Association between myopia and sleep duration among primary school students in minority regions of Southwest China: a school-based cross-sectional research

Objective To investigate the relationship between sleep duration and myopia among primary school students in minority regions of Southwest China. Methods The school-based, cross-sectional study was conducted from October 2020 to January 2021. All participants underwent a comprehensive ocular examination and completed a questionnaire on demographic characteristics, ophthalmological history and major environmental factors for myopia. Spherical equivalent (SE) and ocular biometric parameters were measured after cycloplegia, with myopia being defined as SE <=-0.5 D (Diopter). Multivariate regression models were used to examine the association of sleep duration with myopia, SE and axial length (AL). Results A total of 857 students from grades 2 to 4 were included in the analysis, of which 63.6% were myopic and 62.0% belonged to ethnic minorities. Boys had a slightly higher prevalence of myopia compared with girls (66.7% vs 60.6%, p=0.06). Myopic students had longer AL, deeper anterior chamber depth and thinner central corneal thickness compared with non-myopic students (all p<0.05). There was no significant association between sleep duration and myopia in both boys and girls (p=0.319 and 0.186, respectively). Moreover, girls with a sleep duration of 8-9 hour/day had higher SE and shorter AL compared with those with less than 8 hour/day of sleep (beta=0.41 and -0.32, respectively, all p<0.05). Conclusion This cross-sectional study did not find a significant association between sleep duration and myopia. However, it suggests that 8-9 hours of sleep per day may have a protective effect on SE progression and AL elongation in girls. Future studies with objectively measured sleep duration are needed to validate the findings.