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Evidence Based

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The Science Behind the Trend: Real Cold Exposure Benefits

Written by Dr. Ruscio on June 22, 2023

Written by Dr. Ruscio on June 22, 2023 — Reviewed by Hilary Watts

Unpacking the positive health effects of cold water exposure and the science behind why it works.

• Cold Exposure Benefits|
• How Does Cold Exposure Work?|
• Synergy: Cold Therapy and Other Lifestyle Practices|
• Landslide Benefits|

Chances are high you have at least one friend who’s told you about their experience with a cold plunge after a trip to the mountains or the cold showers they’ve started taking. Cold therapy (also known as cold exposure therapy and cold water therapy) has been trending all over the internet and social media, with people diving into freezing cold lakes and rivers, along with others simply standing in the shower with the knob turned to cold.

Often this activity is combined with sauna or hot tubs, alternating back and forth between cold and hot in settings like spas and bathhouses [1]. But what does the science say about the efficacy of doing something like this? Does the cold shock your body in a helpful way or a detrimental one? You might assume that this type of intervention (what some might call hippie-dippy or woo-woo) wouldn’t be supported by actual clinical science.

Interestingly—and fortunately—you’d be mistaken in that assumption. In fact, cold exposure benefits are supported by over 100 compelling scientific studies and include improvements in body composition, pain levels, thyroid hormones, and autoimmunity, to name just a few [2].

I personally love incorporating cold exposure into my wellness routine. My local gym has a cold tank that I often take the plunge in after the sauna, and it makes me feel amazing. 

The good news is that if you have access to running water, you have access to the benefits of cold water exposure, free of charge. Even better, some studies show that these benefits can be felt with just 30 seconds of daily cold exposure in one-to-two months’ time [3, 4]. In other words, you don’t have to do a full-on cold water immersion in a freezing lake or ice bath for five solid minutes in order to get cold water exposure benefits (although you can if you want to!). You can simply tack on 30 seconds of cold water at the end of your shower every day.

Let’s take a closer look at some of the science behind cold water exposure, the potential health benefits—including better sleep, improved energy, and even improved body composition—and why it works.

Cold Exposure Benefits

Much like every other health trend on the internet, there are both real and wild claims about what cold exposure might be able to do to improve your overall health and well-being. Importantly, I have to state that self-administered cold water therapy should not replace your regular doctor visits or cause you to believe you can take yourself off of any medications without medical supervision. Even if social media influencers say that they’ve replaced their Prozac or blood pressure meds with cold exposure, don’t start tinkering without talking to a healthcare provider.

With that caveat in place, let’s look at what the science says. There’s both anecdotal evidence and a number of randomized controlled studies that support a broad swath of cold exposure benefits, including [2]: 

• Improved immune function/reduced autoimmunity
• Better sleep quality
• Improved energy 
• Better mood/decreased depression
• Reduced anxiety 
• Improved body composition (reduction in body fat)
• Improved sexual desire
• Increased T3/balanced thyroid hormones  
• Increased gratitude

• Decreased stress
• Increased longevity
• Reduced inflammation
• Reduced blood lipids
• Better temperature regulation
• Reduced pain levels

That’s a huge list! It seems like just about everyone in the Western world could benefit from at least one improvement on this list. It’s kind of wild to think that a cold shower could do all this, and with no known side effects, it may be worth a shot to try it out.

Building a Habit

Interestingly, one of the studies I’ve referenced above did indicate that the study participants tapered off in their new habit of ending their showers with cold water after the required 60 days of the study, despite the positive impact it had on them [3].

When I see that type of quick recidivism, it reminds me that even adding 30 seconds of cold water at the end of a shower you’re already taking qualifies as a behavior change that requires habit-forming, positive reinforcement, and accountability—just like every other behavior change. Interestingly, combining healthy habits like exercise, breath work, and meditation with cold therapy actually enhances the positive results [3, 5]. More on that in the next section.

