It promotes the proper elimination of waste products
The junction between the small intestine and the large intestine is situated in the left side of your body, in the area called the ileocecal valve. When you sleep on your left side, the gravitational forces make it easier for the waste products to move from the small intestine to the large intestine. This allows the colon to eliminate waste from your body more quickly.
It may reduce nighttime heartburn
If you suffer frequent heartburn, then it’s a good idea to lie on your left side while catching some z’s. In this position, your stomach will be situated below the cardiac sphincter that connects your esophagus to your stomach. The left-side sleeping position prevents stomach contents from coming back up into the esophagus.