25/09/2025
๐๐๐๐ฌ๐๐ฅ๐๐ง๐๐ข๐ก ๐ฆ๐๐๐ฅ๐๐ง๐๐ฌ ๐๐จ๐๐๐ฆ ๐๐ก๐ซ๐๐๐ง๐ฌ ๐๐ก๐ ๐ฆ๐ง๐ฅ๐๐ฆ๐ฆ
On September 23, 2025, researchers from Liverpool John Moores University (LJMU) published a study showing how something as simple as dehydration can silently fuel stress, anxiety, and long-term health problems.
For years, scientists have linked stress to increased risks of heart disease, diabetes, and depression. But this new research, published in the Journal of Applied Physiology, reveals that not drinking enough fluids can worsen the bodyโs stress response, even without making people feel thirstier.
The study divided healthy young adults into two groups: those who typically consumed less than 1.5 liters of fluid daily (about seven cups of tea), and those who regularly met fluid intake recommendations, 2 liters per day for women, 2.5 liters for men. Both groups were otherwise similar in psychological traits, sleep habits, and health factors.
Over one week, participants followed their usual drinking habits while researchers tracked hydration levels in blood and urine samples. Then, each participant underwent the Trier Social Stress Test, a mock job interview and math challenge widely used to simulate real-world stress.
The results were striking. While both groups felt equally anxious and had similar rises in heart rate, the low-fluid group showed a cortisol response over 50% higher than those who were well hydrated. Cortisol, the bodyโs main stress hormone, is known to increase risks of chronic diseases when levels are repeatedly elevated.
Even more concerning, the under-hydrated group didnโt feel thirstier, but their darker, concentrated urine revealed biological strain. According to Dr. Daniel Kashi, a physiologist at LJMU, โPoor hydration was associated with greater cortisol reactivity to the stress test. Exaggerated cortisol reactivity has been linked to poor long-term health.โ
The mechanism behind this effect lies in vasopressin, a hormone released when the body senses dehydration. Vasopressin conserves water by acting on the kidneys but also signals the brainโs stress center, boosting cortisol release. Over time, this dual action can place strain on both the kidneys and the stress-response system.
Professor Neil Walsh, the studyโs lead, emphasized: โCortisol is the bodyโs primary stress hormone and exaggerated cortisol reactivity is associated with heart disease, diabetes, and depression. Keeping a water bottle close could be a simple habit with lasting benefits.โ
The findings, supported by Danone R&I, reinforce global hydration guidelines. Practical advice is simple: check your urine colorm, light yellow suggests good hydration. Whether preparing for a deadline, exam, or speech, maintaining hydration could help your body cope with stress and protect long-term health.
Journal Reference:
Daniel S. Kashi, Marianne Hunter, Jason P. Edwards, Juliane Zemdegs, Jennifer Lourenรงo, Anne-Cรฉcile Mille, Erica T. Perrier, Alberto Dolci, Neil P. Walsh. Habitual fluid intake and hydration status influence cortisol reactivity to acute psychosocial stress. Journal of Applied Physiology, 2025.
Read more: https://journals.physiology.org/doi/full/10.1152/japplphysiol.00408.2025