Contrast therapy is a technique that uses alternating hot and cold temperatures on the body for therapeutic purposes. It is a practice found in many cultures, from the traditional onsens of Japan to plunge pools and saunas in Scandinavia to the sweat lodges of Native American tribes. It has been used for many reasons, such as improving recovery, boosting energy levels, improving immunity, and promoting mental health. Our bodies produce cold shock proteins and heat shock proteins that are activated when exposed to temperature extremes. These are very beneficial as protection against cellular stress but reduce drastically without use. A way to activate them is to use the hot sauna followed by a cold plunge or ice bath. Doing these 2-3x a week can improve our ability to deal with temperature swings, reduce healing/recovery time, and increase our mental and physical resilience. Cycling between heat and cold at night in particular can be a great way to reset the autonomic nervous system and shift from a sympathetic “fight or flight” state to a parasympathetic “rest, relax, and digest” state, allowing for a great night sleep.
Cold (0C-18C)
Time recommended: 30 seconds to 30 minutes (2-6 minutes seems to be ideal)
Hypothermia does not occur right away; it takes time. At least 15 minutes, likely longer.
If you are new to cold plunging or haven’t in a while, it is recommended to familiarize yourself with cold water. Using a cold shower daily in the week leading up to a plunge can help. Start with 10 seconds and work up to 1-2 minutes. You can also consider going outside in the cold with skin exposure or turn down the heat/turn up the AC.
Once in the plunge, it takes 30-60 seconds to get your breathing under control; the first minute is the most challenging of them all! Cold water immersion is a time-based practice, so take your time and get comfortable with the cold.
After getting out, letting your body warm up naturally will give you the most significant benefits. If you step into a sauna immediately, your body will not have a chance to do an amazing metabolic workout. Gentle movement, like walking or horse stance, is recommended.
Benefits:
It has been demonstrated that cold water immersion around 14°C can effectively benefit mental health, increasing dopamine levels by up to 250% and norepinephrine (which is linked to vigilance, attention, focus and a positive mood) by up to 350%. It is thought that the shock of the cold water sends electrical impulses to the brain, which may act as a natural antidepressant and provide increased energy. Additionally, cold water exposure has been linked to improved circulation, digestion, metabolism, and immunity and increased levels of health-promoting antioxidants.
Your immune system is boosted. Those who use cold therapies experience fewer sick days. When your body is exposed to the cold, it can increase your production of health-promoting antioxidants. One study looked at subjects who swam regularly in ice-cold water in the winter. Following their chilly swim, they found a jump in their antioxidant glutathione levels.
Research indicates that submerging the body in cold water can activate the parasympathetic nervous system, leading to faster recovery. Additionally, this therapy may boost human growth hormone levels, further aiding recovery. It has also been found that cold water immersion therapy may improve sleep quality (especially when the body is fully submerged!).
Exposure to cold temperatures can activate brown fat, which is different from white fat. Brown fat helps increase body temperature but requires an energy source. Brown fat draws from white fat to maintain warmth. Babies tend to have more brown fat since they haven’t yet developed a robust shivering technique. While it was assumed that brown fat deposits decrease with age, this is only true for obese adults. Lean bodies have more brown fat. Cold exposure encourages the development of brown fat, raising your metabolism. Evidence shows that a higher ratio of brown fat can also improve sensitivity to insulin, which is responsible for transporting glucose from the blood to cells, which can be used for energy. Additionally, cold exposure can increase thyroxine, a thyroid hormone. Overall, it can raise your resting metabolic rate by up to 16%, allowing your body to burn more calories without extra effort.
Exposure to the cold can have positive effects on male fertility. Keeping testicular temperature between 31-37°C can lead to better DNA, RNA, and protein synthesis, resulting in increased sperm production. A daily cold dip can help with this temperature maintenance. Cold therapy can also increase testosterone levels up to 490% and reduce cortisol levels. All of these factors can contribute to improved fertility in men
Initially found to help with arthritis, cold therapy has since been shown to help with delayed onset muscle soreness, injuries, and neurological pains.
