Cold showers may improve immunity, mood, and aid weight loss. Photo / 123rf
With growing evidence and potential risks, we speak to experts about taking the plunge
There are gentler ways to start the day than with an ice-cold shower, yet the potential health benefits – warding off illness, improving mood and helping with weight loss – could just be enough to make you consider braving the chill.
Prof Mike Tipton, a physiologist at the University of Portsmouth, has spent four decades studying how temperature affects our health. It’s a promising area of new research and, coupled with anecdotal accounts, might persuade you to turn the dial down to cold.
“For the people who say, I feel alive, awake, it sets me up for the day, I’m not going to knock it in any way. But there’s work to be done to figure out the mechanism,” he says. Read on to find out why.
One of the most rigorous studies into cold showers involved 3000 volunteers in the Netherlands turning the water to as cold as possible for the final 30, 60 or 90 seconds of their shower. A control group showered as normal.
After three months, results showed that those who included a cold water blast in their shower had taken 29 per cent fewer sick days – regardless of how long the water was cold for.
“My particular hypothesis is that the sudden change in skin temperature is driving a lot of the beneficial changes,” says Prof Tipton. “That sudden fall produces the cold shock response – a gasp, hyperventilation and increasing workload in the heart.
“Because it’s part of a fight or flight response, you’re activating the stress hormones, serotonin goes up and beta endorphins increase,” which contributes to boosting the immune system to ward off illness, he says.
Longer exposure to cold water is, of course, fatal, accounting for 60 per cent of deaths in cold water, Tipton says.
“This is a very double-edged sword. A minute in cold water may prime your immune system, five minutes may actually impair it. It’s the dose of cold that’s critical.”
Exposure to cold water may drastically improve mental health in patients, even when drugs have failed to do so, research suggests.
One study by Tipton and colleagues found that weekly cold-water swimming helped to ease a 24-year-old woman’s depression. She had previously spent seven years battling the condition, during which medication failed to reduce her symptoms.
“She said that she was the happiest she could remember being. A year later, she was drug-free and open-water swimming. She’d overcome a big challenge in her mind,” he says.
It’s not clear if a cold shower could have the same effect. “It may be the distraction of the cold water [that eased her depression]. When exposed to cold water, most people say all they can think about is the temperature and it takes their mind off everything else,” he says.
However, improvements in her mental health could also be down to the exercise involved in cold water swimming, overcoming the challenge of the cold, or the social inclusion of swimming with others, he noted.
“Is it the cold, or is it any one of these other things? We won’t know until there are studies that isolate cold exposure,” Tipton says.
Lukewarm water is the ideal for face washing, as it effectively removes dirt, oil and impurities without causing excessive dryness or irritation, explains Dr Anastasia Therianou, a consultant dermatologist on London’s Harley St and at Imperial College Healthcare NHS Trust.
However, cold water constricts blood vessels in the skin, which can reduce redness and inflammation – so can improve the appearance of skin, she says.
When it comes to hair, a cold shower can help lock in moisture. “Cold water closes the hair cuticles, so the hydration is ‘trapped’ inside the hair,” Therianou says. “This is beneficial for people with thin hair that tends to break easily. However, cold water cannot fully remove the excessive oils from the scalp so it’s advisable to wash your hair in warm water and then condition and rinse using cold water – if you can bear it.”
A review of more than 100 studies suggested cold water immersion, such as swimming or a cold bath, can activate and expand brown adipose tissue – a “good” fat that burns calories – and also reduce “bad” white fat, and therefore aid weight loss.
“The brown fat cells develop from white fat cells and, as their energy source, they like free fatty acids which they get from the white fat cells,” says Prof James Mercer, a professor emeritus at The Arctic University of Norway who co-authored the review. “By reducing the content of free fatty acids in the white fat cells, theoretically, one loses weight.”
However, scientists have not yet investigated whether a cold shower would also trigger this process. “My gut feeling is no, since the development of brown fat in cold water swimmers seems to require a very strong cold stimulus which I do not think you would get from a short cold shower,” says Mercer.
“A cold shower doesn’t provide the same stimulus as being immersed in cold water, as only about a third of the body is exposed to the cold,” says Tipton. “As a result, the cold shock response is roughly about a third of the size it would be in an immersion. That doesn’t mean it’s not big enough to have a positive effect – but nobody’s done the study.”
Athletes frequently turn to ice baths to aid their recovery, the idea being that the cold reduces blood flow, swelling and inflammation of the muscles.
Cold showers could have a similar effect, as the cold water is an analgesic (painkiller) and may be enough to decrease swelling, says Tipton.
However, he notes that while there is “some evidence” cold water can help muscle aches, the evidence “is not convincing across the board”. For example, some studies suggest that cold water actually lowers protein generation, which is vital for building and repairing muscle.
There’s anecdotal evidence of cold baths and cold water swimming easing very severe migraines, Tipton says. These accounts suggest short-term exposure to the cold may ease pain.
Cold receptors are located about 0.18mm below the skin surface and, when skin temperature drops quickly, these fire off an enormous amount of information to the central nervous system and the subsequent gasping changes blood flow in the brain, he explains.
“A reduction in pain could be down to a combination of those two things or other factors,” he says.
There’s anecdotal evidence from cold water swimmers that it dramatically improves their mood and wellbeing, says Tipton. “I work with the Bluetits [an outdoor swimming group in Pembrokeshire] and I am overwhelmed by the accounts of people who say it has changed their life. People are in tears about it.
“The vast majority of people who report benefits, say it’s to their mental wellbeing, although the mechanism behind this effect is unclear. The cold water is clearly activating people and waking them up, which will be down to the cold shock response and the release of stress hormones.”
Before stepping into a cold shower, it’s important to consider if you’re in good enough health to do so, says Tipton.
“We’re a tropical animal that wants to be naked in 28C. Taking that animal and showering it with 10 or 12C water is a really stressful thing to do,” he says.
The cold triggers cold water shock, which is a gasp of breath, followed by rapid breathing and high blood pressure. While this can be beneficial for some over a short time, it will become detrimental to everyone with time, so people should stay in a cold shower for no more than one minute.
It is especially dangerous for people with cardiovascular disease, aneurysms or heart problems and they therefore shouldn’t try it, Tipton says.
Other complications of cold water that could affect anyone include hypothermia and non-freezing cold injury, he warns, is damage to the small nerves and blood vessels of the hands and feet that can last for life.
The new free open-air saltwater pool is already proving popular.