Sleep paralysis among medical students.

Sleep paralysis is a sensation of an inability to speak or move other muscles when falling asleep or awakening. Sleep paralysis by itself has been reported as occurring infrequently and many clinicians are uncertain of its significance. In contrast, sleep paralysis in conjunction with sleep attacks has been reported as a concomitant of narcolepsy. To further examine the incidence of sleep paralysis, the responses of 80 first-year medical students, 16.25% had experienced predormital, postdormital, or both types of sleep paralysis. These episodes occurred infrequently--only once or twice for most of these students. Reports of sleep paralysis were not associated with sleep attacks or cataplexy. These results support two previous studies which found that sleep paralysis alone occurs frequently among normals.