Hi, I am a 28year old phd student. 7-8months before I had some breathing prob,dizziness, lightheadedess, palpitations. I went to a cardiologist he said to me to bring a ecg report and my report was normal. After that he suggested me to quit cigarette. It was tough but finally I did it, i don t take any cigarette for 5months. But those problems which i listed above don t leave me. I went to the doc. again. Now, he said to me to have a holter test and tmt test. In my holter test the lowest heart rate is 36/min and max pause 2.4sec, and my tmt report is normal, no Arrhythmia is found, i have completed 4th stage of tmt with ease. I can t say i am like a athlete but I used to exercise regularly. If I have a bradycardia(as doc. said) then why is my tmt is normal, when i have heart rate 60/min then also why i experience lightheadedness, dizziness and another thing in my holter report 36/min was reported when i was sleeping, when I awake my heart rate always in between 50-65/min. Also, I feel better when I exercise, I can run 20min nonstop . Please, tell me how serious my condition is.