5. Less Heartburn
The stomach’s position on the left side of the body may also be the reason that left-sided sleeping can minimize heartburn, while right-sided sleeping can exacerbate it. Scientists don’t understand the exact mechanism, but one idea is that right-side sleeping lets acid into the esophagus by relaxing the lower esophageal sphincter, which lies between the stomach and the esophagus.
Another thought is that a left-side position keeps the junction between your stomach and esophagus above the level of gastric acid. Multiple studies in the The American Journal of Gastroenterology have shown greater heartburn in people who sleep on their right sides after a meal, as well as a longer time taken for the acid to clear.