If your head is below your heart before you get up, all the blood stores in there because your brain absorbs alot of blood with all the vains around it. If you stand up too quickly it might drain down and make you feel lightheaded.
First. No symptoms without proper information. Do you eat proper, do you get enough sleep. Do you drink enough water. Do you exercise enough. Are you a runner. Isyour nose runny. Must answer all these and more. Or go tell it to doctor he know. We just through thoughts at you you silly. Love ya.