Hydration may blunt cortisol response to stress, study finds

A study led by researchers at Liverpool John Moores University has found that people who habitually drink less than about 1.5 litres of water a day show a markedly stronger cortisol response to stress, even though they do not report feeling more thirsty than those who drink closer to recommended levels. In a laboratory stress test that mirrored real-world pressures, the low-hydration group exhibited significantly higher levels of the stress hormone, while both groups displayed similar increases in anxiety and heart rate. The findings suggest that maintaining adequate hydration could be an accessible means to help blunt daily stress responses and support long-term health.

The study recruited 32 healthy adults and divided them into two groups based on their regular fluid intake. One group consistently consumed less than 1.5 litres daily, while the other met or exceeded commonly recommended targets of about 2 litres for women and 2.5 litres for men. Hydration status was monitored for a week using standard measures, including urine characteristics and physiological samples. After this period, participants faced a controlled stress challenge that began with a surprise job interview...