Children who experience nightmares need support and comfort. Environmental factors such as horror films may be important triggers. These situations can lead to a rebound in REM sleep, which promotes nightmares. Sleep paralysis Sleep paralysis is generally associated with sleep-wake transitions but also occurs from REM sleep. This is a brief period of awakening from sleep being unable to move or speak and may be accompanied by auditory or visual hallucinations.
Nocturnal erections are a normal component of REM sleep.
Their occurrence can be used to distinguish organic impotence from impotence of a psychological origin. In rare cases, erections become painful and arouse the sleeper. This syndrome, of apparent attempts to enact dreams, is characterized by complex and vigorous motor behaviours during REM sleep usually with dream imagery. REM sleep behaviour disorder may be associated with neurological conditions such as stroke, dementia, multiple sclerosis and severely stressful events. These headaches that often have their onset during sleep are categorized as sleep disorders associated with neurologic disorders.