8 Surprise Reasons You're Still Tired

You Forgot Your Water Bottle at Home

Even mild dehydration (1.36 percent loss of normal water volume in the body) can slow your mental gears and make you feel woozy, concluded the authors of a study published last year in the Journal of Nutrition. But the sensation of thirst doesn't usually kick in until you're about 1 or 2 percent dehydrated, so a dry mouth isn't a reliable gauge. In addition to drinking plenty of water, you can stay hydrated by snacking on raw fruit and vegetables, yogurt or soup.