You only go into REM sleep if you are dreaming or something.
That really scares me going into REM sleep when I am dreaming because then I try to wake myself up by screaming! I swear to god that I heard myself screaming. It wasn't a dream that I screamed in my dream! I really tried to wake myself up by screaming! Even Jason heard me one night waking myself up screaming. I swear to god that I literally try to wake myself up screaming. Well since I can't move when I am dreaming or asleep. It's the only thing I can do. Sometimes I can't even scream when I am asleep or dreaming.