The aim of the present study is to implement a novel body-worn sensor, the ZephyrTM BioModule (the registered name for the wearable sensor device used in our study), for assessing physical activity and physiological measures in a clinical setting together with other clinical routine assessments. Our specific aim is to explore whether and how specific physical activity pattern and physiological measures are associated with delirium in hospital inpatient. Our ultimate goal is early detection and intervention of delirium, and better management through monitoring of activity pattern and physiological information. The ZephyrTM a U.S. FDA-approved wireless, ambulatory physiological monitoring device that consists of a data logger and transmitter unit which is attached at the location of the 5th intercostal space using a specifically designed patch (BioPatchTM) and standard ECG electrodes. The ZephyrTM is designed for long-term measurement of a patient's physical activity and physiological measures. By using the physical activity parameters and physiological measures, a specific delirium risk profile will be computed for each patient. Finally, the association of this delirium risk profile with CAM-ICU questionnaire as a gold standard will be assessed.