<Tr> <Th> Frequency </Th> <Td> 8--50% </Td> </Tr> <Tr> <Td_colspan="2"> (edit on Wikidata) </Td> </Tr> <P> Sleep paralysis is when, during awakening or falling asleep, one is aware but unable to move . During an episode, one may hear, feel, or see things that are not there . It often results in fear . Episodes generally last less than a couple of minutes . It may occur as a single episode or be recurrent . </P> <P> The condition may occur in those who are otherwise healthy, those with narcolepsy, or may run in families as a result of specific genetic changes . The condition can be triggered by sleep deprivation, psychological stress, or abnormal sleep cycles . The underlying mechanism is believed to involve a dysfunction in REM sleep . Diagnosis is based on a person's description . Other conditions that can present similarly include narcolepsy, atonic seizure, and hypokalemic periodic paralysis . </P>

What is it called when you are sleep and can't move