Chronotype Prior to Shift Work Influences Outcomes: Resilience as a Mediator of Sleep and Mental Health.

Study Objectives: Despite persistent nursing shortages, newly hired nurses inevitably engage in shift work (SW), which harms their sleep and mental health, accelerating their early-career turnover. This study examined whether pre-SW chronotype is associated with post-SW sleep/mental health outcomes and whether resilience mediates these relationships.

Methods: A prospective cohort of 595 newly hired nurses, of whom 331 were included in the final analysis, was recruited from two national tertiary hospitals. Participants provided baseline and 6-12 months follow-up data after SW exposure. Chronotype, resilience, sleep outcomes (sleep quality and daytime sleepiness) and mental health outcomes (depression, anxiety, and stress scales) were assessed at both baseline and follow-up using validated self-report questionnaires. Structural equation modeling examined direct and indirect pathways linking baseline chronotype to follow-up resilience and sleep/mental health outcomes.

Results: Among 331 nurses (age: 23.4±1.2 years, 293 females, 26 morningness, 186 intermediate, 119 eveningness), the morningness group exhibited the highest resilience at both baseline (p = 0.0206) and follow-up (p = 0.0002). Baseline chronotype was significantly associated with resilience following SW (β = 0.259, p < 0.01). Baseline chronotype further indirectly affected both excessive daytime sleepiness (β = -0.013, 95% CI: [-0.025, -0.001]) and mental health (β = -0.045, 95% CI [-0.066, -0.009]) via resilience.

Conclusion: Pre-SW chronotype significantly influenced post-SW sleep and mental health outcomes, with resilience serving as a key mediator. These findings highlight the potential for targeted interventions-such as resilience training or chronotype-based scheduling-to mitigate early SW-related mental health challenges and reduce nurse turnover.