I found this about which side to lie on when you have GERD.
"Right Side: It’s not Right for Acid Reflux
Position #2 to avoid at night is…sleeping flat on your right side. When lying flat on your right side, your stomach is actually above your oesophagus creating a leaky faucet spouting stomach acid into the delicate lining of your oesophagus. This is especially true when your stomach is full. Interestingly, when lying flat on your right side, your reflux symptoms tend to be more liquid in nature4 leading to regurgitation, coughing, and choking, which can be very scary in the middle of the night. Since gravity is doing nothing for you in this position, the amount of time acid lingers in your oesophagus is much longer so stay off your right side.
So, back sleeping is bad. Right side sleeping is bad. What’s a GERD sufferer to do?
Left Side: Reduces Reflux
Sleep on your left side. Gravity will work in your favour on your left side as your stomach is now positioned below your oesophagus, which makes reflux more difficult. Should stomach acid escape, gravity is able to return it to your stomach quicker than when on your right side or on your back which is why the left is usually the best side to sleep on to avoid acid reflux. Where the right side often produces liquid reflux, when on your left side, reflux symptoms tend to be more gaseous in nature, which may be annoying but much less distressing. Studies show that symptoms are less frequent and less severe when on your left side as compared to on your right side or on your back7 making it the most desirable flat sleep position"
Taz
