If a person had sleep apnea could it cause them to have palpitations such as premature atrial contractions during the day? how does sleep apnea cause palpitations, stress on the heart? vagus nerve:nervous system? thanks?

The heart requires a continuous oxygen and glucose supply to function. Sleep apnea, if severe, depletes the blood level of oxygen traveling around the body. As an organ quite sensitive to oxygen deprivation the decline could develop rhythm changes at the time. I don't see it triggering any rhythm changes at other times when O2 level is normal.

Agree with Dr. Ferguson. In addition the person is likely to be obese, have hypertension and may be diabetes and all of these can affect the heart. If the person is obese, losing weight is of paramount importance. Wish you good health!