Not sure where to post this but anyways...I find myself being not as mentally sharp, and find it harder to focus, concentrate, think about things etc. I notice this many times when I wake up, and throughout the day. However, if I have a meal, or drink a glass of water, this dull feeling is gone and I feel fine again. But about 30-45 minutes later, I notice it coming back again. Is this a dehydration problem? I currently don't exercise or take vitamins.