Sleep paralysis is a condition that can occur when you’re transitioning into or out of rapid eye movement (REM), a phase of sleep in which you may experience dreams and muscle paralysis. During a sleep paralysis episode, you have some awareness of your surroundings but are temporarily unable to move or talk. Some people also experience hallucinations, where they hear imaginary voices, see dark figures in the room, or feel an ominous presence. The experience can be distressing, but aside from the discomfort it brings, sleep paralysis is typically harmless. It sometimes occurs alongside sleep disorders such as narcolepsy.