Blood pressure drops excessive they sit or stand up which condition called or postural hypo-tension.Orthostatic hypotension which is also called postural hypotenmnsion.
Orthoostatic hypotension caan caused dizziness or lightheadedness hypotension which is a form of low blood pressure that can happens when standing after sitting or lying down.But in some cases people with high blood pressure may have a pounding feeling in their head or cheat a feeling of lightheartedness.
Dizziness and nausea people feeling lightheaded enough to faint or notice cold, clammy skin, blurry vision, or chest pain.Dizziness or light headedness when standing occurs in about 20% of old people.