An unusual case of sundown syndrome subsequent to a traumatic head injury. 
An unusual case of sundown syndrome is here reported, in which a bilingual patient would involuntarily change languages at sunset.  Numerous theories have been advanced in attempting to account for sundowning.  Cameron has suggested that nocturnal delirium was based on an inability to maintain a spatial image without the assistance of repeated visualization.  Kral and Wolanin and Phillips have argued for a more psychogenic account, by stating that psychosocial stressors may, in concert with impaired cognitive functioning, account for sundowning.  The present case concerns a 42-year-old white male who in January 1989 suffered a closed head injury.  A thorough personal history as well as a detailed examination of the patient's daily activities allowed us to account for the unusual manner in which the sundowning manifested itself.  The uniqueness of this case allows us to underscore both the psychological as well as environmental and neurological factors involved in sundowning.  Thus, we have as a consequence been able to synthesize the seemingly disparate accounts of both Cameron and more recent published literature.