It's getting kind of heavy-Linking episodes of sickness presence to changes in fatigue over time

Sickness presence-working while being ill-is an episodic goal-directed behavior that depends on health events. Drawing on allostatic load theory, we adopt a temporal perspective to study associations between sickness presence and fatigue both across weeks and within weeks. We theorize that sickness presence episodes are associated with immediate increases in fatigue and that accumulating sickness presence episodes increase within-person fatigue over multiple workweeks. We further examine short-term temporal cycles underlying these long-term trajectories, namely workweek strain and weekend recovery. We expect that the duration of sickness presence episodes is associated with steeper increases in fatigue within person during the workweek and altered patterns of change within person during the weekend. We test our assumptions with a week-level study with 123 employees over 16 consecutive workweeks. Participants reported sickness presence episodes during the week on Fridays and fatigue on Fridays and Mondays. Discontinuous growth models based on 734 weekly self-reports suggest that sickness presence episodes are associated with immediate increases in fatigue and hardly any recovery in the following weeks. Frequent sickness presence episodes contributed to increases in fatigue over time. Longer sickness presence episodes were associated with higher initial levels of fatigue on Mondays and no change in fatigue during the workweek. The duration of sickness presence was unrelated to changes in fatigue during weekends. In summary, our study provides a more precise description of how between-person differences in fatigue, as reported in the literature, may emerge from discrete sickness presence episodes. (PsycInfo Database Record (c) 2025 APA, all rights reserved).