My mom had one experience of sleep paralysis in her life, she was laying awake in bed, when suddenly fear came over her so strongly that she couldn’t speak and couldn’t move. She thought she saw a dark form at the end of her bed, then closed her eyes because she was scared. She could feel the spiritual presence of evil, and felt as if someone put both hands on her chest and leaned into her. She thought in her mind “Jesus, Jesus,” two or three times thinking his name, because she couldn’t speak it, and the moment she thought his name, the fearful feeling, the demonic presence, and the pressure on her chest, quickly receded and was gone. She was still scared after the demonic presence left, but she could move and speak again, she was not nearly as scared as she was during the sleep paralysis. My mom thinks the experience lasted about twenty seconds, but says it felt like it lasted longer. She was a new Christian at the time, just 18 years old. It has never happened to her since then.
For more information on sleep paralysis, I recommend watching my Christianity vs. The Occult playlist, particularly Sleep Paralysis, Spiritual Warfare and My Story, More on Spiritual Warfare and Recent Attacks, and Sleep Paralysis Revisited.
If you would like to learn more about demons and what they do, these two books will teach you what you want to know: