level being around 80°C to 90°C (176°F to 194°F). Saunas can also be wet or dry. The Finnish practice of löyly involves throwing water on the heat rocks to increase humidity. Saunas, however, are not to be confused with steam rooms, where the high humidity actually puts more pressure on the heart and circulation as the sweat from the body doesn't evaporate properly to produce its cooling effect.
Finnish saunas last from 5 to 20 minutes, with some 'cooling off' periods mixed in. These might take the form of rolling in the snow, or jumping into cold water - what you may know as a 'plunge pool'. Although this does put stress on the heart and circulation, saunas pose little cardiovascular risks for otherwise healthy people.
What happens when you have a sauna?
When you're exposed to high temperatures in a sauna, your body responds pretty quickly as your skin and core body temperature rise, causing you to sweat. Your cardiac output - which is the amount of work your heart has to do to meet your body's oxygen demands - increases dramatically, but your heart rate and the amount of blood being pumped stay the same. During this time, the majority of the body's blood flow is redirected to the skin to help with sweating.
What's really interesting is that the more regularly you use a sauna or expose your body to this heat stress, the more the body acclimates itself to the heat, priming itself for future exposure. This is due to an effect called 'hormesis', any process in an organism that shows a two-phased response to exposure to increasing amounts of any substance or condition. Hormesis triggers various protective mechanisms in the body that stimulate cell repair and protect the body from future stressors.
The body's response to sauna use is very similar to that of doing increased-intensity exercise and has been suggested as an alternative for those who can't take part in exercise due to underlying health conditions or mobility issues.
Sauna use (in a similar way to fasting) stimulates the expression of heat shock proteins in our cells, which help to stabilise and repair damaged proteins in our cells and body. Damaged proteins are implicated in cardiovascular disease and in some neurodegenerative disorders such as Alzheimer's and Parkinson's disease.
Sauna use also stimulates specific cellular molecules and proteins that promote anti-inflammatory, antioxidant and anti-ageing functions. Without getting in to the nitty gritty statistics, studies support the therapeutic benefits of sauna use for:
Reducing inflammation in the body
Cognitive and mental health - including depression
Hormonal and metabolic health - including insulin resistance
Increased endurance and athletic performance
Detoxification of heavy metals, BPA and phthalates.
Saunas are not recommended for pregnant mothers, but are deemed relatively safe for healthy children over the age of 2 with adult supervision. Anyone with a pre-existing heart condition should consult a medical professional before using a sauna.
When using a sauna it's important to stay well hydrated before, during and after the sauna. The average person loses around 0.5kg of sweat during a sauna session - some people may lose even more than this. As sweat loss also means losing vital electrolytes such as sodium, potassium, magnesium and calcium, it's really important to follow a sauna with nutrient-dense foods to replenish these. Foods that do this are avocados, fish, nuts, spinach, tomatoes and seeds.
One thing for me, that's not so widely studied, is the therapeutic effect of the social aspects of sauna use. Before my local leisure centre closed for lockdown, I was using the sauna around 3-5 times a week. Not only did I enjoy sitting there, knowing about all of the various health benefits I was gaining, I also enjoyed catching up with people and meeting new people. I had some very interesting conversations in that sauna and met people of different nationalities, all enjoying the health benefits of heat. I'm very grateful for that.
I haven't been back there since lockdown in the UK, but am fortunate to have access to a woodland sauna in my neighbourhood. I also have a friend who just built one in their garden, so intend to take a trip over there very soon!
As the nights are drawing in, take a moment to reflect on the many health benefits of sauna use and consider incorporating this age-old practice in to your life to promote your own health and longevity. Can saunas help you live longer? Well, with the evidence to strongly support their therapeutic use, along with the opportunity to hang out with your loved ones for a catch up...I would say yes, they probably can.
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