Temperature Therapy Part 1: Sauna bathing for health

Bathing oneself in heat for the purposes of purification, cleansing, and health is an ancient practice, dating back thousands of years and observed across many cultures. Variations of its use are seen today in the banyas of Russia, the Hammams of Turkey, and most famously, the saunas of Finland.

Increasing lifespan and reduce cardiovascular disease

In recent decades, sauna bathing has emerged as a means to increase lifespan and improve overall health in multiple capacities, based on fascinating data from observational and interventional studies such as the Kuopio Ischemic Heart Disease Risk Factor (KIHD) Study which showed that men who used the sauna two to three times per week were 27 percent less likely to die from cardiovascular-related causes than men who didn't use the sauna (1).

Furthermore, the benefits they experienced were found to be dose-dependent: Men who used the sauna roughly twice as often, about four to seven times per week, experienced roughly twice the benefits – and were 50 percent less likely to die from cardiovascular-related causes. In addition, frequent sauna users were found to be 40 percent less likely to die from all causes of premature death. These findings held true even when considering age, activity levels, and lifestyle factors that might have influenced the men's health.

Dementia & Alzheimer’s

The KIHD also revealed that frequent sauna use reduced the risk of developing dementia and Alzheimer's diseasein a dose-dependent manner. Men who used the sauna two to three times per week had a 66 percent lower risk of developing dementia and a 65 percent lower risk of developing Alzheimer's disease, compared to men who used the sauna only one time per week (2).

Mental Health

The health benefits associated with sauna use influenced other aspects of mental health, as well. Men participating in the KIHD study who used the sauna four to seven times per week were 77 percent less likely to develop psychotic disorders, regardless of the men's dietary habits, socioeconomic status, physical activity, and inflammatory status (3).

Other benefits of sauna therapy include

Reducing Inflammation: Especially inflammation of the joints (arthritis) Sauna use has shown to reduce blood levels of CRP. In a study of more than 2,000 men living in Finland, CRP levels were inversely related to the frequency of sauna bathing in a dose-response fashion, with lower levels linked to greater frequency (4).

Enhances Cognitive function

Heat stress and exercise increase the expression of brain-derived neurotrophic factor, or BDNF (, a protein that acts on neurons in the central and peripheral nervous systems, to promote the growth of new neurons. BDNF modulates neuronal plasticity and can reduce anxiety and depression from early-life stressful events (5).

Promote Growth Human Hormone

Sauna use promotes growth hormone release, which varies according to time, temperature, and frequency. For example, two 20-minute sauna sessions at 80°C (176°F) separated by a 30-minute cooling period elevated growth hormone levels two-times over baseline, but two 15-minute sauna sessions at 100°C (212°F) dry heat separated by a 30-minute cooling period resulted in a five-times increase in growth hormone (6).

Improve Physical Fitness & Sports Performance

One small study of endurance runners showed that one 30-minute sauna session twice a week for three weeks post-workout increased the time that it took for the study participants to run until exhaustion by 32 percent compared to their baseline (7).

Enhances muscle growth

Maintaining muscle mass requires a balance of new protein synthesis and existing protein degradation. While new protein synthesis accompanies muscle use during exercise, protein degradation can occur during both muscle use and disuse. Therefore net protein synthesis is of extreme importance.

Heat acclimation, which can be achieved through sauna use, may reduce the amount of protein degradation that occurs during disuse by increasing Heat Shock Proteins (which I will explain below), reducing oxidative damage, promoting release of growth hormone, and improving insulin sensitivity (8).

Promotes Detoxification

Sweating promotes the excretion of certain toxins that accumulate in the muscle, adipose tissues, and organs of humans. These can include heavy metals, BPA and other chemical by-products the body is exposed to (9). As described above, sauna use induces substantial sweat losses, with the average person losing approximately 0.5 kg of sweat while sauna bathing.

How does the body react to heat stress?

Exposure to high temperature stresses the body, eliciting a rapid, robust response. The skin and core body temperatures increase markedly, and sweating develops (10).

The effects of heat stress are facilitated by molecular mechanisms that lessen protein damage and aggregation and activate endogenous antioxidant (NRF2 see last blog article), repair, and degradation processes. Many of these responses are also triggered in response to moderate- to vigorous-intensity exercise and include increased expression of heat shock proteins, transcriptional regulators (NRF2), and pro- and anti-inflammatory factors.

**The Key Players in the process**

Heat-shock proteins (HSPs) comprise a large, highly conserved family of proteins that are present in all cells. They play prominent roles in many cellular processes, including immune function, cell signalling, and cell-cycle regulation. When cells are stressed due to changes in their environment, cellular proteins can unfold or become damaged, impairing their normal function and further increasing their vulnerability to change. During exposure to stress from temperature extremes, cells increase expression of HSPs to stabilize unfolded proteins and repair or re-synthesize damaged ones. This phenomenon, referred to as the heat shock response, occurs at the expense of other cellular proteins to protect the cell from damage.

FOXO3

FOXO3 proteins play important roles in human body and are also activated following heat stress. FOXO3s regulate a vast number of genes that combat elements of cellular aging, such as damage to DNA, proteins, and lipids, and loss of stem cell function (11). They also increase the production of genes that regulate DNA repair, tumour suppression, stem cell function, immune function, and protein aggregation to further mediate the effects of aging and promote longevity.

As you can see, Sauna bathing is associated with many health benefits, from cardiovascular and mental health to muscle growth and athletic endurance. It is generally considered safe for healthy adults and may be safe for special populations with appropriate medical supervision. Heat stress via sauna use elicits responses driven by molecular mechanisms that protect the body from damage, similar to those elicited by moderate- to vigorous-intensity exercise and may offer a means to slow down the effects of some disease and aging.

I don’t know about you, but I’m definitely motivated to incorporate more regular sauna bathing into my life. Why don’t you try it for yourself starting with once a week and working it up to a few days if you can. And importantly, always keep yourself hydrated before, during and after your sauna session.

In health and love,

Deena x

Important: Please seek medical advice before planning to use a sauna if you have pre-existing heart conditions, high blood pressure, diabetic or are pregnant.