Late evening electric light exposure is associated with low sleep regularity in adolescents living in rural areas

In this study, we tested the prediction that sleep regularity would be lower in adolescents exposed to late evening electric light (LEEL) than in those without exposure to it. The Sleep Regularity Index was calculated based on actigraph recordings from adolescents living in rural communities in Argentina and Brazil that were either exposed to LEEL or not. The effect of the LEEL on sleep variables was tested using linear models considering sex and age, as well as accounting for the differences between countries. Sleep onset was delayed, sleep duration shortened, and Sleep Regularity Index was 4 [1-8] points lower in the group exposed to LEEL (p = .0176, eta² =0.13). Our results show that beyond sleep phase and duration, which are known to be affected by LEEL in this age group, sleep irregularity should also be considered as an important outcome variable when assessing the adverse effects of evening light on adolescents.