Behavioral changes in the late afternoon and evening—commonly called sundowning or sundowning syndrome—can be one of the most distressing aspects of caring for someone with dementia. Yet, despite how frequently the term is used, there are persistent misconceptions about what it is, why it happens, and how best to respond. Better understanding can make a meaningful difference for both patients and caregivers, says Matthew Mulroy, MD, a UCLA Health internist who specializes in geriatric medicine.