i have the same thing
I'm a male, 60+, fairly fit... I have these. If I drink more than a few glasses of wine: they usually start at about 3am. Deep, heavy thuds, at around 80 bpm. I have found that regular deep breathing (count 4 in, stay for 4 with breath retained, count 4 out, stay for 4 with breath exhaled...) for about 2 mins - actually helps! I reckon it's stress at a deep, almost unconscious level. Try to figure out what's REALLY eating you. Once I figure it out for myself, I'll tell you all!
Reading your posts helps a lot I also have this kind of problem.im only 26 yrs old and i have a series of palpitations since i was in college. Perhaps its because of stress. But last yr was really scary cause i have a heart rate of 140bpm, that i need to rushed myself to the hospital.I've done series of exams which includes 2D echo,ECG and more. the only diagnosis sinus tachycardia. I hope we all get better soon. God bless!