As the relentless heatwave continues, many might be tempted to jump into a cold shower to lower their body temperature. However, experts have warned that a chilly rinse may not actually help you cool off at all, and that bathing in lukewarm water is actually more effective.
The Science Behind Cooling Down
Adam Taylor, a Professor of Anatomy at Lancaster University, explained that it all comes down to how our blood vessels react to changes in temperature. 'Although diving into a cold bath or shower straight after being out in the heat might feel nice on your skin, it isn't doing what is needed to reduce the core temperature of the body,' Professor Taylor wrote on The Conversation.
Our body's optimal temperature is around 37°C. When our core gets too hot, several mechanisms kick into place to help us cool down. One important response is the dilation of blood vessels, allowing more blood to get closer to the relatively cooler surface of the skin.
'When exposed to cold, the blood vessels near the skin constrict, reducing the blood flow into these areas,' Professor Taylor said. 'Basically, you're tricking your body that it doesn't need to cool down, but actually needs to conserve heat. This will hold the heat in and around your organs instead of getting rid of it.'
Record Heat in the UK
This advice comes as the UK's hottest May day record was broken for a second day in a row this week. Kew Gardens in south-west London recorded a provisional temperature of 35.1°C yesterday, beating Monday's 34.8°C record-high in the same place. While such temperatures may feel pleasant on holiday, they can quickly become unbearable in the UK, as infrastructure and buildings were historically designed to retain warmth.
As a result, many people have turned to ice baths or cold water plunges in a bid to cool off. However, sudden exposure to very cold temperatures could even trigger dangerous consequences for some individuals, Professor Taylor warned.
Risks of Cold Water Exposure
Submerging yourself in water that is 15°C or under can trigger the cold shock response, which causes the blood vessels in the skin to constrict rapidly. This increases blood pressure and can be particularly dangerous for people with underlying heart conditions such as coronary artery disease.
'Thankfully, these events are rare and probably won't happen if you're just taking a cold shower or bath in your home,' he said. 'But you might want to skip the cold plunge or avoid taking an ice bath on a hot day for this reason.'
What Works Best?
While cold showers are not advised, hot showers are also not the way forward on a warm day. Water that is warmer than the body will transfer heat to the body, potentially increasing its core temperature. A tepid or lukewarm bath or shower, at 26-27°C, is most effective, scientists say.
Another reason to skip a cold shower on a hot day is that it might not get you fully clean. Cold water has been shown to be less effective at removing and breaking down sebum and bacteria on the skin compared to warmer water. This means that body odour could persist, and trapped dirt within pores could lead to blackheads, whiteheads and acne. Warm or lukewarm water, however, can help dissolve and loosen material in the pores.
Additional Tips for Staying Cool
- Stay hydrated by drinking plenty of water.
- Use fans or air conditioning if available.
- Wear lightweight, light-coloured clothing.
- Avoid strenuous activities during peak heat hours.
Experts have warned that climate change is making UK heatwaves more frequent, more intense, and longer lasting. As temperatures rise, it is important to adopt safe and effective methods to stay cool.
