Researchers from John Moore's University in Liverpool discovered that those who drank less water had a stronger stress response in their bodies. Specifically, they showed higher levels of cortisol, a stress hormone, when put in stressful situations.
Study lead Professor Neil Walsh from Liverpool John Moores University explained, "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."
To explore the link between water consumption and stress level, the study involved 32 volunteers. Half were limited to 1.5 liters of water a day, while the other half drank the recommended amount - 2.5 liters for men and just over 2 liters for women.
After providing urine and blood samples, the participants faced a stress test that included a surprise interview and a fast-paced math task.
Saliva tests showed that cortisol levels rose much faster in people who drank less water. This means even mild dehydration can over-activate the body's stress system, which may harm health over time.
Interestingly, physical signs of stress like a faster heartbeat, sweaty palms, and dry mouth were similar in both groups. People who drank less water also didn't report feeling thirstier.
"Although the low fluid group did not report being thirstier than the high fluid group, they had darker and more concentrated urine, clear signs of poor hydration," study author Daniel Kashi noted.
"An important observation was that poor hydration was associated with greater cortisol reactivity to the stress test. Exaggerated cortisol reactivity to stress has been associated with poor long-term health."
The researchers said that more studies are needed to see if drinking enough water can reduce stress responses in everyday life.
"Being hydrated may help your body manage stress more effectively," Dr. Kashi advised.
"If you know, for example, that you have a stressful schedule, maybe 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."
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