Sundowning Syndrome in Dementia: Mechanisms, Diagnosis, and Treatment.

"Sundowning syndrome" refers to the evening decline in mental state among cognitively impaired patients. This phenomenon is well known, but it is not entirely understood. Its prevalence ranges from 1.6% to 66% of patients with dementia. Development of SS relies on neurodegeneration, the presence of sleep disorders, circadian rhythm of patients' activities, and mood disorders. Therefore, patients with SS need very precise diagnostic workup aiming at defining the exact cause of the syndrome. Potential therapeutic modalities include behavioral and environmental interventions and pharmacological approaches. Pharmacotherapy with sedatives can by effective but is related to severe side effects. Behavioral interventions are more efficacious but require intense involvement of caregivers. This article discusses the biological processes that may underlie SS and proposes potential diagnostic procedures and therapeutic interventions.