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How Cold Water Swimming Improves Stress Management

Mental health, 'Loony Dookers,' and polar bears.

Here in Scotland, ‘Loony Dookers’ dive into the chilly waters of the Forth Estuary on New Year’s Day, whilst members of the Polar Bear Club in New York take an Atlantic dip. Perhaps you did too? Similar events are held all around the world from Vilnius to Vancouver.

Source: Skeeze/Pixabay
Source: Skeeze/Pixabay

Whilst a few hardy souls have always taken to chilly waters all year round, the niche ‘sport’ of swimming in freezing waters is becoming increasingly popular. But why? It’s hard to fathom unless you are already a believer.

Cold water swimmers can seem almost evangelical about their post-swimming 'high’ and credit cold swims with curing depression, anxiety, and PTSD (as well as cancer, pain, and all manner of other afflictions). Whilst the historic use of hydrotherapy as a treatment for mental illness is suggestive, direct robust scientific evidence is scarce. One recent peer-reviewed case study makes the case for cold water swimming as a treatment for depression.

The most obvious mechanism through which cold water swimming (CWS) might improve mental health is in its effect on our stress responses. In brief, learning to cope with the extreme stress of cold water immersion may fast-track improvements in our ability to cope with all of life’s stresses. As a therapist, I’d say good mental health is built on our ability to cope with everyday stresses.

Over our evolutionary history, humans have evolved a range of automatic physiological responses to a perceived threat that prepare us for immediate self-preserving action: these underpin the well-known ‘fight or flight’ response.

Not surprisingly, cold immersion strongly triggers this same system.

On receiving a distress signal about a threat (such as a stalking tiger, or a dunking in cold water), the hypothalamus triggers the sympathetic nervous system by causing a burst of epinephrine (aka adrenaline) to be released from the adrenal glands. Epinephrine increases the heart rate, pushing blood to the muscles; widens airways allowing more oxygen to be sent to the brain, and mobilizes blood sugars as an energy supply. The release of cortisol keeps the system revved up until the threat is perceived to have passed and action is no longer required, and then the para-sympathetic nervous system takes over and returns the body to a resting state.

So far, so good. The flight or flight response seems a reasonable and useful immediate reaction to the threat of a sabre-tooth tiger, or indeed immersion in freezing seas.

However, in our modern world—where genuinely life-threatening situations are usually rare—our primitive stress systems often over-react, launching anxious fight or flight responses to low-level stressors such as traffic jams, work deadlines, a full inbox, or funny looks from others … It’s as if they are not properly calibrated.

Exacerbating the situation, parts of our brain then scramble to ‘understand’ or ‘ solve’ the threat that is perceived, typically falling straight into well-worn habitual anxious loops of thoughts (which may in fact have little to do with the real situation at hand), which typically create further stress. For example, the stress related to being stuck in traffic can quickly escalate in our minds to self-flagellation about other times we've been late, or to fears about missing a meeting, losing our jobs, failing to pay the mortgage, husband walking out ... you get the idea.

And chronic stress can lead to brain changes that contribute to maintaining anxiety, depression and addiction, compounding things further.

So, anything that 1) reduces our tendency to see neutral situations as threatening, 2) reduces our tendency to over-react to threats, or 3) allows us to get back to a calm baseline faster, will reduce stress and anxiety on a day to day basis.

Which is where cold water swimming comes in… A key study has shown that repeated three-minute dips in cold water over a period of time significantly reduces the adrenaline-driven sympathetic response to a different stressor and increases the para-sympathetic activity that calms the body down. In other words, our natural adaptations to cope with the stress of CWS lead to less reaction to other unrelated stresses, as well as to an ability to calm down faster too. This 'cross-adaptation' effect lasts for months.

There’s something really powerful psychologically about enduring and overcoming elemental ‘survival-like’ challenges such as CWS. Perhaps, at some level, they help re-educate our 'threat detectors' to understand what a real threat—that requires a bodily and psychological response - actually looks like?

Source: JohnHain/Pixabay
Source: JohnHain/Pixabay

Our modern worlds are geared to make us physically comfortable—comfortably warm, dry, well-fed. We are rarely out of our comfort zones unless we choose to be. Paradoxically, this can make the real—unpredictable—world seem more threatening. Similarly, when we are stressed or anxious we try to control our fears by restricting our world, which ironically tends to make us more fearful as we don’t get the chance to learn that we can in fact cope.

In contrast, overcoming and managing the shock of CWS can reconnect us with feelings of self-control, of endurance, and of trust that we can cope. It also requires us to learn to relax in the presence of extreme stressors—a most valuable life skill for day-to-day living.

Whilst many swimmers agree that cold water swimming puts anxiety in perspective, the short-term adrenaline high and beta-endorphin-dependent sense of well-being from CWS also seem particularly strong and addictive, and—it is claimed—enough reward in itself.

CWS also triggers a myriad of other effects which could act to return balance to stressed minds: reduced inflammation - high levels of which are linked to depression and anxiety; increased BDNF—implicated in neural plasticity, learning, and memory, which are linked to better mental health—see previous post; increased RMB3—a cold shock protein linked to synaptic plasticity; and generally enhanced circulation which may enhance neural (and other) functions through better perfusion.

Altogether, there's a powerful case that loony dookers and polar bears may not be so 'loony' after all... Surprisingly, cold water swimming may actually be the ideal antidote to modern life.

''OK, I 'get it,' but no way am I going in! ...''

Aww, go on ... It’s certainly cheaper than therapy for anxiety...

No? You don’t fancy throwing yourself in the January Atlantic? OK, fair enough.

In fact, whilst cold water addicts would undoubtedly say that total immersion in freezing cold water provides the best ‘hit,’ smaller exposures may also be beneficial. Turning the shower down to cold for 30 seconds, washing the face in cold water, and soaking the feet in cold water have all been shown to be beneficial.

Personally, I’ve made a tentative (swear-y, wetsuit-clad) start into the cold swimming world… I love it already!

What about you? Do you have a cold water swimming story to share? Does this post make you consider taking the plunge?

NB: If you are considering cold water swimming, do please read up on safe management first (e.g., here) and build up to it. Cold shock can kill as well as cure.


Tipton, M. J., Collier, N., Massey, H., Corbett, J., & Harper, M. (2010) Cold water immersion: kill or cure? Exp Physiol 102.11, pp 1335–1355. Retrieved from

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