Background: Shift-workers may experience sleep disturbances more frequently than day-workers. Interactions between obstructive sleep apnea (OSA), shift-work and other factors promoting sleepiness have never been studied. The present study was designed to assess the prevalence of excessive daytime sleepiness (EDS), high risk for OSA (HR) and insomnia in shift-workers and day-workers and to evaluate their mutual effects on the risk of home-to-work commuting car accidents or episodes of falling asleep during work.
Methods: Workers (153 shift-workers, 85 day-workers) were evaluated for the presence of sleep disorders including HR and EDS. The relationships between sleepiness-related events, shift-work and sleep disorders were investigated by path analysis.
Results: Forty-nine subjects had HR. EDS was more frequent in shift-workers than in day-workers (16.3% vs. 5.9%, P = 0.01) and in workers with HR (28.6% vs. 8.4%, P < 0.001) or insomnia (35.7% vs. 9.5%, P < 0.001). Path analysis support the evidence that EDS was directly linked to shift-work, HR and insomnia. Car accidents or falling asleep at work were directly associated with EDS and shift-work, and indirectly (via EDS) with HR and insomnia.
Conclusions: Development of EDS in shift-workers is not only due to work schedule, but also to the presence of sleep disorders. OSA and insomnia co-promote falling asleep during work and sleepiness-related car accidents.