Your body works full time even while you sleep. Try to apply some tricks to help your body during the night, so it can do what is best for you.
Studies have shown that sleeping on the left side is the best. Those who tend to “migrate” the left side of the marital bed look happier than their “right-sided” partners. Posture during sleep is usually a work of comfort and big number of people are turning in their sleep and changing postures.
If you are recommended to sleep on the left side due to medical reasons, it would be good to sleep with a pillow behind your back which will stop turning over the other way during the night.

          1- Improved heart function

Your heart is from the left side of your body, so it makes sense that by sleeping on that side, lymphatic drainage of the heart will be aided by gravity, removing any burden of heart while you sleep.
           2- Better elimination
Sleeping on the left side allows by gravity to push waste from the food to pass into the small bowel.

           3- The spleen is located on the left side

The spleen is part of the lymphatic system that is also located on the left side. The spleen is like a giant lymph node which, besides it’s filtering lymph it also filters the bloods. When you lie on your left side, the gravity is one that helps the drainage system, the same way it helps the heart.
Apart from these, here are the other benefits of sleeping on the left side.
        4- Prevents pressure on the liver
        5- It is good for circulation
        6- Improves blood flow to the fetus, uterus and kidney
        7- Relieve back pain