Why when Im laying in bed getting ready to go to sleep, usually laying on my right side, all of a sudden, no pain, just I feel my left chest area quivering and it becomes more pronounced enough that I almost feel as if my whole chest / rib area is quivering or like a shiver for what feels like a minute but is probably only 5 - 10 seconds give or take.  It doesnt happen every night and I only seem to notice it when Im getting ready to go to sleep.  Again no pain or anything to cause me to be scared just a strange strong quiver or shiver feeling.
Thanks for your question on Chat Doctor. I can understand your concern. Possibility of stress and anxiety related symptoms is more. But better to first rule out heart diseases like arrhythmia. Arrhythmia is rhythm disturbance in heart and this can cause shivering, fluttering, quivering feeling in left sided chest. So better to get done ECG, 2d echo and Holder monitoring (24 hour continuous monitoring of ECG). If all these are normal then no need to worry about arrhythmia or other heart diseases. Stress and anxiety appear more likely cause. So avoid stress and tension, be relaxed and calm. Consult psychiatrist and get done counseling sessions. Try to identify stressor in your life and start working on its solution. You may need anxiolytic Chat Doctor.  Don't worry, you will be alright. But first rule out heart diseases like arrhythmia. Hope I have solved your query. Wish you good health. Thanks.