Sleep paralysis is phenomenon in which a person temporarily experiences an inability to move, speak, or react. You are stuck in the transitional state between wakefulness and sleep often accompanied by hallucinations. Some people say the experience feels like there’s a super natural being present at the time. It may feel as if they are sitting on your chest or physically restraining your arms, legs, torso, or all of these body parts simultaneously.
Accounts of sleep paralysis can be found in Persian medical texts dating all the way back to the 10th century. People have associated the experience with everything from witches, aliens, creatures such as gargoyles, and ghosts.