According to study researchers “most people only think about drinking water when they are thirsty; but by then it may already be too late. Even mild dehydration can alter a person’s mood, energy level and ability to think clearly. The tests showed that it didn’t matter if a person had just walked for 40 minutes on a treadmill or was sitting at rest – the adverse effects of mild dehydration were the same. Mild dehydration is defined as an approximately 1.5 percent loss in normal water volume in the body.”
Keep in mind that you don’t feel thirsty until you’re 1 or 2 percent dehydrated. By then it’s already affecting your mind and body performance.
The researchers evaluated vigilance, concentration, reaction time, learning, memory and reasoning. According to the study, mild dehydration causes headaches, fatigue and difficulty concentrating in young women. Participants also perceived tasks as more difficult when slightly dehydrated, although there was no substantive reduction in their cognitive abilities.
In men, mild dehydration caused some difficulty with mental tasks, particularly in the areas of vigilance and working memory. Additionally, young men experienced fatigue, tension and anxiety when mildly dehydrated.
In order to stay properly hydrated, experts recommend that individuals drink eight 8-ounce glasses of water a day, which is equivalent to about 2 liters of water. Also, you can get water from eating lots of vegetables and fruit. “People can check their hydration status by monitoring the color of their urine. Urine should be a very pale yellow in individuals who are properly hydrated. Urine that is dark yellow or tan in color indicates greater dehydration.”