Sundown syndrome in institutionalized elderly.

To describe sundown syndrome and determine factors related to its occurrence, 59 demented and 30 nondemented nursing home residents aged 60 years and above were observed in the morning and the evening over two consecutive days using a Confusion Inventory. Physiologic, psychosocial, and environmental data were also recorded. In addition, Pfeiffer's Short Portable Mental Status Questionnaire, the Philadelphia Geriatric Center Morale Scale, Face-Hand Test, and sensory screening were completed. Among the 89 subjects, 11 were found to be sundowners, a prevalence rate of one in eight in the facility. No clear pattern of behaviors evolved but sundowners were found to increase restless and verbal behavior as evening approached. Sundowners were more likely to be demented, with greater mental impairment and organic involvement than nonsundowners. Among physiologic factors, odor of urine, being awakened frequently on the evening shift, and fewer medical diagnoses were significantly associated with sundowning. Significant psychosocial factors were current room residence of less than one month, more recent admission to the facility, and higher evening levels of confusion. No environmental factors were related.