What is considered a normal drop in blood pressure from standing to laying down? (Not laying to standing/orthostatic hypotension).

About 10 or less. when you lie down and your blood pools, your blood pressure should drop but no more than 10 mm of mercury. some argue however that a drop in blood pressure when you lie down is not pathological. why do you ask??
Unknown. The normal change in blood pressure from standing to supine has not been studied in the fairly recent past, except in a small study of pregnant women in third trimester.