Gravity is the strongest force in all aspects of life, including your body and it's internal organs - which is why the side of your body you decide to sleep on can affect how your digestive system functions! Basically your left side is the good and healthy side, and your right is the bad and dangerous side!
Your lymphatic system primarily dumps into the left side above your heart, so lying on your left side allows this natural draining to take place in your lymphatic system. Your spleen is one of the major organs of the lymphatic system, and when sleeping on your left, the entire lower extremity of the body drains into the spleen.
How you move waste out of your body determines a large portion of your overall health. Your intestinal tract (small and large) dump food into each other - so lying on your left side helps the large intestine dump into the smaller one effortlessly.
Food works it's way into the descending colon which is on the LEFT side of your body! This supports the dumping of all the waste of your body. When you wake up in the morning, stand up and drink a cup of water, this activates the descending colon for elimination of waste (going #2).
