Comment by throwaway920102 4 days ago
for people with acid reflux / GERD / heartburn at least, the "sleep on your left side" thing has to do with the layout of the esophagus. For whatever reason, sleeping on your left means that gravity helps work to prevent acid reflux, whereas the opposite is true for the right side. Not sure if there's any benefit other than that
Radiologist here. We actually put patients in LPO (left side down oblique on your back ) followed by RPO to elicit reflux to catch it on the xray camera.
The opposite is RAO (right side down on belly oblique), when we want to show the opposite esophageal emptying into the stomach.
But any one position is probably not good to maintain for a long time. That’s why patients on respirators get turned so they don’t develop pressure ulcers.
Personally I have found 15-20 minutes prone (on my belly) is helpful reducing fatigue after intense exercise.
> For whatever reason
The short answer is that your organs are mostly asymmetric and the esophagus connects to the stomach on the right so by laying on your right your stomach acid flows to the sphincter connecting your stomach and esophagus, making it easier to leak into the esophagus. This is especially a problem with GERD because you don't have pain receptors on that end of your esophagus but the stomach acid can still damage its tissue, which can lead to further complications including cancer.
A common cause of acid reflux is a herniated diaphragm (hiatal hernia) in which part of the stomach slips through the diaphragm into the upper chest. In this the esophageal sphincter will not be the highest point of your stomach, further adding to the problem when sleeping on your right side. Imagine a plastic water bottle deformed in such a way it stands slanted with the opening to the right, now imagine laying it on that side or the other. Laying it on the side with the opening makes it more likely to spill if the lid isn't forming a perfect seal.