Sundown syndrome: etiology and management.

1. Although no clear definition of "sundowning" or "sundown syndrome" exists in the literature, most health care professionals affix either of these terms to the behavior observed in patients with dementia associated with increased agitation and confusion that occurs in the late afternoon. 2. Specific etiologic hypotheses that relate to sundowning behavior include disturbance in Rapid Eye Movement (REM) sleep, episodes of sleep apnea, and a deterioration of the suprachiasmatic nucleus of the hypothalamus. 3. Management of sundowning behavior includes the identification and treatment of any physiologic factors, low doses of specific neuroleptics, and nonpharmacological interventions such as restriction of daytime sleep, exposure to bright lights during the day, and mild activity schedules.