Abstract
Light exposure is a major regulator of wakefulness and sleep. Low exposure to natural outdoor light and high exposure to screens are proven disruptors of sleep and circadian rhythms. During the first lockdown in March-May 2020 in France, some behaviors may have been modified including the use of screens, exposure to natural light and sleep schedules. We aimed at describing and studying relations between light exposure and sleep modifications in children aged 8–9 years from the ELFE and EPIPAGE-2 national birth cohorts included in the SAPRIS study conducted during the 2020 lockdown period. We included 3513 children aged 8–9 years (52 % boys) with complete available data on light exposure, sleep and both parental and child confounders. Mean daily natural outdoor light exposure was 2h39 ± 2h05 and mean daily screen time exposure was 4h00 ± 2h53. Sleep duration was increased and decreased in 35.4% and 12.1% of the children, respectively while sleep difficulties appeared or increased in 21.5% of them and decreased, disappeared or stayed stable in 18.5%. After accounting for confounding factors, we showed an association between increasing screen time and decreased sleep duration in the child but no association between screen time and changes in sleep difficulties nor between duration of natural light exposure and changes in sleep (duration and quality). Our study provides arguments in favor of limiting screen exposure in children for a better sleep, especially in specific periods such as lockdown.