Objectives: Poor and fragmented sleep is a common problem amongst patients hospitalized on medical wards, and is associated with a number of poor outcomes. The present study aimed to objectively measure night-time sleep duration and efficiency in an acute medical ward, and to identify barriers to sleep in this setting. Methods: Fifty-four consecutive patients on an acute medical ward were observed with wearable actigraphy devices for one night, then administered the Richards-Campbell Sleep Questionnaire and a semi-qualitative questionnaire to determine the major barriers to sleep. Results: Patients had a wide variety of reasons for admission. Mean overnight sleep duration was 4.6 hours, with mean sleep efficiency 63%. The Richards-Campbell Sleep Questionnaire mean was 52/100, indicating poor quality sleep. Major barriers to sleep identified were the need to urinate, pain, noise, and light. Conclusions: A mixture of environmental and illness-related factors contribute to poor sleep in the hospital setting. Further research looking at ameliorating these factors may improve sleep and recovery in this population.