One of my co-workers was telling me about her sister who has one of those low blood pressure conditions. It's called orthostatic intolerance.
It's different than just regular orthostasis. Instead of getting dizzy from low blood pressure just when you stand up, it hits you a few minutes later.
She says a few minutes after her sister gets up, she sometimes feels dizzy, tired, her eyes aren't focused, and she feels light headed. The doctor has told her that there's some problem with the low blood pressure that causes blood to flow down to her legs and stay there. She might start taking some medicine for it, but she doesn't really want to.