My understanding is, your stomach is slightly to one side (a bit like your heart is; you’re only symmetrical on the outside) and so laying on one side, your stomach is above your centerline, if you lay on the other your stomach is below your centerline. Sleeping with your stomach on the “high side” means its easier for stomach acid to leak up into your esophagus, which burns!
My understanding is, your stomach is slightly to one side (a bit like your heart is; you’re only symmetrical on the outside) and so laying on one side, your stomach is above your centerline, if you lay on the other your stomach is below your centerline. Sleeping with your stomach on the “high side” means its easier for stomach acid to leak up into your esophagus, which burns!