Is cold exposure really as healthy as they say
Every winter, social media is flooded with videos of people plunging into icy lakes, standing under cold showers, or wading through snow in swimsuits. The comments fill up with enthusiastic reactions, but also skepticism. Is cold hardening and exposing yourself to cold – referred to in English as cold exposure – truly a path to better health, or is it just another wave that will recede in a few seasons as quickly as it arrived?
The answer isn't black and white. Behind what may at first glance appear to be nothing more than an Instagram trend, there is actually a growing body of scientific evidence. At the same time, not every enthusiastic claim made by influencers holds up under the scrutiny of medicine. Let's take a look at what we know about cold hardening and cold exposure, what we don't yet know, and how to approach the whole thing sensibly.
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From an Ancient Custom to a Modern Phenomenon
Exposing the body to cold is nothing new. Scandinavian nations have practiced winter swimming for centuries, in Russia plunging into icy water is a tradition associated with Orthodox holidays, and in Japan there is a practice called misogi – ritual purification under an icy waterfall. In the Czech Republic, cold hardening has a deep tradition associated with names like Sebastian Kneipp, whose hydrotherapy inspired generations, or with the Czech culture of sauna bathing followed by cooling down. Anyone who has ever visited a Finnish sauna with an ice-cold plunge pool knows what we're talking about.
However, the modern popularity of cold exposure was fundamentally influenced by one specific figure – Wim Hof, nicknamed the "Iceman." This Dutchman popularized the combination of breathing techniques, meditation, and extreme cold exposure, and with his feats (such as climbing Kilimanjaro in shorts) attracted the attention not only of the media but also of scientists. It was precisely thanks to studies conducted on Hof and his students that the scientific community began to focus on cold exposure more intensively, although it is important to add that research is still in a relatively early stage.
Podcasts and lectures by neuroscientist Andrew Huberman from Stanford University also contributed to the mass spread, as he popularized the topic of cold exposure and placed it in the context of neuroscience and physiology. Huberman's episodes on the effects of cold on dopamine, metabolism, and immunity have garnered millions of views and brought people to cold showers who would otherwise never have tried cold hardening.
But popularity also brings distortion. When a scientific study with twenty participants becomes a viral headline "Cold Shower Cures Depression," caution is warranted. That's precisely why it's worth looking at what science actually says – and what marketing noise adds to it.
The body's physiological response to cold is fairly well described. When you immerse yourself in cold water or expose yourself to low temperatures, the body reacts with a so-called shock reflex – breathing quickens, heart rate and blood pressure rise, and peripheral blood vessels constrict to protect the internal organs. The body begins producing noradrenaline and adrenaline, hormones associated with alertness, attention, and a feeling of energy. It is precisely this hormonal cocktail that is responsible for the characteristic feeling of euphoria that cold hardening practitioners describe after emerging from icy water.
A study published in the European Journal of Applied Physiology showed that immersion in cold water (approximately 14 °C) led to a two- to threefold increase in blood noradrenaline levels. Noradrenaline plays a key role not only in regulating attention but also mood – low levels of it are associated with depressive states. This is one of the reasons why people often report better mood and higher energy after a cold shower.
Another area that has attracted scientists' interest is the effect of cold exposure on brown adipose tissue. Unlike ordinary white fat, which serves as an energy store, brown fat burns energy and converts it into heat. Newborns have relatively large amounts of it, but it was long believed to virtually disappear in adults. Research over the past fifteen years, however, has shown that adults still have brown fat – and that regular cold exposure can increase its activity. A study published in the Journal of Clinical Investigation demonstrated that repeated exposure to mildly cold temperatures led to an increase in the volume and activity of brown fat in participants. This theoretically means a higher basal metabolic rate and better blood sugar regulation, although the practical impact on weight loss is, according to experts, rather modest.
Findings regarding the immune system are also interesting. A large Dutch study from 2016, published in PLOS ONE, followed more than three thousand participants who ended their morning shower with cold water (lasting 30, 60, or 90 seconds) for one month. The result? Participants in the cold shower groups reported 29% fewer sick-day absences from work compared to the control group. It should be noted, however, that the duration of illness itself did not differ – people went to work more often, but when they did get sick, they were not sick for a shorter period. This suggests that cold exposure may increase subjective resilience and vitality without necessarily directly strengthening immune defense in the classical sense.
