BackgroundDisturbed sleep among people living with dementia in nursing homes is widespread and is associated with diseases and all-cause mortality. This study examined the sleep of people living with dementia from their perspectives in nursing homes and that of the nurses who care for people living with dementia.MethodsA qualitative cross-sectional study was conducted. A total of 15 people living with dementia and 15 nurses in 11 German nursing homes were enrolled in this study. Data was collected between February and August 2021 through semistructured interviews, which were audio recorded and transcribed. Thematic analyses were performed by three independent researchers. Thematic mind maps and controversial findings were discussed with theResearch Working Group of People with Dementiaof the German Alzheimer Association.ResultsThematic analysis identified five overarching themes from the nursing home participants regarding sleep patterns: (1) characteristics of good sleep, (2) characteristics of bad sleep, (3) personal influences of people living with dementia on sleep, (4) environmental factors on sleep, and (5) sleep strategies of people living with dementia. Analysis also identified five overarching themes from the nurses participants: (1) characteristics of good sleep, (2) characteristics of bad sleep, (3) personal influences on sleep, (4) environmental factors on sleep, and (5) interventions for sleep promotion.ConclusionsThe thematic analyses demonstrated that the perspectives of people living with dementia and nurses indicate the need to give more consideration to psychosocial factors and individual aspects of sleep in clinical practice. The results could also be helpful for the development of targeted assessment instruments and complex non-pharmacological interventions to promote sleep.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12877-023-04052-4.