Hi, I have a problem with feelig lightheaded in the mornings. I have found out I have low blood pressure when I first wakeup. I am also really thirsty and have to pee straight away, I figure I am dehydrated - which maybe causing the low blood pressure and the light headedness? (I have a big glass of water by my bedside). What could be causing me to get dehydrated every night (it's not alcohol). Have I got some hormone imbalence? My GP says my thryroid tests are normal, my calcium levels are normal I drink a lot during the day and pee a lot. I am also having palpitations, I have been referred to cardiology.