This article presents the key findings from an extensive research project aiming to identify the determinants of poor sleep in care homes. A mixed methods study was conducted in 10 care homes in South East England. This included 2-week daily diaries completed by 145 older residents and interviews with 50 care-home staff. This research demonstrated that the regular surveillance by qualified nurses and care assistants at night seriously impedes the quality of sleep experienced by older people living in care homes. However, nurses and social care workers have a duty of care, which would not be fulfilled if regular checks were not undertaken at night. There is a need for care-home staff to strike a balance between enabling older people living in care homes to have a good night's sleep and adhering to their own professional duty of care.