Objectives This study aimed to (i) examine longitudinal changes in psychosocial work factors and mental health during the three years preceding long-term mental health-related sick leave among teachers and (ii) determine whether within-person changes in job demands and resources were associated with psychological distress.

Methods Annual occupational stress surveys conducted from 2010–2023 were linked to administrative sick-leave records for 505 elementary and junior high school teachers who experienced a first mental health-related sick-leave episode lasting ≥180 days. Trajectories from three years before to immediately before leave were estimated using linear mixed-effects models. Within-person associations between psychosocial work factors and psychological distress [measured by the six-item Kessler Psychological Distress Scale (K6)] were examined using person-mean decomposition. The overall teacher population was used as a descriptive standardization reference.

Results Psychological distress and stress responses increased as sick leave approached, whereas quantitative and qualitative job demands remained relatively stable. Job control, coworker support, supervisor support, and work engagement generally became less favorable. Within-person analyses showed that higher-than-usual quantitative and qualitative job demands were associated with higher concurrent K6 scores, whereas higher-than-usual job control, supervisor support, coworker support, and work engagement were associated with lower K6 scores (all P<0.001).

Conclusions The years preceding long-term mental health-related sick leave were characterized by worsening psychological distress and deterioration in perceived job resources rather than a progressive increase in general job demands. Psychosocial work perceptions and distress covaried within individuals, although their temporal and causal direction could not be determined.

Key terms job demand; job resource; longitudinal study; mental health; occupational stress; psychological distress; sick leave; sickness absence; teacher; trajectory; workplace support

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