Dr. Sarah King, ND
Now is a Great Time to Consider the Benefits of Thermotherapy
The crisp autumn air reminds us that winter is around the corner. As the temperature changes, now is a great time to consider the benefits of thermotherapy. Specifically, sauna bathing, when timed appropriately and paired with cold water exposure, can be beneficial for athletes, but also those who may be more sedentary with certain metabolic and cardiovascular disorders.1 Apart from the ability of thermotherapy to relax muscles, its effects on our brain are most interesting as it may provide an additional treatment for depression and, potentially, hyperactivity.
Types of Saunas
There are many different types of saunas: steam baths, dry-heat saunas, infrared saunas, and far-infrared (FIR) saunas. The temperature in the cedar-paneled rooms/compartments associated with dry-heat and FIR saunas is often kept between 70-100ºF. For optimal use, a sauna treatment is composed of between 5-20 minutes of heat exposure, followed by a cold shower or cold immersion. This can be followed with a room temperature recovery period before the cycle is completed again two or three times.2
By comparison to Finnish style saunas, which use dry heat or electrothermal heat conducted through large rocks, infrared saunas use infrared heat lamps to produce the required heat. Wavelengths in the infrared range of the light spectrum act predominantly on the blood vessels in the skin and tend not to penetrate deeper tissues2. In this way, sweating is promoted and increasing peripheral circulation is a main focus.
The state of hyperthermia from sauna use creates a thermal stress which activates the sympathetic nervous system and the Hypothalamic-Pituitary-Adrenal (HPA) axis. Studies are showing that heat thermotherapy may decrease cortisol levels and increase norepinephrine.3,4 Smaller studies have shown that women undergoing 20-minute sauna sessions twice weekly had an 86% increase in norepinephrine5 as well as increase in prolactin.6 Norepinepherine is a catecholamine associated with the stress response by providing alertness, enhancing memory retrieval and helping with focus and attention. What’s interesting is that although norephinepherine would normally lead to an increase in heart rate and blood pressure, we’re finding that the physiological response to sauna bathing actually leads to a decrease in blood pressure.
As part of activation of the sympathetic nervous system, the thermal stress from sauna bathing causes an increase in heart rate while decreasing peripheral resistance. This leads to increased peripheral circulation and a decrease in arterial blood pressure. So by participating in sauna bathing, this short-duration heat exposure may help to provide cardiovascular benefits to those unable to exercise in cold climates. It may also promote body mass loss in overweight and obese patients who are sedentary, as demonstrated by one study7. Subjects in a study using FIR sauna bathing lost almost twice as much weight and 4.6 times as much body fat as control subjects who instead participated in 15 minutes of cardiovascular exercise2.
The increase in body temperature activates heat shock proteins (HSP); proteins which act as protective coats for other molecules and proteins. An increase in HSP70 expression from heat stress has been shown to improve insulin sensitivity, lower glycated hemoglobin (HbA1C), decrease inflammation and decrease adiposity1. Depending on the patient, sauna bathing may be a beneficial treatment tool for hypertension and type 2 diabetes mellitus.
Apart from the cardiovascular benefits, researchers are investigating the mental aspects and benefits to sauna bathing. Animal studies have shown that short-term heat stress increases the expression of brain-derived neurotrophic factor (BDNF) when used in conjunction with exercise.8 BDNF promotes increases in the growth of new brain cells and assists in the survival of existing neurons.9 Other research is looking into how BDNF contributes to enhanced learning, and improved long-term memory10, as well as in the treatment of depression in cancer patients.11
Another interesting effect of sauna bathing is the increased levels of beta-endorphins and growth hormone in circulating blood plasma.2,12 Beta-endorphin is associated with what we call a “runner’s high.” These endorphins become activated after binding to mu opiod receptors to elicit that euphoric feeling after endurance or intense exercise. Dynorphin is a peptide that is responsible for the uncomfortable feeling associated with such intense exercise, as well as, exposure to extreme heat (sauna), and eating spicy foods. Dynorphin promotes the upregulation of these mu opiod receptors, effectively increasing the sensation of the “runners high” feeling.12 This same feeling can be obtained from the heat stress associated with sauna use, acting as an analgesic as well as increasing the sensation of enjoyment.
As a means of increasing that endorphin-associated pleasure, sauna bathing is being researched as a potential tool for depression. A small study of subjects participating in 20-minute FIR sauna treatments over four weeks showed improvements in somatic complaints and in their ability to relax.2
One case study looked at how sauna treatments would affect a teenage girl with anorexia nervosa. After performing regular and frequent FIR sauna treatments, the patient reported a gain in body weight, a reduction in hyperactive behaviour, and more emotional balance.2
Importance of Hydration
With the increase in peripheral circulation, and as a response to heat as the body attempts to cool the skin, sauna treatments tend to result in a decent sweat response. Sweating alone has some great health benefits. The body uses sweat as a means of eliminating heavy metals and toxin metabolites, such as BPA and phlalates.13
Due to the heat and sweat loss, maintaining proper hydration is critical. It’s also easy to feel lightheaded when immersed in sauna heat, due to the potential drop in blood pressure, so moving slowly and carefully is advised. It’s important to drink plenty of water leading up to a sauna session, throughout the sauna bathing, and continued after treatment. One indicator of dehydration is urine colour. Ideally, someone well hydrated exhibits a very pale yellow urine, as opposed to a medium or dark straw colour urine.
Sauna bathing may provide beneficial health effects, from increasing sweating, lowing blood pressure, increasing peripheral circulation (wonderful for those who tend to always have cold hands and feet), and promoting healthy brain function, including mood. Common with many thermotherapy “exercises,” best practice is to include short heat exposure (5-20 minutes), followed by a brief (30-60 seconds) cold immersion or cold shower. Additional benefits to circulation are seen when this cycle is repeated 2-3 times. Heat therapy is not advised for all patients, especially those who have recently suffered a myocardial infarction, so it’s important to discuss this with your doctor to ensure safe use of thermotherapy practices.
Image Copyright: <a href=’https://www.123rf.com/profile_akz’>akz / 123RF Stock Photo</a>
Dr. Sarah King is a licensed Naturopathic Doctor, graduating from the Canadian College of Naturopathic Medicine in 2014. Prior to completing her medical studies, she attended Nipissing University where she received her Honors Bachelor of Science in Biology. Sarah has a passion for women’s health and is a birth doula in Durham and Toronto Region. She treats a wide variety of health conditions including menstrual disorders and hormone balancing, fertility, prenatal care, digestive concerns, skincare and mental health/anxiety. Outside the office Sarah is an avid runner with a love of the GTA’s best forest trails. She also continues to improve her yoga practice and teaches breath work as part of stress management counselling to her patients.
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