The benefits of prescribing wild swimming for people with depression as an alternative option to medication is to be examined in a new study.

Experts at the University of Portsmouth are working with Sussex Partnership NHS Foundation Trust to look at the use of 'ecotherapy' – therapeutic intervention through nature – which is known to boost people’s mood.

Volunteers are being sought for the trial looking at the impact of immersion in cold water, which has been previously shown to reduce stress levels.

Some participants will be given a swimming course, to take place at Parliament Hill in London, Lenches Lake in Worcestershire and Saunton in north Devon, and will then be compared to a control group who are receiving their usual care.

Co-author, Dr Heather Massey, from the University of Portsmouth’s Department of Sport, Health and Exercise Science, said: “In this new study we are looking at outdoor swimming as part of social prescribing, which looks to support members of the community who are self-referred or referred by a number of professional organisations to community activities that will support them.

"It’s a step up in terms of scientific rigour.”

Read more: Into the blue: The health benefits of ocean swimming

If successful, the trial could add to further research which has credited cold water swimming for helping to ease depression and anxiety.

A 2018 study in the British Medical Journal titled ‘Open water swimming as a treatment for major depressive disorder’ looked at the case of a 24-year-old woman who had suffered with depression and anxiety her whole life.

After taking up open water swimming, she was able to reduce her medication, then four months later, came off it completely.

The study’s authors believe there were a number of reasons open water swimming helped to improve mental health in this case including the boost that comes from swimming and feeling part of a community, and a "sense of empowerment and achievement that comes with the mastery of such a challenging task".

Since then, researchers have followed up with a larger trial, but the results have yet to be published.

While the forthcoming research could be a step in the right direction in terms of exploring the impact swimming could have on wellbeing, it is important to remember that if you have been prescribed medication for a mental health condition you should continue taking it until advised otherwise by a medical professional.

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What is open water swimming?

Switching the comforts of a warm pool for a chilly pond, lake, reservoir, cold-water lido or the sea, might not be everyone’s dream dip scenario, but recent figures from Sport England suggest more than 4.1million people are regularly donning their bathing suits to go open-water swimming.

Meanwhile a quick scroll of the hashtags #coldwaterswimming and #wildswimming finds social media awash with images of wetsuit-clad swimmers of all ages, waxing lyrical about the virtues of taking a chilly dip.

So why are so many people discovering a love for swimming in open water?

Read more: Fancy an icy dip in -20°C? Meet the woman who does it daily

According to Laura Ansell, open water swimming coach and cold water specialist, wild swimming has likely seen a period of exponential growth because it remains very low cost to participate in, with local open water venues, beaches and rivers easily accessible for many to explore.

“Open water swimming is liberating, full of adventure, challenging and comes packed with loads of health benefits for both body and mind,” Ansell, who has a masters in sports science open water swimming and cold-water swimming, previously told Yahoo UK.

Watch: Top tips for wild swimming

What are the benefits of wild swimming?

Swim England says the health benefits of wild swimming are thought to include increased happiness, better sleep and improved circulation.

“Cold water or open water swimming is widely reported to have many benefits to both mind and body, from strengthening the cardio-respiratory system and immune system, to helping people to lose excess weight through the cooling of the body and then the rewarming process (thermogenesis),” explains Ansell.

“Cold water swimming also improves the body’s responses to stress, releasing endorphins which will help you relax, to sleep better and to feel calmer,” she adds.

The physiological effects of cold water swimming are widely touted too. Scientists have long been exploring a link between inflammation and depression, so it is not a surprise to learn cold water swimming could also help with this, given that it creates an anti-inflammatory response in the body.

A regular splash around in open water has also been linked to helping us become more resilient to stress, since being submerged in cold water triggers the body’s cold shock response.

A 2020 study conducted in Britain found that 61 people who took a 10-week course to learn to swim in cold seawater experienced greater improvements in mood and well-being than 22 of their friends and family members who watched them from shore.

There's also the psychological benefits of connecting with nature to consider. A study by Mind found 71% of participants noticed a decrease in depressive symptoms after a green walk.

There are socio benefits too, according to Ansell, including meeting others that share similar interests, trying something new, which can help us feel a sense of achievement and simply being outdoors helps us feel more relaxed.

Read more: Teacher endures freezing temperatures to go wild swimming every day for a year

Risks of wild swimming

While millions of people swim outside safely every year, the Outdoor Swimming Society warns there are a couple of things to be aware of before slipping into your wetsuit, as immersing yourself in cold water does come with certain risks including cold shock, incapacitation, cramp and hypothermia.

The society advises people to get expert medical attention before cold water swimming if they have a heart condition, high blood pressure, asthma or are pregnant.

It also advises you should only swim sober, and avoid cold water if you have a hangover.

How to get started

Take a swim buddy

Of course, you don’t have to go the full hog of swimming in ice-covered water to enjoy wild swimming. "It by no means needs to be that extreme. But if you are going to start open-water swimming, we advise you do so with caution and in the company of someone who is experienced," advises Vicky Allan co-author of The Art of Wild Swimming.

"If you don’t know a swimmer already, then join a local group, a list of which can be found on the Outdoor Swimming Society website."

Choose the right conditions

Never swim after heavy rain. Wait 48 hours for the water speed and quality to clear.

Get kitted out

"What you wear is not, I believe, really all that important. I wear just a basic swimming costume rather than wetsuit, but if neoprene is what you fancy, go for it," says Allan.

Rather than spend lots of money on expensive kit, she suggests starting off with just the minimum and building up.

"There are a few small bits of equipment that can make your swim more comfortable," she adds. "Neoprene boots or socks make entry into the water, particularly over stones, less painful, and also keep feet a little warmer. Neoprene gloves are also popular for protecting extremities from the cold."

A bright-coloured hat or swim cap is a good idea – not just to keep your head warm, but also so you can be spotted easily out there in the water.

"Many swimmers wear woolly hats on colder days, though these are no good, if like me, you like to get your goggles on and dip under," Allan says.

"The brightly-coloured tow-floats that swimmers are often seen trailing behind them, are also good for making you more visible if you get into trouble."

Enter the water slowly

"Do not jump or dive in – and keep initial swims short until you start to acclimatise," says Allan.

Make sure you acclimatise in the water to avoid cold water shock.

"As you enter the water it is important to regulate your breathing (do not gasp or panic)," Laura Owen Sanderson, founder of We Swim Wild and Wild Soul Swim, previously told Yahoo UK.

"Slowly enter the water (do not jump in). Once you are in up to your shoulders tread water for one-two minutes. The cold water shock response will pass after two minutes. Take this time to again regulate your breathing so it is calm. When you feel confident begin to swim."

Know when to get out

How long you stay in the water will depend on many factors, but the one key piece of advice is to listen to your own body and don’t stay in longer than you should.

"When you have been swimming for a while you will begin to acclimatise and you will naturally build up endurance," Owen Sanderson adds.

Follow the post-swim, keep warm rules

Whatever you wear in the water, however, it’s when you get out and what you do then that matters most when it comes to avoiding hypothermia.

"Bear in mind that your body temperature continues to drop, even after you’ve exited the water, so don’t wait till you actually feel cold to get out," Allan advises.

Making sure you get changed as quickly as possible is also important.

"A hot drink is always a good idea because it gets the heat to where it is needed most, your core," Allan adds. "And one of the most effective things for warming yourself is exercise – a few star-jumps or a bike ride home."

You can find more tips here.

Additional reporting PA.