I am 13 I have almost passed out twice in less than a week.. Once on the fourth and once yesterday on the sixth. On the fourth I had been standing outside in a line for a carnival ride. I got really dizzy and everything went bright but luckily my sister got me water and I drank a bit and was fine after, just needed a bit of rest. Yesterday I had been at the pool and my sister and I had been tanning outside and got up and walked over to another table. That s when it happened again.. Not as powerful as it was on the fourth but still. My sister was there to get me water and I felt better once again. I have pretty much the same diet as my sister and this doesn t happen to her.. Could I just be dehydrated? Or could this be something serious? I m worried this will happen again.