Person-centred care is vital for dementia patients in hospitals to prevent stress-induced behaviors. My team has developed WhatMatters, an app that allows family members to remotely share reassuring videos, familiar photos and music to comfort patients in hospital. This study assesses the effectiveness of the mobile app, WhatMatters, in improving quality of life and reducing behaviors. The results will contribute to improving hospital dementia care by preventing unnecessary, risky, and costly behavioural events, such as antipsychotic medications, falls, and injuries —that can severely affect quality of life.