Sundowning, a change in the behaviour of a person with dementia that appears in the evening or during the night, is a well-recognised occurrence in dementia care. The behaviours observed can be agitation, aggression, anxiety or those associated with delirium. This article uses case studies to illustrate the ways in which sundowning may present, and explores possible rationales, approaches and interventions that might be useful in supporting the person, family carers and caregivers.