my heart races when I wake up in the morning, I tend to feel nervous when I wake up and realize my heart is racing, I have had a 24 hr heart monitor, and blood work everything came back normal, the symptoms started to go away and for months I didn't have the issue anylonger, until just the past month it has started again, im afrain I will have a stroke, im 47 I don't drink or smoke, or use drugs, I excersize, and eat somewhat healthy, I have cut sugar out of my diet a few weeks ago ,I don't drink coffee, ? what could be wrong with me