"Eight by eight -- eight 8-ounce glasses a day -- is a good general rule of thumb," This is actually a myth.that this is the magic amount for everyone, because there are so many variables. The "right" amount for you depends on factors including your age, your activity level, your health level, medications you're taking, and the weather. So how do you know if you're drinking enough? Follow your thirst, and know that you're on the right track if you have light lemonade colored urine!
Being sure to sip water throughout a stressful day can soothe stress-induced symptoms as diverse as headaches, tense muscles, fuzzy thinking, a pounding heart, and low energy. That's because stress taxes all your basic body systems -- and when you're dehydrated, the effects are magnified.
Given that more than half your body weight is water, just a 2-percent reduction in hydration has a dramatic impact on energy levels and cognitive function. And dehydration further raises levels of cortisol -- the "stress hormone."