left hand side is always better.  however you can change positions for a bit when tired from sleeping on your left.  trying using pillows one thin to go under your tummy and one under your knee.  it helped me

left hand side

sleep on your left side , it helps in blood flow dnt sleep on your back.

No renu, avoid sleeping on your back, as your heavy uterus puts pressure on vanacava, the vein which carries blood to heart, I've also heard sleeping on back during pregnancy can cause hemorrhoid

left side but you can change ur side for a while. avoid on your back.