This is a prospective before-after, two-centre study using a mixed-methods design. We will apply 3 work schedules, each for a period of 2 months over a 6 month period in the adult medical-surgical ICUs at two university affiliated hospitals in Toronto. In this mixed methods approach, quantitative and qualitative data will be collected concurrently, analysed separately, and their results compared, to produce an integrated interpretation of the impact of work schedule on the relationship between continuity and fatigue.