If your brain doesn’t seem to be operating at full throttle lately, maybe all you need is a tall glass of water. Researchers at the University of Connecticut’s Human Performance Laboratory asked 25 young, healthy women to walk on a treadmill to induce dehydration, then take a series of cognitive tests to measure concentration, reasoning, memory, learning, reaction time and vigilance. They then compared test scores with those of a separate set of tests the individuals were asked to perform while not dehydrated.
The results were clear: in mild states of dehydration (an approximately 1.5% loss in normal water volume), the women struggled with fatigue, headaches and difficulty concentrating. Even when they were able to think clearly they perceived cognitive tasks to be difficult, indicating a mood shift. Another study involving men yielded a similar outcome.
Study co-author and physiology professor Lawrence E. Armstrong says the study is evidence that it’s best to not wait for thirst to kick in before having a beverage because by then the mind and body are already being affected by dehydration. The full study can be viewed on the Journal of Nutrition website at jm.nutrition.org.