Why have I had sudden heart rate increase?

Alright so more detail: I can increase my heart rate somehow. It doesn't involve holding my breath or thinking about anything. Somehow I can just increase my heart rate, it feels like I'm tapping into my adrenal glands or something because my eyes dilate...

I notice that when I bend down or just do something very little my heart rate will increase a lot. I thought it might just be in my head so I used a pulse ox finger sensor and it is true. Usually my heart rate will be in the 70's and the I bend over...

So I was reading my book and studying for my finals when all of a sudden I felt my heart beating faster. My normal resting heart rate is around 82 but when I took my resting heart ...show more

I know that people experience decrease in heart rate when using opiates, why does my heart rate increase? is this an allergic reaction?

I've been developing fears and worries followed by sudden acceleration of heart beat, especially in the morning and when I stepped out of home. But no sweat or blood rush or trembling. It's just that all of a sudden, I would get uneasy feeling about...

Ok for about a few nights now this has happened. I will be laying in bed, and I suddenly jerk awake and my heart starts pounding really hard and fast. I can literally feel my heart beat in my head and chest. It last for about 20 seconds. Sometimes I...

My pulse is usually around 70-80bpm while sitting. However, upon standing my heart rate increases to around 110-120bpm. (And remains this rate for at least 2 minutes). I usually end ...show more

So, yesterday i was studying for my exams when suddenly i realized that its becoming a little difficult to respire and my heart beat is thumping very high. For about 5 mins i tried to control it by drinking water and roaming, but it had no effect. Finally...