My blood pressure is quite low, the so-called low blood pressure type. Nevertheless, when I donate blood, my blood pressure can be so low that I cannot donate blood, and when I have a physical exam, it is a typical blood pressure reading. Apparently, my body does not want to be drained of blood, but does not want to be treated as unhealthy.
https://www.youtube.com/channel/UCJyb6vceAjGazPPGjJs-1Yw It has Japanese subtitles, so I think it'll be useful