Miranda Kerr swears by a daily cold shower to keep her skin glowing. Fearne Cotton endures an icy blast each day as a way to boost her energy and her mood. The BBC’s Dr Michael Mosley is so convinced by evidence linking cold water immersion to improved immunity and heart health, he’s now a regular cold water swimmer.
Whether it’s a dip in the sea, a dunk in an ice bath or just a quick burst of chilly water at the end of a warm shower, cold water therapy has taken the wellbeing industry by storm. Its proponents believe it’s beneficial as it can help harness the body’s natural response to stress.
While repeated exposure to stress in high doses can clearly be toxic, lower doses encourage beneficial adaptations that actually enhance health. In fact, a growing body of research suggests that the short-term stress of cold water immersion triggers a raft of whole body benefits that can boost circulation, reduce muscle inflammation and improve mood.
Immersing yourself in cold water causes your heart rate to increase and your blood vessels to change shape - some decrease in size, while others double, and all in a matter of seconds. Dr Mosley calls this, “an orchestra of responses that put your body into gear for survival – all the while, giving you quite the thrill!”
And while the practice has only recently been embraced by celebrities, it appears our ancestors were well ahead of us when it came to using cold water for health purposes. The Romans used a combination of steam rooms, hot tubs, and cold baths, while Victorian doctors prescribed cold baths for both bruises and hysteria. Traditional Chinese medicine (TCM) has a long tradition in promoting health by taking a dip in pools, rivers or lakes where the water temperature is usually below 20℃.
So were the health practitioners of the past really on to something? We’ve delved into the science behind the headlines to find out if braving the cold is really worth the goosebumps...
1. Cold showers can boost your mood
A morning blast of cold water is undoubtedly invigorating - and you’ll certainly feel happier once it’s over. But could a daily cold shower be such an effective way to improve our moods it could even help treat depression? That’s what researchers at the Virginia Commonwealth University School of Medicine aimed to find out.
They hypothosised that the skin has a high density of cold receptors. When these are stimulated, it sends strong electrical impulses to your brain to trigger the release of mood-regulating neurotransmitters like endorphins (the same chemicals that create the famous “runner’s high”).
Although they only tested their theory on patients with low mood, they showed that cold hydrotherapy “can relieve depressive symptoms rather effectively”, with no noticeable side effects.
A narrative study on the benefits of cold water therapy as a treatment for low mood was carried out on a 24-year old patient with depression and anxiety. She had previously not responded to conventional treatment and was searching for alternative therapies.
She started a weekly programme involving cold water swimming, which resulted in an immediate improvement in mood after each swim and a sustained and gradual reduction in the symptoms of depression overall.
The intervention ultimately led to a reduction in the patient’s medication use and, after one year of therapy with cold water swimming, she was medication-free.
2. Cold showers can make you feel more alert
If waking up feels like the hardest thing you do all day, you could be particularly sensitive to sleep inertia. Although it’s a normal part of the brain’s transition between sleep and wakefulness it slows down your motor and cognitive skills and, for some people, this morning grogginess can last up to an hour.
But turning down the dial in your morning shower stimulates catecholamines - hormones that the body produces in response to emotional or physical stress. This helps activate the sympathetic nervous system and increases the concentration of norepinephrine and β-endorphin so you’re ready to fire on all cylinders again.
3. Cold water swimming may improve blood sugar management
In Type 2 diabetes, the level of sugar in the blood becomes too high. Figures from Diabetes UK show that almost 4.4 million people have the condition in the UK, and that there are an additional 850,000 living with type 2 diabetes who are yet to be diagnosed.
Research has consistently shown that for some people, combined lifestyle interventions - including diet, physical activity and sustained weight loss - can be effective in reducing the risk of type 2 diabetes by about 50%. And could cold water therapy also become a recommended treatment?
In a study that looked at the effects of cold water therapy on blood glucose control, swimming in cool water was found to hinder the development of type 2 diabetes and improve management of the condition, although the most beneficial effects were seen predominantly in the female swimmers.
In the field study, 30 cold water swimmers were examined for six months with regard to body composition and insulin sensitivity. For female swimmers with lower body fat percentage, there was an increased insulin sensitivity as well as a reduction in insulin secretion and resistance.
So how does it work? Researchers from Canada attempted to find out. Their report, published in the medical journal Physiology of Thermal Therapy found that cold exposure not only increases energy expenditure, but it also aids whole body glucose and fatty acid utilization. Much of the metabolic effects were attributed to the effects of shivering on skeletal muscles, but they also discovered repeated exposures to cold can lower fasting glucose and insulin levels and improve dietary fatty acid handling.
4. Cold water therapy can support your immunity
Submerging yourself in cold water in the depths of winter sounds counter-intuitive, but there is growing evidence that winter swimmers are more resistant to certain illnesses and infections. For example, cold water swimmers seem to have fewer upper respiratory tract infections.
And the good news is that you may not even have to brave the sea to reap the immunity benefits. One study has found a link between cold showers and boosted health, showing a 29% reduction in reported “sick days” at work for those who submitted themselves to the daily ritual.
The effects of cold water on the immune system have been studied widely. Cold water helps to boost the white blood cell count because the body is forced to react to changing conditions. Over time, your body becomes better at activating its defences.
Research was carried out on 15 healthy men who had never been exposed to cold water swimming. They were studied for five consecutive months of winter swimming. Findings showed significant changes in hemoglobin concentration, the number of red blood cells, the hematocrit index and mean corpuscular volume of red blood cells and the percentage of monocytes and granulocytes after the winter swimming season. The obtained results may indicate positive adaptive changes in the antioxidant system of healthy winter-swimmers. These changes seem to increase the readiness of the human body to stress factors.
Research has also found changes in uric acid and glutathione (antioxidant) levels during ice bathing. Further investigation demonstrated that the intensive voluntary short term cold exposure of winter swimmers produces oxidative stress, improving antioxidant adaptation.
5. A cold shower can improve exercise recovery
Ever wondered why top athletes swear by an ice bath after long periods of exertion? Cold water helps constrict the blood vessels near the surface of your skin - a process known as vasoconstriction - diverting blood towards your core. This is said to reduce swelling and inflammation in the muscles, by drawing waste substances and lactic acid away.
Then, when the body begins to warm up again, vasodilation occurs, pumping fresh, warm blood around the tissues, bringing nutrients, oxygen, and aiding in recovery.
6. A cold shower could help you build muscle
Need another reason to turn down the heat on your post-workout shower? It’s been suggested that swapping hot for cold water could help you see more muscle gains. Although further research is required into this area, a 2015 study found that cold water immersion attenuated long term gains in muscle mass and strength. It also blunted the activation of key proteins and satellite cells in skeletal muscle up to two days after strength exercise
7. Cold water can help soothe inflammation
Chronic inflammation is at the root of many of the diseases that represent the leading cause of mortality worldwide, such as heart disease, diabetes, stroke and cancer. But, one particularly exciting area of research is looking at how cold habituation decreases inflammatory responses over time.
Cold showers activate your sympathetic nervous system, lowering levels of the pro-inflammatory cytokines that contribute to chronic inflammation.
Where to start
Ready to take the plunge yourself? Luckily you don’t have to head for the sea or take an ice bath to reap the benefits, as a shower that’s 21℃ or cooler is quite adequate. Start gradually by taking a warm to cold shower, alternating to cold for just a few seconds. Keep your breathing steady and, as you get used to the feeling (which isn’t pleasant at first!), you can gradually increase your time in the cold water.
If you enjoyed this post, you may like to read “Healthy habits of successful people”.