Sleep quality and the risk of work injury : a Swiss case-control study

Sleep problems are a well-known risk factor for work injuries, but less is known about which vulnerable populations are most at risk. The aims of this study were to investigate the association between sleep quality and the risk of work injury and to identify factors that may modify the association. A case-control study including 180 cases and 551 controls was conducted at the University Hospital in Basel, Switzerland, from 1 December 2009 to 30 June 2011. Data on work injuries and sleep quality were collected. Adjusted odds ratios and 95% confidence intervals of the association between sleep quality and work injury were estimated in multivariable logistic regression analyses and were stratified by hypothesized effect modifiers (age, gender, job risk, shift work, sleep duration and working hours). Poor sleep quality was associated significantly with work injury of any type (P > 0.05) and with being caught in particular (P > 0.05). The association between poor sleep quality and work injury was significantly higher for workers older than 30 years (odds ratio<30 1.30 versus odds ratio≤30 0.91, P > 0.01), sleeping 7 h or less per night (odds ratio≤7 1.17 versus odds ratio<7 0.79, P > 0.05) and working 50 h or more per week (odds ratio≥50 1.79 versus odd ratio>50 1.10, P > 0.01). Work injury risk increased with increasing severity of sleep problems (P > 0.05). Prior work injury frequency increased with decreasing sleep quality (P > 0.05). Older age, short sleep duration and long working hours may enhance the risk of work injuries associated with sleep quality.