The relationship between shift work, sleep, and work hours on wellbeing.

We investigated the role of sleep and work hours on wellbeing among day- and shift workers. We tested a mediation-moderation hypothesis proposing that; 1) sleep would mediate the association between the work schedule and the impact of sleep/sleepiness on wellbeing; 2) work hours would moderate the link between work schedule and sleep. We made random phone calls to 1,162 participants and identified 172-d and 130 shift workers that worked ≥35 h/week. The work schedule had a positive indirect effect on the impact of sleep/sleepiness via sleep duration (β=0.0511, SE=0.0309, [0.0008, 0.3219]. The relationship between shift work and sleep duration was negative (β=-0.35, SE=0.14, p<0.01), and sleep duration was negatively associated with a greater impact of sleep/sleepiness on wellbeing (β=-0.15, SE=0.06, p<0.02). The path between the work schedule and sleep duration was moderated by work hours; fewer work hours resulted in shift workers reporting a greater impact of sleep/sleepiness on wellbeing. The results support the mediation-moderation hypothesis. Work hours and sleep duration are key characteristics in work schedule design.