A study has been conducted by experts at Liverpool John Moores University
You could be making your stress levels worse by not drinking enough water, a new study has revealed. The research found that those who don’t drink enough water have a higher biological response to stress, releasing more of the stress hormone cortisol, even though they don’t feel any thirstier than those who drink more.
So, keeping a water bottle close by during stressful times could be a simple way to improve your long-term health, according to the researchers. The study was conducted by experts at Liverpool John Moores University (LJMU) and involved 16 participants who drank less than 1.5 litres of water a day, as well as 16 others who regularly hit the daily recommended fluid intake.
The team used guidelines from the European Food Safety Authority (EFSA), which suggest men should drink 2.5 litres of water a day and women should aim for two litres. Meanwhile, in the UK, the Eatwell Guide recommends adults should consume between six and eight cups of fluid a day, equating to roughly 1.5 to two litres.
However, it’s worth noting that people may need to up their water intake when the weather is hot, if they’re particularly active, recovering from an illness, or if they’re pregnant or breastfeeding. The researchers kept track of hydration levels in both groups over a week using urine and blood samples, before inviting them into the lab for a stress test.
The experiment featured a surprise job interview, with participants given just 10 minutes to get ready, reports Bristol Live. They were then ushered into another room where a mock camera had been positioned and told to face a panel of three individuals wearing white coats for the bogus interview.
After the fake interview concluded, participants were put through a mental maths test that required them to subtract figures as quickly as possible. Professor Neil Walsh, from LJMU’s School of Sport and Exercise Sciences, branded the examination as “really flustering”.
Speaking to the PA news agency, he said: “We know that people who have a low daily fluid intake, who don’t meet the recommendations, are likely to be poorly hydrated. But what we didn’t know was whether, when you then stress those people under controlled conditions, they would have a greater stress hormone response.”
Scientists gathered saliva specimens from participants both before and after the stress examination to assess cortisol concentrations. Cortisol, dubbed the stress hormone, gets released by the adrenal glands when under pressure and also influences immune function, metabolism and blood pressure.
The research team discovered cortisol concentrations were elevated in those consuming less fluid. Prof Shaw observed that stress reactions including accelerated heart rate, clammy palms and parched mouth remained comparable across both groups. “Both groups felt equally anxious and experienced similar increases in heart rate during the stress test,” he said.
“But the people who were poorly hydrated, because they were not drinking enough water each day, had much greater cortisol responses.” The low-fluid intake group did also not report feeling more thirsty than those who drank more, according to Prof Walsh. He added: “Cortisol is the body’s primary stress hormone and exaggerated cortisol reactivity to stress is associated with an increased risk of heart disease, diabetes and depression.
“If you know you have a looming deadline or a speech to make, keeping a water bottle close could be a good habit with potential benefits for your long-term health.” Prof Walsh said further research is needed to better understand the findings, published in the Journal of Applied Physiology, and to see if increasing water intake in those who do not drink enough can reduce responses to daily “micro stressors” like traffic jams or presentations at work.
“We’d like to think that meeting the water intake guidelines could be one of a number of things you could do to blunt that cortisol response day to day,” he added.