And then there's the question of mental health. This is where anecdotal evidence is strongest – thousands of people around the world claim that regular cold hardening helps them manage anxiety, stress, and depressive episodes. Scientific evidence is still limited, but pilot studies exist that suggest a positive effect. One of them, published in Medical Hypotheses, proposes that a cold shower could function as a mild form of "electroshock" for the nervous system – a massive influx of electrical impulses from skin nerve endings to the brain could have an antidepressant effect. It is a hypothesis, not a proven fact, but the direction of research is promising.
But what does it look like in practice? Let's take the example of Martin, a forty-year-old programmer from Brno who started taking morning cold showers two years ago. "The first fourteen days were a pure battle with my own mind," he describes. "But after three weeks, I noticed that I felt much more alert in the morning and that stressful situations at work didn't throw me off as much. It's no miracle, but it's as if my threshold for what can unsettle me has been raised." Martin's experience is typical – most regular cold hardening practitioners don't talk about dramatic health transformations but rather about a gradual increase in resilience, better mood, and a feeling of having greater control over their body.
What Science Says – and Where Its Limits Are
Although research on cold exposure is growing, it is important to maintain a sober perspective. Most existing studies work with relatively small participant samples, short time horizons, and varying protocols (different temperatures, different exposure durations, different methods – shower versus immersion versus staying in a cold room). This makes it difficult to compare results and draw definitive conclusions.
As Professor Mike Tipton from the University of Portsmouth, one of the world's leading experts on cold physiology, points out: "People often confuse the fact that they feel better after cold water with the idea that cold water is objectively benefiting them. Both may be true, but one does not automatically follow from the other." This observation is key. A subjective feeling of improvement is valuable, but it is not the same as a clinically proven health benefit.
Moreover, there are risks that are not discussed much in the enthusiastic discourse. Sudden immersion in very cold water can trigger a dangerous shock reflex – uncontrollable gasping for breath, a sharp rise in blood pressure, and in extreme cases cardiac arrhythmia. For people with cardiovascular problems, high blood pressure, or certain other health conditions, careless cold hardening can be genuinely dangerous. Every year, drownings associated with cold water shock occur, even among experienced swimmers. Information about the risks of sudden immersion in cold water is summarized, for example, by the British Royal Life Saving Society.
Therefore, a basic rule applies: gradualness and common sense. Start slowly – perhaps with a short cold finish to your shower lasting fifteen to thirty seconds – and gradually extend it. Never venture into ice baths alone, especially not outdoors. And if you have any chronic health conditions, consult your intention with a doctor.
When we look at cold hardening and cold exposure in a broader context, an interesting perspective emerges. We live in an era when our body is almost constantly in a thermoneutral zone – heated apartments, air-conditioned offices, warm cars. An evolutionary biologist would say that our body was accustomed to significant temperature fluctuations for hundreds of thousands of years and that today's constant thermal comfort is, from an evolutionary standpoint, a complete anomaly. Regular cold exposure can be viewed in this light as a return to a more natural state – as mild stress (hormesis) that stimulates the body to adapt and strengthen.
The concept of hormesis – the idea that small doses of stress can be beneficial – is well established in science. It applies to physical exertion (exercise is a form of stress that strengthens muscles and the cardiovascular system), to certain plant compounds (polyphenols in vegetables are actually mild toxins that activate the body's defense mechanisms), and according to a growing body of evidence, to temperature stress as well. Cold exposure thus need not be either a passing fad or a miracle cure – it may simply be one of the tools for providing the body with stimuli that it lacks in the modern world.
Is cold hardening for everyone? Probably not. Some people love it and it becomes an integral part of their routine. Others try it and find that it brings them no significant benefit, or that it is simply too unpleasant for them. And that is perfectly fine. A healthy lifestyle is not about mindlessly following every trend but about listening to your own body and finding what works specifically for you.
What does seem certain, however, is that cold exposure is not merely a marketing invention. Behind the euphoria after an ice-cold shower lie real biochemical processes, behind the feeling of greater resilience lie measurable hormonal changes, and behind improved mood lie mechanisms that science is only beginning to fully uncover. As with most things in life, the truth lies somewhere between enthusiastic hype and cynical dismissal. And perhaps that cold shower tomorrow morning – that short, thirty-second one that you have to push yourself a little to take – is the simplest way to test it on your own skin.