It would make a lot of sense to start habit-stacking some of these things together in order to better hold yourself accountable and remain motivated. If you’re already going to the gym, commit to ending your gym shower with 30 seconds of cold water, for example. Or place a laminated note in your own shower at home that simply says “30 seconds” as a gentle reminder for yourself. Simple shifts like this can go a long way to reinforcing a new habit.

How Does Cold Exposure Work?

The benefits of cold exposure therapy stem from both acute and chronic mechanisms. In other words, some immediate changes in your body can result during the therapy itself in the short-term, and then as you continue plunging over time, chronic longer-term exposure can have additional benefits.

Acute mechanisms that can lead to positive changes include [6]:

• Increased blood pressure (cardiovascular shock response)
• Increased heart rate
• Hyperventilation
• Vasoconstriction in the extremities
• Vasodilation in the core

These things don’t sound great on their own, but they’re happening due to a release of norepinephrine and the Lewis Hunting response as your body responds to the cold. Norepinephrine regulates arousal, attention, cognitive function, and stress reactions [2].

The Lewis Hunting response actually activates brown adipose tissue (brown fat) in your body, which can lead to positive health benefits. Brown fat breaks down blood sugar (glucose) and adipose (fat molecules) to create heat and help maintain body temperature. Most of our body consists of white fat, which stores energy, so it is more challenging to specifically target brown fat (7). 

A 2019 study at the University of California exposed 33 healthy, young men to cold temperatures (but not enough to make them shiver—nonshivering thermogenesis) for 2 hours to cause brown fat activation. This exposure increased branch chain amino acids (BCAAs)—valine, leucine, and isoleucine—which increase exercise endurance and reduce the risk of obesity, type 2 diabetes, and insulin resistance [6].

Chronic mechanisms of cold water exposure include [2]:

• Decreased cardiovascular health markers (ApoB/ApoA1 ratio, homocysteine)
• Reduced inflammation 
• Improved immune response
• Reduced oxidative stress 
• Increased antioxidants 
• Balanced stress hormones (ACTH, cortisol)
• Improved thyroid markers (T3, TSH)
• Increased zinc levels
• Increased norepinephrine
• Increased insulin sensitivity

Brown fat activation may also be partially a result of increased thyroid hormone in a chronic sense as well [8].

The benefits I mentioned in the first section of this article—fat loss, mental health, and mood stabilization, reduced inflammation, improved metabolic rate, increased lifespan—are all results of chronic exposure and the mechanisms above.

Synergy: Cold Therapy and Other Lifestyle Practices

As I mentioned above, there’s evidence to suggest that cold therapy may enhance other activities/stimuli, and other activities/stimuli may enhance the benefits of cold therapy [2]. This phenomenon is known as synergy—the sum is greater than its parts.

Cold exposure’s ability to induce brown fat activation is fairly unique in the research, making it a stand-out therapy for its positive effects on metabolic health. Other stressors, including sauna and physical activity, can enhance the benefits of cold water exposure and may lead to similar health outcomes when performed on their own. However, sauna and exercise do not appear to substitute cold therapy when it comes to activating brown fat [8].

Lifestyle practices that have been studied alongside cold exposure therapy include exercise, massage, sauna, and certain types of breathwork—specifically Wim Hof breathwork. Wim Hof breathing is a technique (named after the Dutchman who developed it) that involves cyclic hyperventilation and breath retentions (rapid breathing followed by moments of holding your breath) [5]. Wim Hof earned the nickname “Iceman” after doing extreme sports in extreme climates (like Mt Everest) wearing only shorts. His claim is that his cold water and breathwork combination helped him do it.

Exercise

A review of 104 studies showed that cold therapy can help prevent injuries, maintain performance levels, provide quicker recovery times, and reduce muscle damage that comes with strenuous exercise when done during the post-exercise recovery period [2].

A small clinical trial looked at the effects of cryotherapy on professional athletes engaging in high-intensity exercise. Cryotherapy is a different type of cold stress that uses air cooled with nitrogen. Although cryotherapy involves colder temperatures (-110 to 120 C for 2–3 minutes) than cold water exposure, both deliver similar effects via the Lewis Hunting response. People often choose cryotherapy if they can, because cold air is easier to tolerate than cold water [9].

