At a glance
- Low hydration heightens stress response: People who drank less than 1.5 litres of fluid a day showed cortisol levels over 50% higher under stress than those who stayed well-hydrated.
- Dehydration activates stress hormones: Reduced fluid intake triggers vasopressin, which conserves water but also increases cortisol, linking poor hydration to long-term health risks like heart disease and depression.
- Simple prevention strategy: Staying hydrated, even by keeping a water bottle nearby — may help the body manage stress more effectively and support overall well-being.
A new study from Liverpool John Moores University (LJMU) suggests that drinking too little water could make people more vulnerable to stress-related health problems such as heart disease, diabetes, and depression.
Published in the Journal of Applied Physiology, the research found that people who drank less than 1.5 litres of fluid a day, roughly seven cups of tea, had a cortisol response to stress more than 50% higher than those who met recommended daily intake levels.
Study lead Professor Neil Walsh, a physiologist in LJMU’s School of Sport and Exercise Sciences, 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.” He added:
“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.”
The project, funded by Danone R&I, divided healthy young adults into two groups: those who drank less than 1.5 litres of fluid daily and those who met recommendations of 2 litres for women and 2.5 litres for men. Both groups were matched for factors that can influence stress, including sleep and psychological characteristics.
After a week of maintaining their usual drinking habits, participants underwent the Trier Social Stress Test, which simulates real-world stress through a mock interview and mental arithmetic task. Dr Daniel Kashi, a member of the research team, said: “Both groups felt equally anxious and experienced similar increases in heart rate during the stress test. However, only the ‘low fluid’ group showed a significant increase in saliva cortisol in response to the stress test.”
He continued: “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. 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 study explains that dehydration triggers the release of vasopressin, a hormone that helps the body retain water but also activates the brain’s stress-response centre, increasing cortisol production. Sustained vasopressin release can strain the kidneys and heighten stress responses.
The researchers conclude that staying hydrated could help the body manage stress more effectively. “Being hydrated may help your body manage stress more effectively,” said Dr Kashi. He advised that a simple way to check hydration is by monitoring urine colour, light yellow typically indicates good hydration.
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The post Why Drinking Enough Water Could Protect You from Stress-Related Illness first appeared on MQ Mental Health Research.