A case-crossover study of sleep and childhood injury

Objective. To evaluate the association between sleep and wakefulness durati on and childhood unintentional injury. Study Design. Case-crossover study. Methods. Two hundred ninety-two injured children who presented at the Child ren's Emergency Center of Udine, Italy, or their parents were interviewed a fter a structured questionnaire. Information was collected concerning socio demographic variables, participant's habits, and injury characteristics, in cluding a brief description of the accident dynamics. Sleep or wakefulness status of the child was assessed retrospectively for each of the 48 hours b efore injury. For each child, we compared the 24 hours immediately before t he injury (hours 1-24; case period) with hours 25 to 48 (control period). N onparametric tests were conducted to compare the difference of sleep durati on between case and control periods. In addition, we conducted intrapersona l conditional logistic regression analyses and estimated relative risks (RR s) and 95% confidence intervals (CIs). Results. Overall, more children had longer hours of sleep during the contro l period than during the case period. However, this difference was signific ant for boys only. A direct association between injury risk and sleeping <1 0 hours was found among boys (RR: 2.33; 95% CI: 1.07-5.09) but not among gi rls (RR: 1.00; 95% CI:.29-3.45). This association was particularly strong a mong boys attending nursery school. We also found a direct association betw een injury occurring between 4 PM and midnight, and being awake for at leas t 8 hours before injury occurred (both sexes, RR: 4.00; 95% CI: 1.13-14.17) . Conclusions. Our findings show that inadequate sleep duration and lack of d aytime naps are transient exposures that may increase the risk of injury am ong children. These results suggest new prospects for injury prevention in childhood.