Overview

• Researchers at Liverpool John Moores University reported in the Journal of Applied Physiology that adults drinking under about 1.5 litres daily showed more than a 50% greater cortisol response during the Trier Social Stress Test.
• The study screened 62 healthy volunteers and tested 32 split evenly into low- and higher-intake groups after seven days of monitored usual fluid consumption.
• Participants with lower intake did not report greater thirst yet produced darker, more concentrated urine, indicating thirst may be an unreliable cue for hydration status.
• Authors propose dehydration-driven vasopressin as a possible mechanism for heightened stress reactivity and caution that the small, short-term design cannot prove causation.
• Coverage cited NHS guidance of six to eight drinks a day and highlighted GP-reported risks of dehydration, including fatigue, cognitive decline, electrolyte imbalance, kidney stones and UTIs, low blood pressure, and skin changes.