Most days when i stand, my heart goes up to about 90 - 95 the slows after a few mins. a day after panic attack it beats about 70 - 72 bpm standing and feels more forceful and uncomfortable. sometimes i feel light and unsteady. why does this happen?

Normal Response: When you stand, blood rushed to your feet and your body will do a few things to help get the blood circulating back to your heart, brain and the rest of your body. Initially your heart rate will increase and blood vessels will constrict, in addition your heart will beat a bit more forcefully. Once your body acclimates these reflexes will scale back a bit.