Piece-rate pay and sleep problems: A study of 942 midnight delivery platform workers in South Korea

Background Midnight delivery platform (MDP) workers engage in the entire delivery process from initial loading to final drop-off overnight, generally between 10 p.m. and 6 a.m. This study investigates the association between pay type and sleep problems among MDP workers in South Korea. Methods We conducted a nationwide survey of 942 Korean MDP workers in 2024. Pay type was categorized into three groups: ‘fixed salary’, ‘piece-rate’, and ‘mixed’. The ‘fixed salary’ workers received a fixed regular income regardless of the number of deliveries they completed, while the ‘piece-rate’ workers earned income entirely based on the number of deliveries they completed. The ‘mixed’ workers received an income combining a fixed salary with additional earnings based on delivery count. Sleep problems over the past month were assessed using three items: ‘non-restorative sleep’, ‘difficulty maintaining sleep’, and ‘difficulty initiating sleep.’ Modified Poisson regression was used to examine the association, adjusting for sex, age, education level, marital status, area, weekly workdays, and monthly individual income. Results The prevalence of non-restorative sleep, difficulty maintaining sleep, and difficulty initiating sleep were 63.6%, 38.6%, and 32.9%, respectively. Compared to ‘fixed salary’ workers, non-restorative sleep was more prevalent among the ‘piece-rate’ and ‘mixed’ workers (piece-rate: PR 1.83, 95% CI 1.28-2.63, mixed: PR 1.93, 95% CI 1.35-2.77). Difficulty maintaining sleep was more prevalent among ‘mixed’ workers compared with ‘fixed salary’ workers (PR 1.62, 95% CI 1.09-2.41). No statistically significant association was found regarding difficulty initiating sleep. Conclusions Pay including a piece-rate component may be associated with a higher prevalence of self-reported sleep-related symptoms among MDP workers.