When you're dehydrated your blood pressure drops, heart rate increases, blood flow to the brain slows -- all of which can make you tired. Luga Podesta More Quotes by Luga Podesta More Quotes From Luga Podesta Neurological effects of dehydration can cause irritability. Luga Podesta top-news This occurs because your body starts to limit blood flow to the skin. Luga Podesta top-news