by gunggang777 » Tue Sep 20, 2011 6:18 am
Sleep paralysis
During REM sleep the body paralyzes itself as a protection mechanism to prevent the movements that occur in the dream from causing the physical body to move. However, this mechanism can be triggered before, during, or after normal sleep while the brain awakens. This can lead to a state where the awakened sleeper feels paralyzed. Hypnagogic hallucination may occur in this state, especially auditory ones. Effects of sleep paralysis include heaviness or inability to move the muscles, rushing or pulsating noises, and brief hypnogogic or hypnopompic imagery. Experiencing sleep paralysis is a necessary part of WILD, in which dreamers essentially detach their "dream" body from the paralyzed one
From wikipedia