We do it when we’re hot, anxious or embarrassed … and sometimes feel more anxious and embarrassed as a result. Time to get cool about sweating …
Summertime and while iced drinks, shady retreats or a dip in the sea can take the heat off, most of us tend to feel a bit stickier as temperatures rise. Not a great sensation perhaps, but one that’s vital for our wellbeing.
So why, if sweating is essential, is it also problematic and can even carry something of a stigma? We certainly have a complicated relationship with sweat, one of our least understood secretions, says author Sarah Everts in a fascinating new book, The Joy of Sweat.
While perspiration is fine as evidence of a work out or a run, wet patches sabotaging a crisp professional look or even an attempt to feign indifference to a secret crush is, well, the pits. Then there’s body odour. We spend fortunes on perfumes, deodorants and antiperspirants, but often pay tidy sums to sweat it out in gyms, saunas and steam rooms.
There are also unlucky souls who suffer from excessive sweating, a condition called hyperhidrosis. This is thought to affect 1% of the population though the true figure is at least double that as many people don’t seek help according to Dr Adil Sheraz, consultant dermatologist at the Royal Free Hospital, London.
Everyone’s sweat is unique, making it an ideal ID tracker in criminal investigations but also, potentially, a biomarker to reveal aspects of our health says leading expert Simona Francese, Professor of Forensics at Sheffield Hallam University.
Understanding sweat cannot only de-stigmatise a natural function, but help us be more supportive those with a problem. Plus, importantly, a little sweat know how will help us manage extreme temperatures better in an age of climate change.
Our core temperature needs to be kept stable at around 37.5 C and sweating is the body’s main thermostat regulating mechanism. As sweat evaporates from our skin it has a cooling effect, which is why we feel cold stepping out of the shower.
We are born with the three to the four million sweat glands we’ll have for life and while the eccrine glands, found all over the body, work from birth releasing salty water when we get too hot, the apocrine glands found in areas with hair follicles such as armpits, only become active in puberty.
Anxiety, stress or fear trigger the fight or flight hormones adrenaline and noradrenaline that activate both sets of sweat producing glands. More pleasurably, so does becoming sexually aroused.
While apocrine gland sweat doesn’t smell, it contains fatty acids, lipids and other substances that the naturally occurring bacteria present on our skin feed on, and it’s that process that is responsible for body odour which tends to make us recoil or feel ashamed.
Washing removes the bacteria which are also destroyed by antiseptic contained in many deodorants. Antiperspirants work in a different way, containing aluminium which blocks sweat pores.
There have been questions over the safety of aluminium, widely used in other cosmetic products, but two years ago the European Union’s Scientific Committee on Consumer Safety (SCCS) gave it the green light at specified levels. Further, Cancer Research UK says there is no good evidence to suggest a link with cancer while the Alzheimer’s Society’s verdict is that there is no convincing relationship to the development of Alzheimer’s .
Why our sweat baseline differs is largely thought to be genetic but also depends on where we grew up as sweat glands acclimatize to different environments. Size also makes a difference as being overweight produces more body heat.
People who always seem cool and collected and, more specifically, dry in hot weather are still sweating. It’s just their bodies are doing so very efficiently, releasing just enough sweat for optimum cooling evaporation but not so much as to drip.
Hot flushes during menopause that can see us drenched in sweat (tips box t/c) are due to low oestrogen which disrupts the body’s temperate control. About 80% of women experience them to some degree but they disappear post menopause. In fact, as we get older we tend to sweat less in general as the sweat glands shrink.
Excessive sweating can be due to hyperhidrosis, a condition thought to be genetic though the cause isn’t really known according to dermatologist Dr Sherez.
‘Living with hyperhidrosis can be debilitating and have a significant impact on the quality of life,’ says Dr Sherez, who welcomes greater understanding and awareness.
‘About 90% of people with the condition have primary hyperhidrosis which usually develops during childhood or soon after puberty and often affects one or more areas, for example, face and head, feet, hands or underarms.’
