In fact, it's theorized that much of humanity's belief in such phenomena stems from this one weird brain misfire. That's how realistic these waking dreams can be. They've motivated generations of people to call for exorcisms or just move out of the damned house altogether.
When The Visions Aren't Shadow People, They're Even More Horrifying
Sleep paralysis hallucinations can be visual, like the shadow people, or auditory, which seems to mostly consist of hearing horrific screeching, like someone stepping on a Lego made of nails. Many times, the shadow people just kind of surround your bed. Sometimes they'll move. Sean described an experience wherein he saw a shadow person flailing like a Wacky Inflatable Tube Man. But when he was a child, he had an experience in which he hallucinated seeing his mother.
"I was very young, probably five or six, and I remember my mother coming into my bedroom late one night. I remember not being able to move and thinking that there was definitely something wrong and my mother coming to help. But as she got closer to the bed, I remember her movement looking strange and unnatural. Her face was different somehow, and before I knew it, she was sitting on my bed and staring down at me, smiling. I couldn't react, and soon her face slowly morphed into something demonic-looking, still smiling at me, and I felt a heavy pressure and closed my eyes, unable to cry out."
Years later, as an adult, Sean's wife turned up in another sleep paralysis vision. "I wake up one night to my wife talking to me, but her voice is kind of slurred and distorted. At first I'm confused and trying to figure out what's going on, and it slowly dawns on me that I can't move and am having an episode. Once this realization occurs, her voice goes to normal and she says, 'Oh, by the way, I'm not really Emily,' and then suddenly something grabs my throat and starts choking me."