You wake up to sneeze
While REM sleep turns off some neuro-sensors which make sneezing almost impossible, REM isn’t ALL of your sleep and normal symptons can creep in while not in REM sleep and wake you up and cause a sneezing attack. If you’ve ever had allergies or are allergic to the poisons typically sprayed on GMO crops, you’ll know that sneezing attacks in bed are quite common. But do you honestly think you could sleep thru a sneeze which produces “winds” > 200mph? No. You will wake up, then sneeze, then probably need many tissues to clear your sinuses in order to get your head back to a state you can sleep again.
So the simple answer is, you always wake up to sneeze, they don’t just go away. Some of the worst sneezing attacks, in fact, come right after waking up in the middle of the night or early morning as your REM sleep gets lighter or takes a break.