Objective Drawing on the effort‐recovery model of work stress, this study examined the effects of school teachers’ sleep quality and time spent in various non‐work time activities on work‐related stress and motivational outcomes. We proposed that sleep quality and different types of non‐work time activities would have differential effects on levels of work‐related fatigue and engagement. Method Nine hundred and sixty Australian school teachers (mean age 46 years, 707 females, 237 males) completed a cross‐sectional online survey measuring sleep quality, time spent in non‐work time activities, and work‐related fatigue and engagement. Results Teachers spent relatively higher amounts of time on work‐related activities outside of formal work hours, and lower amounts of time on health‐promoting activities such as exercise. Multiple regression analyses indicated that sleep quality was related to reduced fatigue and increased engagement, while time spent socialising outside of work was related to reduced fatigue. Time spent on work‐related tasks outside of working hours was related to both increased fatigue and engagement. Other activities, including passive activity, exercise, and hobbies, were not significantly related to either outcome. Conclusions We discuss the implications of our findings in relation to theories and research in work stress, particularly in the context of where priorities should be placed for self‐care interventions to facilitate teachers’ day‐to‐day recovery from work demands.