Hello, I am a 24 year old female and lately I noticed my heart rate increases a lot when standing up or walking casually. When I am laying down my heart rate is around 65 bpm and when I stand up and start walking around the house it goes to 150-160 bpm. When I go out and walk for about 10 mins I start getting really sweaty and feel hot, and sometimes I m completely out of breath. Ive been told couple years ago by my GP that my blood pressure drops when I stand up. Could this be heart failure, or Postural Orthostatic Tachycardia Syndrome? Also in the past year I ve been very sedentary because of my college work, with most days not leaving the house or only walking for shorts periods of time. Is it something wrong with my heart or I m just very unfit, due to a very inactive lifestyle for the past year?