Exploring how physical activity influences life satisfaction in dual-shift workers, with a focus on the roles of sleep quality, subjective well-being, and the sleep environment

Shift workers face elevated risk of sleep disruption and reduced well-being, yet the pathways linking physical activity to life satisfaction under rotating shift systems remain underexplored. This study examined how physical activity (PA) relates to life satisfaction (LS) among 1,465 migrant manufacturing workers in Dongguan on monthly rotating dual-shift schedules, testing sequential mediation by sleep quality (SQ) and subjective well-being (SWB) and moderation by the sleep environment (SE). We used cross-sectional survey data and estimated mediation and moderated-mediation models with PLS-SEM. Analyses reported path coefficients, explained variance (R²), interaction effects, and 95% confidence intervals to quantify direct and indirect associations between PA and LS. Higher PA was associated with greater LS both directly (β = 0.530, p < 0.001) and indirectly through SE (PA → SE → LS, β = 0.187, p < 0.001), SQ (PA → SQ → LS, β = 0.161, p < 0.001), SWB (PA → SWB → LS, β = 0.044, p < 0.001), and a sequential chain (PA → SQ → SWB → LS, β = 0.032, p < 0.001). Notably, SE significantly moderated the sequential mediation (interaction β = 0.180, p < 0.001), such that more favorable sleep environments amplified PA’s indirect effects via sleep and well-being. The full model explained 41% of variance in LS (R² = 0.409), with the moderator contributing a significant additional increment (ΔR² = 0.028, p < 0.001). At the population level, sleep quality emerges as a central conduit linking physical activity to life satisfaction, while the sleep environment conditions the extent to which behavioral gains translate into improved well-being. For shift-working populations, interventions that combine promotion of physical activity with practical improvements to sleep conditions (for example, dormitory upgrades, sleep hygiene programs, or timing-based activity guidance) are likely to produce more durable benefits than single-domain approaches. Because the study is cross-sectional, longitudinal or experimental research is needed to confirm causal directions and to test phased or timing-sensitive interventions.