[sparklite2]

 To help control this unpleasant condition [acid reflux], put your arms in front of you and lie on your right side, says this doctor from Russia.

What horrible advice.  He must be plumbed the opposite from me.

But in a 2011 story, EverydayHealth says "don't sleep on your right side."

 That's more like it.  From what I can visualize, you esophagus plugs into you stomach on the right side.  Lying on your right side makes the sphincter work against gravity, and allows acid to leak down into the esophagus. Lying on the left side, the acid has to flow upwards to get to the esophagus, against gravity.

I took Prilosec for years fighting acid reflux, taking two a day for the last year or two.  Simply sleeping on the correct side and moving off the incorrect side when I could feel acid burn starting, has allowed to me stop taking Prilosec totally for the last year.  Any acid discomfort I have now, which is very rate, two tablets of Alka-Seltzer fixes immediately.  Or a couple of Tums.  Nothing else, and certainly not Pepto-Bismol, which disrupts my intestinal tract for days.

[JPJones]

Best thing for acid-reflux is a cup of water with teaspoon of apple cider vinegar.

Totally works.

[Pete from Shawnee Mission]

Here are some pictures.

https://www.bing.com/images/search?q=stomach+diagram+anatomy&qpvt=stomach+diagram+anatomy&FORM=IGRE

I think its an issue of where the body of the stomach sits when you lie down. If on your right side, gravity drains it into your intestine. If on your left, your stomach has to push stuff uphill into the small intestine and its more likely to backup into the esophagus which is on the downhill side.