The condition can mean the palms of the hands become so sweaty it’s hard to hold a pen or avoid leaving marks on paper, adding to exam stress for teenagers affected.
Secondary hyperhidrosis affects a more generalised area and occurs as a reaction to medication or another underlying medical condition. While primary hyperhidrosis switches off at night, secondary hyperhidrosis does not.
Antiperspirants can be used on specific areas, and stronger versions can be prescribed although there is a risk of irritation. If feet are particularly affected, changing socks that absorbs moisture twice a day, leather shoes and different shoes day to day are basic measures
See your GP if nothing helps, it lasts for more than six months, interferes with daily activities, you have a family history of excessive sweating or you are taking medication for another condition advises Dr Sherez. If the problem is severe your GP may refer you to a dermatologist.
Treatment may involve tablets to reduce sweating, treating the area by passing a weak electrical current through water (iontophoresis), botox though this may not be available on the NHS or in, extreme cases, surgery to remove the sweat glands.
Sweat prints have been used in criminal investigations and are also a potential biomarker to reveal aspects of our health according to leading expert Simona Francese, Professor of Forensics at Sheffield Hallam University.
Currently only cystic fibrosis (CF) uses a sweat test as a standard diagnostic tool though. Measuring levels of chloride, as salt, in the sweat of new-born babies helps make or exclude a diagnosis when there is a family history or possibility of CF (cysticfibrosis.org.uk)
Other conditions under research where sweat may be a useful future diagnostic aid include tuberculosis (TB), the skin condition psoriasis, Parkinson’s disease, diabetes and kidney function. Meanwhile there’s huge commercial interest in developing an application for sweat as a biomarker alongside heart rate, steps and more in personalised trackers.
‘Molecules are the storytellers of who we are and what we’ve been up,’ to says Simona Francese. ‘We just need the right technology to make them talk.’
The Joy of Sweat (Norton) by Sarah Everts is out now.
To keep sweating and maintain our body temperature we need to avoid becoming dehydrated. The average adult requires between 1.5 to two litres of fluid a day but everyone differs according to dietician Claire Fudge, spokesperson for the British Association of UK Dieticians (bda.uk.com) and director of Nutricise Ltd.
‘Thirst is usually an indicator we need more fluid but salty food, alcohol and hormones activated when we’re stressed can make us feel thirsty too,’ says Claire.
Babies, children and the elderly are more at risk of dehydration but medications may also cause a dry mouth so check the accompanying leaflet or ask your pharmacist.
The colour of your pee is a clue to your level of hydration. It shouldn’t be as dark as it is first thing in the morning advises Claire but cautions that what we eat and drink also influences the colour (ie beetroot, Vitamin C).
Don’t like drinking water? Tea, coffee, milk and fruit juice are fine but be aware of the caffeine, calorie and sugar content. Milk and fruit juice actually have better hydrating properties than water according to the Beverage Hydration Index (BHI), as the ingredients cause us to retain more fluid Claire explains.
It’s often thought that excess sweating may mean we need extra salt but this is unlikely unless you are a professional athlete. ‘If you’re doing strenuous exercise somewhere hot and sweating a lot you might want to consider taking an oral rehydration or electrolyte solution,’ suggest Claire. ‘It’s also possible to become dehydrated when it’s very cold as we may drink less.’
Symptoms of heat exhaustion include headache, dizziness, sweating and pale clammy skin, a temperature of 38C or above and thirst. It is not usually serious if you can cool down within 30 minutes advises the NHS, but if it turns into heatstroke, treat as a medical emergency and call 999. Symptoms of heatstroke include feeling unwell after 30 minutes resting in a cool place and drinking plenty of water, not sweating even while feeling too hot, a temperature of 40C or above, confusion, a fit or loss of consciousness. See nhs.uk/conditions/heat-exhaustion-heat-stroke
Men sweat and women only glow is the old adage but scientists say there’s little evidence to support major sex differences in sweating.