In her new book Leap In: A Woman, Some Waves and the Will to Swim, journalist Alexandra Heminsley unravels the art of wild swimming. Her evocative prose reveals it to be a spiritual balm – one that’s all the more potent due to biting temperatures, unpredictable currents and the fear of the unknown lurking beneath.

“Sometimes I was too cold to move for a few moments, and would bend over, my fingers splayed behind me and my back to the sun, trying to make myself as wide as possible to catch the most rays,” she writes, of the aftermath of winter sea swims in Brighton.

“Within half an hour, I would be glowing from within, warm for the rest of the day. Like a hangover in reverse, I had done something that was painful for minutes but left me feeling well for hours.”

On a similar vein, in his book Dip: Wild Swims from the Borderlands, poet Andrew Fusek Peters describes in vivid detail how wild swimming saved him from crippling depression.

“Swimming is about feeling alive – whatever fear is in my head, as soon as I am in the water, it has gone, slam-splash-dunked,” he says.

The healing effect of swimming in the Great Outdoors appears to be double-edged.

The cold water immersion triggers a series of beneficial responses in the body and brain, while the act of bathing and swimming itself is therapeutic too; it’s no coincidence that hydrotherapy has been used as a cure for all manner of ailments since ancient times. 

Here, we examine a growing body of evidence that links cold water immersion to a host of anxiety and depression-relieving benefits.

“Swimming, because of its repetitive nature, is incredibly meditative,” Moby Coquillard, a psychotherapist and swimmer from California, tells Psych Central. “There’s even a built-in mantra, be this the slow count of laps, or self-directed thoughts like ‘relax’ or ‘stay smooth.’

“I teach a mindfulness-based cognitive therapy class for depression,” he adds, “and we use focus on the body here in the moment to keep past thoughts or future worries from invading our consciousness.”

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“All you have to do is show up at the regular time and you know there’s a good chance you’ll end up leaving the pool feeling a little better than when you arrived,” he adds.

A 1994 study by Berlin researchers observed a group of people who swam regularly in ice-cold water during the winter. They discovered “a drastic decrease in plasma uric acid concentration” amid participants, both during and after cold water exposure. 

This resulted in a “hardening” of the body, which triggered “an increased tolerance to stress”.

Another 2002 study from Washington-based scientists found that sitting in cold water for 15 minutes decreased the heart rate of volunteers by almost 10%, reducing blood pressure and leading to a calming effect.

“Since the density of cold receptors (the parts of our body that can sense cold) in the skin is thought to be three to ten times higher than that of warm receptors, the simultaneous firing of all skin based cold receptors from jumping into the cold may result in a positive therapeutic effect,” writes natural health therapist Dr. Peter Bongiorno in Psychology Today.  

Virginia researchers linked this effect to a potential treatment for depression.

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“Due to the high density of cold receptors in the skin [cold water immersion] is expected to send an overwhelming amount of electrical impulses from peripheral nerve endings to the brain, which could result in an anti-depressive effect,” they write, in this 2008 paper.

This stipulation is drawn from the effectiveness of electroshock therapy against depression; it’s thought cold hydrotherapy has a similar effect.

Numerous studies have linked cold water bathing to a reduction in the hormone cortisol.

In an article for Psychology Today, athlete Christopher Bergland labels cortisol “public enemy no. 1”.

While it performs lots of important functions, an undue increase in this chemical is related to a lot of different problems, including depression and decreased life expectancy. 

“Once the alarm to release cortisol has sounded, your body becomes mobilized and ready for action—but there has to be a physical release of fight or flight,” writes Bergland. “Otherwise, cortisol levels build up in the blood which wreaks havoc on your mind and body.”

“Swimming serves… to sop us excess fight-or-flight stress hormones, converting free-floating angst into muscle relaxation,” writes swimmer Jim Thornton, in an article quoted by Psych Central. “It can even promote so-called ‘hippocampal neurogenesis’ – the growth of new brain cells in a part of the brain that atrophies under chronic stress.” 

“When humans take a cold swim, once over the initial shock of the cold, it is usually very invigorating,” says Bongiorno.

“This is because wet and cold causes our surface vessels to vasoconstrict (tighten up) making blood move from the surface of your body to the core, as a means to conserve heat. Not only does it conserve heat,  it also reflexively bathes the brain and vital organs in fresh blood. This movement will bring nutrition, oxygen and also help gently detoxify the area.”

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Part of the effect of this is a lowered brain temperature, which in turn can relieve inflammation.

A number of recent studies have linked depression to inflammation, possibly even with inflammation as a causal factor. One theory is that inflammatory chemicals enter the brain, interrupting the production of serotonin there. 

A 2000 study from Prague scientists found that cold water immersion boosts dopamine levels by 530%.

This neurotransmitter is key to our experience of pleasure. In addition, cold water stress has been linked to an increase in both the “happy hormone” serotonin and beta-endorphins – a chemical with a morphine-like effect that’s central to pain management.

“The immediate mood-lifting effect of immersion in cold water” is probably a result of the stimulation of these dopaminergic pathways, says molecular biologist Nikolai Shevchuk in a key study on the impact of cold water immersion. “There is a lot of wellness research linking these brain areas to depression.”

“Humans used to spend a lot more time outside–and we were continually exposed to great variations in climate, humidity and weather,” explains Bongiorno. “And, there were occasions we would be  submerged in different waters of various temperatures too.”

“During our millions of years of evolution as primates, we were routinely subjected to ‘physiological stressors’ (like temperature fluctuations or even brief dips in cold water), which lead to the cascade of certain beneficial chemicals in the brain and body,” notes this article from Natural Mentor. 

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“Researchers hypothesize that depression could in part be caused by the nearly complete lack of physiological stressors in our comfort-driven, climate-controlled society.

“Cold water exposure thus helps us return to a natural state of balance by activating the sympathetic nervous system and increasing blood flow to the brain and core.”

Now you’ve been convinced of some of its emotional and mental health benefits, take a look at some of Britain’s finest wild swimming spots right here.

For help and support with mental health issues, visit mind.org.uk

Photos: iStock