Doctors define Sleep paralysis in which there is a temporary paralysis of the body shortly after waking up is experienced and sometimes but not so often shortly before falling asleep.
Patients also complain about hallucinations and paralysis. Like with all forms of sleep disorders it is first important to know the disease so that patients can easily cope with it. Physiologically, it is more like paralysis that occurs as a natural part of REM (rapid eye movement) sleep, also known in medical world as REM atonia.
Quite often, sleep paralysis is imagined by the patient affected by it to be no more than a dream. This explains many dream recountings which describe the person lying frozen and unable to move. The hallucinatory element to sleep paralysis makes it even more likely that someone will interpret the experience as a dream, since completely fanciful objects may appear in the room alongside one's normal vision
Enough researches show that attacks are common when one lying on their back, if that is so then it is obvious to try to find another comfortable sleep position that doesn't trigger this problem.
Main symptom of sleep paralysis is partial and sometimes full skeletal muscle paralysis during the hypnopompic or hypnagogic states. So it is the sense of being aware that one is unable to move or speak while falling asleep or waking up. Sleep paralysis may also be accompanied by hypnagogic hallucinations.