This is what it's called.
Best answer:
It's a phenomenon called "orthostatic hypo tension". This happens as when you stretch you're demanding that the blood leaves where it is and goes to where it's needed. When you're sitting and relaxing your blood pressure settles at a "normal" range of about 120/80. When you stand up suddenly, or stretch suddenly, your blood is needed at the organs that you are demanding, or when you stand up, your blood rushes to the bottom (laws of gravity) of your body, therefore your blood pressure goes WAYYY down very quickly. What causes the dizziness is the blood suddenly leaves your brain and goes to the part of the body that it's needed for that second . You'll find, though, that after you've been standing for a second or two, or after you're done stretching, your blood pressure will settle again.
Happy stretching!!
