Work

Associations between working hours, sleep status, and cumulative fatigue: a cross-sectional study among platform-based parcel delivery couriers in China

Year: 2026

Type: article

Abstract: Platform-based parcel delivery couriers in China often endure prolonged working hours and poor sleep, yet the joint association of these exposures with cumulative fatigue (CF) has not been well characterized. This study aimed to examine the independent and joint associations of working hours and sleep status with CF in this population. This cross-sectional study included 6,619 couriers recruited from seven provinces/municipalities using a mixed sampling design. Working hours were categorized as < 55, 55–<70, 70–<85, and ≥ 85 h/week. Sleep status comprised short sleep duration (< 7 h/night vs. ≥7 h/night) and the presence of insomnia symptoms. CF was assessed with a validated 20-item scale, with CF defined as a score ≥ 2. We used design-adjusted logistic regression, with province as stratum and enterprise as cluster and assuming equal selection probabilities because sampling weights were unavailable, to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs). Restricted cubic splines were used to explore dose–response relationships. Joint associations were examined separately for short sleep and insomnia symptoms. Participants were cross-classified into eight mutually exclusive groups based on the combination of four working-hour categories and each sleep indicator, with the lowest-exposure group as the reference. Multiplicative interaction was tested with product terms, and additive interaction was quantified by the relative excess risk due to interaction (RERI) and the attributable proportion due to interaction (AP). The prevalence of CF was 23.1%. In fully adjusted models, compared with working < 55 h/week, the aORs (95% CIs) for CF were 1.54 (1.25–1.90) for 55–<70 h/week, 2.10 (1.69–2.61) for 70–<85 h/week, and 4.17 (3.17–5.49) for ≥ 85 h/week. Short sleep (aOR = 2.87, 95% CI 2.55–3.23) and insomnia symptoms (aOR = 1.91, 95% CI 1.62–2.25) were independently associated with higher odds of CF. Dose–response analyses showed a non-linear association for working hours and an inverse, predominantly monotonic association for sleep duration, with the steepest increase in CF odds below 7 h/night. In joint analyses, couriers working ≥ 85 h/week with short sleep had the highest odds of CF (aOR = 12.36, 95% CI 9.18–16.64), and those working ≥ 85 h/week with insomnia also had markedly elevated odds (aOR = 9.97, 95% CI 7.02–14.16). On the additive scale, positive additive interactions were observed for both sleep indicators (AP = 0.33 for short sleep; AP = 0.38 for insomnia). Long working hours and poor sleep are independently and jointly associated with substantially higher odds of CF among Chinese delivery couriers. Integrated strategies addressing both work-hour regulation and sleep health promotion may help reduce CF. However, given the cross-sectional design, these findings should be confirmed in longitudinal studies before definitive causal or policy conclusions are drawn.

Source: BMC Public Health

DOI: 10.1186/s12889-026-29788-7

Authors: Jin Wang, Jingjing Du, Xia Wan, Shuang Li, Xin Sun

Institutions: Chinese Center For Disease Control and Prevention, Chinese Academy of Medical Sciences & Peking Union Medical College, National Institute for Occupational Health and Poison Control, Institute of Basic Medical Sciences of the Chinese Academy of Medical Sciences

Language: English

Topic: Sleep and Work-Related Fatigue

Subfield: Experimental and Cognitive Psychology

Field: Psychology

Domain: Social Sciences

SDGs: Good health and well-being, Decent work and economic growth

Open Access status: gold

Estimated APC paid: $3,290