Light-at-night and short sleep: a synergistic dual threat to myopia in children and adolescents

Purpose To determine the independent and joint effects of nighttime light exposure and sleep duration on childhood myopia and quantify their interaction. Methods This cross-sectional study enrolled 2630 first-grade and 1941 seventh-grade students from the Anyang Eye Study. Questionnaires collected data on sleep lighting, fluorescent light exposure, sleep duration and demographic characteristics; all underwent ophthalmic examinations, cycloplegic autorefraction and ocular biometry using an IOL Master. Multivariate logistic regression was used to assess associations and additive interaction was evaluated using relative excess risk due to interaction (RERI), attributable proportion (AP). Results In the overall population, students sleeping with lights on and with insufficient sleep had the highest myopia rate (48.41%). In first graders, light on with insufficient sleep was significantly associated with myopia (OR = 2.980, 95% CI: 1.801 to 4.931, p<0.001). A similar trend was seen in seventh graders (OR=1.802, 95% CI 1.189 to 2.730, p=0.006). Positive additive interaction was found (overall RERI=0.834, AP=0.407). The association of sleeping with lights on with myopia was greater in females, lower grades and those with myopic parents; however, in females, the AP estimate for the additive interaction exceeded zero (AP=0.721, 95% CI 0.238 to 1.203), suggesting that this subgroup may be particularly susceptible. Conclusions Sleeping with lights on and insufficient sleep are independently associated with myopia and exhibit a positive additive interaction. The findings suggest that improving the nocturnal light environment and ensuring adequate sleep might be important for myopia prevention and control.