BMJ openSep 8, 2020

Night-shift work, sleep quality, and health-related quality of life in manufacturing workers

Circadian Biology Weekly Brief ↗PubMed ↗DOI ↗OA ↗

Updated Mar 29, 2026

Abstract

Night-shift workers had significantly lower mean scores in all eight domains of (HRQoL) compared to non-night-shift workers (p<0.001).

Night-shift work is associated with poorer sleep quality, including longer sleep latency, shorter sleep duration, sleep disturbances, and daytime dysfunction.
Mediation analyses indicate that overall sleep quality mediates the relationship between night-shift work and HRQoL.
Subjective sleep quality and sleep disturbances specifically mediate the impact of night-shift work on physical well-being.
Sleep latency and daytime dysfunction are identified as mediators affecting the mental well-being of night-shift workers.

Simplified

OBJECTIVES: Night-shift work may adversely affect health. This study aimed to determine the impact of night-shift work on (HRQoL), and to assess whether sleep quality was a mediating factor.

DESIGN: A cross-sectional study.

SETTING: 11 manufacturing factories in Malaysia.

PARTICIPANTS: 177 night-shift workers aged 40-65 years old were compared with 317 non-night-shift workers.

PRIMARY AND SECONDARY OUTCOMES: Participants completed a self-administered questionnaire on socio-demographics and lifestyle factors, 12-item Short Form Health Survey V.2 (SF-12v2) and the (PSQI). The Baron and Kenny's method, Sobel test and multiple mediation model with bootstrapping were applied to determine whether PSQI score or its components mediated the association between night-shift work and HRQoL.

RESULTS: Night-shift work was associated with sleep impairment and HRQoL. Night-shift workers had significantly lower mean scores in all the eight SF-12 domains (p<0.001). Compared with non-night-shift workers, night-shift workers were significantly more likely to report poorer sleep quality, longer sleep latency, shorter sleep duration, sleep disturbances and daytime dysfunction (p<0.001). Mediation analyses showed that PSQI global score mediated the association between night-shift work and HRQoL. 'Subjective sleep quality' (indirect effect=-0.24, SE=0.14 and bias corrected (BC) 95% CI -0.58 to -0.01) and 'sleep disturbances' (indirect effect=-0.79, SE=0.22 and BC 95% CI -1.30 to -0.42) were mediators for the association between night-shift work and physical well-being, whereas 'sleep latency' (indirect effect=-0.51, SE=0.21 and BC 95% CI -1.02 to -0.16) and 'daytime dysfunction' (indirect effect=-1.11, SE=0.32 and BC 95% CI -1.86 to -0.58) were mediators with respect to mental well-being.

CONCLUSION: Sleep quality partially explains the association between night-shift work and poorer HRQoL. Organisations should treat the sleep quality of night-shift workers as a top priority area for action to improve their employees' overall wellbeing.

Key numbers

45.35

Lower SF-12 Score

SF-12 Physical Component Summary score for night-shift workers

6.3

Higher Global Score

global score for night-shift workers

177 of 494

Night-Shift Worker Proportion

Total number of night-shift workers in the study

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Night-shift work, sleep quality, and health-related quality of life in manufacturing workers

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