The study found that the athletes who didn’t engage in cryotherapy after their strenuous workouts experienced worsened sleep quality, fatigue, and reduced exercise capacity compared to those who underwent cryotherapy.

Massage

A meta-analysis reviewed 99 studies looking at the best recovery therapies for post-exercise aches and pains—delayed-onset muscle soreness (DOMS), fatigue, muscle damage, and inflammation. Results indicated that massage was the most effective for reducing DOMS and fatigue, while both massage and cold exposure (contrast water therapy or cryotherapy) were most effective in reducing inflammation.[10]

Sauna

I mentioned earlier that some people like to alternate between cold and hot. The benefits of this method are known as the Lewis Hunting response, known for the scientist who first identified the benefits of the therapy. This practice is rooted in Eastern European and Scandinavian traditions.

A small study looked at Scandinavian swimmers who did both cold plunges and sauna. Their protocol averaged out to about 11 minutes per week of CWI and about 1 hour of sauna use per week (2–3 days for 10–15 min at a time). Compared to controls who did no sauna or cold therapy, the participants showed increased metabolism, lower levels of postprandial glucose, lower nighttime cortisol levels (beneficial for sleep), and improved temperature regulation [11].

A 2017 review compared the effects of “heat stress” (Finnish sauna use) and cold water immersion on the body and found that both led to health benefits. Sauna exposure/heat stress first causes vasodilation in the skin and skeletal muscle (the opposite effect of cold exposure/cold stress), increased heart rate, and reduced blood pressure. The authors did not find any evidence of brown fat activation in heat stress.

Over time, the body’s adaptation to heat stress may lead to better blood flow and overall cardiovascular health, higher metabolic rate, and stronger immune function (similar to cold exposure). It appears that the hormetic stressors (positive stress) of cold therapy and sauna have different mechanisms, but can lead to similar health benefits, especially for the cardiovascular system.

Although no research has directly revealed the mechanism, the authors of the study hypothesized that hot and cold exposure could augment each other to support better cardiovascular health. Sauna use may increase blood flow to the skin while cold water exposure causes that blood to flow inward towards the organs. Together, these effects push blood throughout the body, improving blood flow [1].

Breathwork

A small study specifically looking at a combination of Wim Hof breathing and ice-cold water immersion over the course of 10 days showed significant immunity improvements when test subjects were exposed to E. coli vs the control group. They exhibited fewer flu-like symptoms, produced a greater elevation in anti-inflammatory compounds and epinephrine, and produced fewer pro-inflammatory compounds than the control group [5].

Another study looking at the immunity effects of cold therapy combined with breathing techniques showed that the two techniques were greater than the sum of their parts. The breathing technique alone showed positive results, and the cold exposure alone group did not see benefit. But the favorable effects of the breathing techniques were significantly greater when combined with cold exposure. While targeted breathing techniques are effective for modulating immune function after a stressor, the benefits are much greater when combined with cold exposure [12].

If you’re interested in trying out the Wim Hof method, check out this free app. There are options to upgrade, but you can get a lot of information and get started with the free information on the app. It’s a helpful way to get started with this technique.

Landslide Benefits

It’s rare that I’ll unequivocally recommend an intervention, but cold exposure therapy may be about as close as I’ll ever get. The research to support the potential short-term and long-term health benefits of even brief cold exposure is too compelling not to consider. The fact that all you need is running water and 30 seconds a day to give it a try, and the low risk of side effects, give cold exposure therapy a hard green light from me.

While some researchers note that it may be difficult to tease out which anecdotal health benefits are directly attributed to cold therapy vs the effects of an already generally healthy lifestyle, it’s still worth trying cold exposure as an addition to your holistic wellness plan due to the potential synergy at play [2]. Adding cold therapy to your lifestyle plan has basically no downside and plenty of upside.

If you’d like some support as you venture into these icy waters, reach out to our clinic. We’d love to help.

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