Circadian Rhythm Traits Matter More Than Shift Work Demands in the Sleep–Depression–Safety Behavior Pathway Among Shift‐Working Nurses

Apr 24, 2026Journal of nursing management

Body Clock Patterns Affect Sleep, Depression, and Safety Behaviors More Than Work Schedule Demands in Nurses Working Shifts

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Abstract

The optimal model explained 44% of the variance in depressive symptoms among shift-working nurses.

Languidity, indicated by a higher score on the vigorous-languid scale, is strongly linked to poor sleep quality and increased depressive symptoms.
Flexibility, measured by the flexible-rigid scale, is positively associated with safety behavior, impacting it both directly and indirectly.
Depressive symptoms are strongly negatively associated with safety behavior, indicating that higher levels of depression may lead to reduced safety practices.
Circadian rhythm traits are more closely related to the sleep-depression-safety behavior chain than shift work demands, which mainly influence safety behavior.
Key predictors of safety behavior include shift schedule entropy, flexibility, chronotype, sleep quality, and depressive symptoms, with predominantly linear effects observed.

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OBJECTIVES: The study examined how shift work demands and circadian rhythm traits influence the sleep-depression-safety behavior chain in shift-working nurses.

METHODS: A cross-sectional study was conducted from May 1, 2024, to May 31, 2025, recruiting shift-working nurses from a tertiary hospital. Their circadian traits, sleep quality, depressive symptoms, and safety behavior were assessed using the Circadian Type Inventory (CTI, measuring flexible-rigid [FR] and languid-vigorous [LV]), the Morningness-Eveningness Questionnaire-5 (MEQ-5), the Pittsburgh Sleep Quality Index (PSQI), the Patient Health Questionnaire-9 (PHQ-9), and the Safety Behavior Questionnaire (SBQ). Objective shift work demands (total night shift count, shift work hours, shift workload exposure, and shift schedule entropy) were calculated based on data from the nursing management system. Piecewise structural equation modeling (SEM) and generalized additive models (GAMs) were used for data analysis.

RESULTS: The optimal SEM explained 22% of the variance in sleep quality, 44% in depressive symptoms, and 22% in safety behavior level. Languidity (higher LV score) was strongly associated with both poor sleep quality (β = 0.29) and depressive symptoms (β = 0.28), whereas flexibility (higher FR score) was positively associated with safety behavior, exerting both direct (β = 0.21) and indirect (β = 0.04) effects. Depressive symptoms showed the strongest negative association with safety behavior (β = -0.27). Circadian rhythm traits showed stronger associations with the sleep-psychological-safety behavior chain than shift work demands, which were mainly associated with safety behavior and only weakly with sleep quality and depressive symptoms. GAMs revealed that five key predictors (shift schedule entropy, FR, chronotype, sleep quality, and depressive symptoms) had predominantly linear effects on safety behavior.

CONCLUSION: Circadian rhythm traits should be prioritized in shift scheduling to optimize the sleep-psychological-behavioral pathway, while balancing shift work demands may help improve their safety behavior among shift-working nurses.