Objective: To study the impact of sleep characteristics on myopia, among lower primary school students in Shanghai, so as to provide foundation for the prevention of the onset and development of myopia. Methods: A total of 636 students from the first and second grades of two primary schools in Jiading District, Shanghai, were selected through cluster random sampling for questionnaire surveys and ophthalmological examinations in October 2022. The Childrens Sleep Habits Questionnaire (CSHQ) was used to assess sleep quality at baseline. Ophthalmological examinations were conducted in October 2023(479), during which the students study time, screen time and outdoor activity time were monitored for twoweek, repeated twice. Generalized multivariable Logistic regression models and linear regression models were employed to examine the association between sleeprelated factors and myopia, as well as the strength of this association. Results: The baseline survey indicated a myopia prevalence of 18.58%, with 17.18% at followup. The average CSHQ total score was (51.58±4.44), and the average daily sleep duration was (9.43±4.84)h/d, with only 11.6% of participants meeting the recommended sleep sufficiency. Multivariable regression models indicated that insufficient sleep showed positive association with myopia (OR=1.64, 95%CI=1.05-2.56), while bedtime duration was significantly negative associated with myopia (OR=0.74, 95%CI=0.63-0.91, P＜0.05), adjusting for confounding factors. Inconsistency in bed rest time was a risk factor for myopia (OR=1.07, P<0.05), and the consistency of bed rest time, and wakeup time showed statistically significant correlations with SE (P<0.05). There was also statistically significant correlations between consistency in sleep time, bed rest time, and wakeup time with AL (P<0.05). Conclusions Insufficient sleep and bedtime duration are correlated with the onset and progression of myopia. It is critical to ensure sufficient sleep duration and regular sleep habits for children to reduce the occurrence of myopia in the primary school students.