Journal of nursing managementApr 24, 2026

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

Circadian Biology Weekly Brief ↗PubMed ↗DOI ↗OA ↗

Updated Jun 28, 2026

Abstract

Essence

Among shift-working nurses, circadian rhythm traits were more strongly linked to sleep, depression, and safety behavior than measured shift work demands.

Evidence

This cross-sectional study of shift-working nurses at one tertiary hospital used questionnaires plus objective scheduling records and SEM/GAM analyses, finding languidity tied to worse sleep and depression and flexibility tied to better safety behavior.

Caveat

Because this was a single-hospital cross-sectional analysis explaining only part of the variance, the results show associations rather than proving that changing schedules by circadian traits improves safety.

Simplified

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.