Background: Difficulty sleeping is a common symptom for patients living with cancer that significantly affects their lives. However, although sleep disorders are common, it is an overlooked problem in cancer care. Purpose: This study assessed the prevalence of sleep disturbances among patients living with cancer, and assessed the adequacy of sleep assessment and intervention for patients from both nurses' and patients' perspectives. Method: Descriptive, cross-sectional and correlational design was used in this study. A convenience sample of 129 patients with cancer and 113 registered nurses working with cancer patients was recruited. A structured face-to-face interview was used to complete the patients' questionnaires and a self-administered questionnaire was given to nurses. Findings: The majority of patients with cancer reported having poor sleep quality (69.8%). About 86.7% (n=98) of nurses reported that they have never screened patients with cancer for any sleep problems, and 76.7% (n=99) of the patients reported that they have never been assessed for sleep problems by the nursing staff during hospitalisation. Only 8% of patients with cancer who reported having problems sleeping to a nurse received interventions to promote better sleep. Conclusion: Assessment of sleep disturbances in patients with cancer should be unified using a comprehensive reliable valid instrument, as well as providing evidence-based interventions according to patient's need. A written policy should be introduced to encourage sleep documentation and to make sleep care for patients part of routine nursing care.