Other health-related sources have different opinions and it seems that the truth lies somewhere in between good and bad. There is some compelling evidence, which suggests that sleeping on your left side may relieve heartburn and acid reflux symptoms. So, it's great if you tend to suffer from those kinds of ailments on a regular basis.
The reason it relieves heartburn is because sleeping on the right side relaxes the esophageal sphincter to the point of it leaking stomach acid. Sleeping on the left doesn't result in any leakage. Sleeping on your left side while pregnant will also improve your baby's health. When you sleep on your left an increased amount of nutrients makes its way to the placenta. So, it's a yes to left side sleeping if you experience heartburn or if you're pregnant.