Exposure to the cold does not increase cortisol levels (a stress hormone), it can actually decrease cortisol levels with regular and consistent exposure.
When you force yourself to get in an ice bath, you prove to yourself that you have the ability to do difficult and uncomfortable things. This translates to your mental toughness in all areas of life.
Hot (80-110°C)
Time recommended: 5-25 minutes (10-15 minutes seems to be ideal)
It takes about 45 minutes to heat our traditional Finnish-style sauna, heated by burning wood in a sauna stove. Steam is created by throwing water on the rocks (löyly) that are heated on the stove. We keep the wood burning in the sauna to keep the stones hot and create steam. Sauna therapy has been used for thousands of years as a safe and effective form of detoxification, such as in Native American sweat lodges and Finnish wood-fired saunas. Drinking water with a bit of salt after using the sauna is recommended to replace lost water and electrolytes. Additionally, bring a towel and place it on the bench before sitting down, as the benches can get hot, and the towel will be there for any sweat loss. The average amount of time spent in the sauna is 10-15 minutes; however, this can vary from person to person, from 5 minutes to 25 minutes (which should be the maximum time spent)
Benefits:
Being in a Finnish or dry sauna can help purify the body by eliminating toxins through deep sweating. The hot air opens up the airways, clearing any respiratory congestion. Additionally, the rise in body temperature helps increase blood flow, delivering oxygen and nutrients to the body while helping to relax the muscles. A sauna session can also help to reduce stress by inducing the parasympathetic state, which allows the body to rest, digest and heal. Furthermore, it can help regulate hormone levels such as cortisol, aldosterone, beta-endorphin, growth hormone, testosterone, estrogen, and progesterone.
Research has demonstrated that regular sauna use can reduce the incidence of colds and flu by up to 30%. This is thought to be due to the sauna’s heat, which mimics a fever, increasing heat shock proteins and reducing viral replication. Furthermore, deep sweating can help improve skin cell turnover and remove bacteria from the skin, potentially enhancing skin health and reducing acne. Additionally, saunas can provide cardiovascular benefits similar to exercise, increasing heart rate and cardiac output while lowering blood pressure and increasing oxygenation and metabolic rate. For those with underlying heart conditions, saunas have been shown to be safer than exercise and can still provide comparable benefits.
A study conducted by researchers in Finland revealed that men who used a sauna 4-7x times a week for an average of 15 minutes had a 66% lower risk of developing dementia and a 65% lower risk of Alzheimer’s. Additionally, the more often the men used their sauna, the lower their risk was for sudden cardiac arrest, with a 50% lower risk of death from heart disease, a 63% lower risk of premature death, a 46% lower risk of hypertension, and a 40% lower risk of all-cause mortality. Although this study was conducted with men in mind, the same health benefits likely also extend to women. Sauna use is thought to promote brain health due to its ability to increase BDNF (brain-derived neurotrophic factor), which supports existing neurons and can help with the growth and differentiation of neurons. It also raises an individual’s resilience to stressors (hormesis), encourages autophagy (the natural death of old cells), stimulates serotonin production, and improves heart rate variability (a sign of decreased stress).
Risks to be aware of:
If you experience a lot of pain in your body after an ice bath, it may be a sign that you have stayed in the cold water for too long. Some tingling and new sensations are normal but knowing when your body is telling you to stop is essential. Symptoms that you have stayed in too long include feeling very cold, uncontrollable shivering, loss of motor skills, or confusion. While cold water immersion has many health benefits, it is crucial not to push yourself too far and risk injury. Take your time, gradually increase your time, and lower the temperature to get the most out of this practice.
Similarly, it is time to stop and get out of the sauna if you feel dizzy or faint. Saunas and cold immersions should not be used by the very old, the very young, pregnant women, those with very high or very low blood pressure, those with high fevers, infections, or inflammation, or those with heart disease or Raynaud’s Syndrome. The most dangerous applications of hydrotherapy come from complete body immersion for too long. Listen to your body and consider local applications and partial immersions instead, which are generally far less risky.
Written by Dr. Erica Mattia