And there’s this thing called the ileocecal valve. Sleeping on the left is said to help move waste from the small to the large intestine. Gravity does its thing, making for smoother bowel movements.
But remember, left-side sleeping isn’t a must. Different positions have different benefits.
The key is to be comfy all night. If one position bugs you, switch it up. Side sleeping can be tough on your shoulders if you don’t move around, so keep that in mind.