To look for an association between sleep deprivation and risk of accidental falls (AF) in children.A questionnaire was applied to two groups of children aged 1-14 years, encompassing children observed in an emergency room for AF (G1) and children attending health care visits (HV) (G2). Collected data included demographic characteristics, medical history, previous week's sleep pattern (PWSP), sleep duration and sleep pattern in the preceding 24 h, mechanism of fall, and injury severity.acute or chronic disease or exposure to drugs interfering with sleep. Statistical analyses included Fisher's exact test, Pearson Chi-square, Fisher-Freeman-Halton test, T and Mann-Whitney tests for independent samples, and multivariate logistic regression (α=5%).We obtained 1756 questionnaires in G1 and 277 in G2. Of those, 834 in G1 and 267 in G2 were analyzed. We found an increased risk of AF in boys (OR 1.6; 95% CI 1.2-2.4). After controlling for age, gender, summer holidays, parental education and profession, lack of naps and PWSP were associated with increased risk (OR 2.1; 95% CI 1.3-3.3 and OR 2.7; 95% CI 1.2-6.1). In 3-5 year-old children there was an association between AF and a shorter than usual sleep duration in the previous 24 h (p=0.02).To our knowledge, our study is the largest so far to assess the association between sleep deprivation and childhood injury. It evidences a protective effect of naps in children. Sleep duration of less than 8 h increases risk of AF. Pre-schoolers may be particularly susceptible to sleep deprivation.