Minute by minute – how the hot weather affects your body and the 10 signs you must never ignore

Scottish Sun

01-07-2025

Plus, how to stay safe during hot weather - from when to go outside to what to drink
HOT BOD Minute by minute – how the hot weather affects your body and the 10 signs you must never ignore
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BRITAIN is baking in glorious sunshine.
The Met Office predicts temperatures will hit 36C in parts of the UK today, after one of the hottest Junes on record, and sticky nights aren't offering much relief.
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Crowded beach in Lyme Regis, UK, yesterday
Credit: Alamy
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It's imperative to remember key sun safety, including drinking plenty of fluids and topping up sun screen
Credit: Getty
Most of England is currently subject to an amber heath health alert, meaning the entire population, the NHS, and transportation is likely to be affected by scorching temperatures.
This is because while the sunshine gives us a healthy hit of vitamin D we've all been dying for, the heat also brings a host of health risks we can't afford to ignore.
This could include a rise in deaths, particularly in people over 65 and those with existing health conditions, including respiratory and cardiovascular diseases.
There are also concerns over an increase in demand on health and care services, and overheated hospitals and care homes.
Experts say it can take as little as ten minutes to get sunburnt and 15 minutes to get heatstroke, in a worst case scenario.
Heatstroke happens when your body overheats so badly it can't cool itself down - and if left untreated, it can be deadly.
When the sun suddenly comes out in the UK, Brits are quick to get outside and lap up the rays.
It's imperative to remember key sun safety, including drinking plenty of fluids and topping up sun screen.
Here, experts reveal just how dangerous a hot weather can be, and how fast its effects could set in.
Under 10 minutes: SUNBURN
YOU might be fooled into thinking sunburn is only something that happens on holiday.
Don't take the risk, as sunburn can occur in under 10 minutes, even if you can't see it straight away.
Dr Kathryn Basford, of online doctors service ZAVA UK, told The Sun: 'You can very easily burn in as little as 10 minutes, if you're out in the sun and not properly protected from UV rays.
'It can also present itself through the course of the day and take between 24 to 72 hours to develop.'
Sunburn doesn't just cause sore and sometimes blistered skin, but affects your temperature regulation.
Prof Mike Tipton, Human and Applied Physiology, University of Portsmouth, told The Sun: 'Sunburn reduces sweating, which is an indirect problem in terms of impairing your thermo regulatory capabilities.'
How fast your skin reacts will depend on whether you are wearing any sun screen, your clothing, your complexion and how strong the UV rays are.
With every episode of sunburn, you increase the chances of skin cancer, as well as faster ageing skin.
15 minutes: HEAT EXHAUSTION
HEAT exhaustion is the illness that precedes heatstroke.
The symptoms include nausea, dizziness, muscle weakness, sweating, cool and clammy skin, irritability and confusion.
A key sign is body temperature going above 41C - this can happen within 10 to 15 minutes of being in hot weather, according to the Centre for Disease Control and Prevention.
Prof Tipton warned heat exhaustion is a particular risk for babies and small children.
He said: 'By putting people into warm baths, we can get their core temperature up by a degree and a half in 15 or 20 minutes. So you can get hot very quickly.
'If you're a small individual in a hot environment, particularly an environment with direct exposure to the sun, you're looking at heat related problems in 15 to 20 minutes.'
The 10 signs in the heat you should never ignore
If you're spending prolonged periods of time in the heat - then it's important to stay protected.
But, we are all human and sometimes we might forget to wear a hat or top up our suncream.
There are some clear warning signs you should never ignore - seeking shade and medical help if appropriate. Feeling off or out of sorts Nausea Dizziness Muscle weakness Sweating Cool and clammy skin Irritability and confusion Headache Thirst Loss of appetite
These could all be signs of heat stroke or heat exhaustion.
For adults, Prof Tipton said a dangerous increase in core temperature depends on a number of factors.
But in a hot and humid environment where someone is exercising, 'you'll be looking at getting your body temperature to a dangerous level in around 20 minutes,' he said.
Dr Basford said: 'Depending on how hot it is or how long you are in the sun, heat exhaustion can develop within a few minutes or gradually over several hours or days.
'It's important to cool down as soon as you notice any of these signs as heat exhaustion can develop into heatstroke if your body has become too hot and starts to lose water or salt.'
Minutes to hours: HEATSTROKE
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If not treated quickly, it can turn into heatstroke, which can be life threatening
Credit: Getty
HEAT exhaustion is not usually serious if you can cool down within 30 minutes, the NHS says, by going to a cool place, lying down and raising the feet, drinking water and cooling the skin.
But if someone does not feel any better after 30 minutes, you should call 999.
This is a sign they have heatstroke, which is when the body is unable to control its temperature.
The symptoms include hot and dry skin, difficulty walking, poor balance, confusion and disorientation and seizures (in severe cases).
Dr Basford said: 'Similar to heat exhaustion, heatstroke can develop within minutes or gradually over the course of several hours or days.
'While less common, heatstroke can be very serious if not addressed quickly."
30 minutes: DEHYDRATION
IT'S imperative to make sure you are getting enough fluids during the day, let alone during a heatwave.
Dehydration can be life-threatening, especially in the elderly, children and babies.
Dr Basford said: 'When you're out and about in the sun, it can take anywhere from 30 minutes to up to a few hours for the body to feel dehydrated.
'When exposed to the heat without properly hydrating your body, the water levels can fall low and you'll experience waves of fatigue, thirst, light-headedness and sometimes dizziness.
'Drinking water regularly can help you remain hydrated, as well as swerving those drinks that can dehydrate you further, like caffeine or alcohol.'
Dehydration can exacerbate, and contribute to, any of the heat illnesses described above.
Prof Tipton said: 'You need to sweat in order to maintain your body temperature, and that sweating is going to be impaired if you become dehydrated.'
Up to two days: DEATH
PROF Tipton said: 'Over the course of a heatwave, there'll be about 1,500 to 2,000 excess deaths, but very, very few of those deaths are caused by the direct effects of heating.
'The majority of people that die do so within the first couple of days of a heatwave.
'And the vast majority of those that die are over the age of 65 and their deaths are caused more by the stress that the heat puts on their cardiovascular system.'
When the body's core temperature reaches dangerous levels, this adds additional strain to what might be an already compromised cardiovascular system, heart and heart and blood vessels.
One of the other major causes of a heatwave related death is a blood clot, Prof Tipton said, as dehydration causes the blood to thicken.
This can happen to those with pre existing conditions, or even those who are reasonably healthy but, due to their age, don't have blood vessels as healthy as they once were.