Sleep paralysis is paralysis associated with sleep that may occur in normal subjects or be associated with narcolepsy, cataplexy, and hypnagogic hallucinations. The pathophysiology of this condition is closely related to the normal hypotonia that occur during REM sleep. When considered to be a disease, isolated sleep paralysis is classified as MeSH D020188. Some evidence suggests that it can also, in some cases, be a symptom of migraine. Read about it more: http://en.wikipedia.org/wiki/Sleep_paralysis Source: Wikipedia In other words, you wake up but notice that you can move only your eyes (and maybe tongue). In most of cases, you see creepy hallucinations. It's like a nightmare but you're awake. I've been interested about this for quite long time now. Have you experienced sleep paralysis? Tell us about it. Discuss.