Does abnormal breathing trigger an elevated heart rate? Or vice versa.

[G. Szabo]

I discussed these results with a cardiologist and he said that sleeping on the left side can put extra stress on the heart and often causes it to compress a bit against the wall of your chest.  When I sleep on my right side, this problem is nonexistent. 

Just my anecdotal experience.

I have tried to do a systematic search on this subject. Oh boy, what a mess I found. First, you must ignore the TikTok and YouTube academies; second, omit the spiritual advice. Then, you will be left with very few scientific studies.

My summaries of the filtered findings: 
1) You should sleep on your left side if you have no heart condition for several medical reasons.   
2) You should sleep on your right side if you have some heart condition. For example, you will reduce the myocardial infarction rate in this position. What is more, "The rate of nightmare sufferers was significantly higher in left-side sleepers (40.9%) than in right-side sleepers (14.6%). Relief-safety was more common among right-side sleepers than the others."
3) If you are elderly, you tend to sleep on your right, probably because the elderly population is more prone to heart issues.

[icipher]

I have tried to do a systematic search on this subject. Oh boy, what a mess I found. First, you must ignore the TikTok and YouTube academies; second, omit the spiritual advice. Then, you will be left with very few scientific studies.

My summaries of the filtered findings: 
1) You should sleep on your left side if you have no heart condition for several medical reasons.   
2) You should sleep on your right side if you have some heart condition. For example, you will reduce the myocardial infarction rate in this position. What is more, "The rate of nightmare sufferers was significantly higher in left-side sleepers (40.9%) than in right-side sleepers (14.6%). Relief-safety was more common among right-side sleepers than the others."
3) If you are elderly, you tend to sleep on your right, probably because the elderly population is more prone to heart issues.

Interesting. I've had several cardiac workups and everything points to my heart being very healthy. I went into mychart to look at the last message my cardiologist sent me after I complained of irregular heartbeat and sent him the ECG graphs when sleeping on my left side, below is his exact response:

"Rhythm strips show sinus rhythm with occasional PAC's. Is it common for palpitations to be more symptomatic when laying on your left side - the heart is pushed up against the diaphragm and irregularity can be more symptomatic - not a concerning finding."

[G. Szabo]

[quote pid='510704' dateline='1713205514']
"Rhythm strips show sinus rhythm with occasional PAC's. Is it common for palpitations to be more symptomatic when laying on your left side - the heart is pushed up against the diaphragm and irregularity can be more symptomatic - not a concerning finding."
[/quote]

Indeed. A detailed medical report exists on the correlation between ECG characteristics and left-side sleep. The study observed the heart position and shape by MRI when the patient was on the left, right, and back. It found that only the left side position significantly affected the heart position and shape, and the ECG changed accordingly. The study did not claim that it could be a health risk for healthy patients;  it only argued that ECG can be used to identify sleeping positions.

[UnicornRider]

This is interesting. Due to my chemo and radiation therapy, I have to go through an annual assessment of my heart function, they among other things, take sonograms of my heart while flat on my back, then while lying on my left side. I will have to inquire about that. They have never had a right side scan, it may be related to the above listed reasons.

[G. Szabo]

 They have never had a right side scan, it may be related to the above listed reasons.

Correct, there is no ECG difference between the back-side and right-side positions.