Studies show that sleeping on your left side is best. Those who have a tendency to migrate to the left of a double bed are apparently happier than their ‘right’ counterparts.
Sleep position is often a matter of comfort, and most people change positions while sleeping and find themselves waking in a different position than the one in which they fell asleep. If it is recommended that you sleep on your left side for medical reasons, you can try sleeping with a pillow or a tennis ball behind your back to prevent you from rolling over.
The reason is not entirely clear. One hypothesis holds that right-side sleeping relaxes the lower esophageal sphincter, between the stomach and the esophagus. Another holds that left-side sleeping keeps the junction between stomach and esophagus above the level of gastric acid.
7 Reasons to sleep More On left side
Better Heart Function
One of the biggest players on the left side is the heart. It makes sense that if you sleep on your left side, the lymph drainage toward the heart will again be helped by gravity, taking some of the workload off the heart as you sleep.
The small intestine dumps waste through the ileocecal valve (ICV) on the right side of the body into the beginning of the large intestine. The large intestine travels up the right side of your belly the across the tummy, where it dumps waste into the descending colon on the left side.
Sleeping on the left side allows gravity to encourage the food waste to move more easily from the small intestine into the large intestine through the ICV.
Spleen Is On the Left
The spleen, which is part of the lymphatic system, is also on the left. The spleen is much like a gigantic lymph node, except that in addition to filtering lymph it also filters blood. When you lay on the left side, drainage back to the spleen is once again helped and made easier by gravity.
-Prevents the uterus from applying pressure to the liver (which is on the right side of the body).
-Is beneficial to circulation.
-Improves blood flow to the fetus, the uterus, and the kidneys.
-Takes pressure off the back, which may alleviate typical pregnancy-related back pain.
If you have chronic heart failure or have had a heart attack, sleeping on your right side (instead of the left) may be recommended by your physician. Sleeping on your right side may lower your heart rate and your blood pressure. Sleeping on your left side may have a negative effect on sympathetic nervous activity (which includes heart rate and blood pressure).