Stressed? Here’s why drinking some water can help

Most people know they should drink more water, but our new research reveals an unexpected consequence of falling short: it could be making everyday stress significantly harder to handle.

Our study, published in the Journal of Applied Physiology, found that people who drank less than 1.5 litres daily showed dramatically higher levels of cortisol – the body’s primary stress hormone – when faced with stressful situations. The finding suggests that chronic mild dehydration may amplify stress responses in ways we’re only beginning to understand.

We tested healthy young adults by dividing them into two groups based on their usual fluid intake. One group drank less than 1.5 litres daily, while the other exceeded standard recommendations of roughly two litres for women and 2.5 litres for men. After maintaining these patterns for a week, participants faced a laboratory stress test involving public speaking and mental arithmetic.

Both groups felt equally nervous and showed similar heart rate increases. But the low-fluid group experienced a much more pronounced cortisol surge – a response that could prove problematic if repeated daily over months or years. Chronic elevation of cortisol has been linked to increased risks of heart disease, kidney problems and diabetes.

Surprisingly, the under-hydrated participants didn’t report feeling thirstier than their well-hydrated counterparts. Their bodies,...

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