I can definitely attest to the fact that sleeping with someone who snores affects the non-snorer! My husband has sleep apnea and snores horrifically. It keeps me awake if I don’t fall asleep before him, and wakes me up multiple times throughout the night. Elbowing him, trying to get him to roll over, etc. is an effort in futility. He snores regardless of his position.
I suffer from insomnia, since childhood. I am also a stomach sleeper, well, more a hybrid side/stomach sleeper. Generally on the left side due to GERD. It feels better to sleep on my back, due to back pain, but if GERD is acting up, it isn’t happening. Sleep hygiene is important for sure!