Dual associations of post-sleep and pre-wake light-at-night (LAN) exposure with myopia in children and adolescents.

OBJECTIVE

To analyze the association between indoor light at night (LAN) exposure with myopia in children and adolescents.

METHODS

A cross-sectional survey was conducted in 2023 involving 872 students aged 6-14 years in Beijing, China. Portable photometers continuously measured indoor LAN exposure over four nights. Log-binomial regression explored the association between LAN with myopia. Iso-temporal Substitution Model (ISM) investigated how reallocating exposure durations at different LAN levels affects myopia.

RESULTS

Compared to the overall ≤1 Lx LAN group, the risk of myopia increased during the 1h post-sleep and 2h post-sleep in the (1,10] lx and >30 lx group and during the 4h post-sleep in the >30 lx group. In contrast, myopia risk decreased during the 2h pre-wake in the (10,30] lx group and during the 1h pre-wake in the (10,30] lx and >30 lx group. Replacing bright light with dim light 2h post-sleep, and dim light with bright light 2h pre-wake, may help reduce myopia risk. The associations were more pronounced in girls and the group with ideal healthy lifestyles.

CONCLUSION

LAN cycle has a dual association with myopia. Promoting healthy LAN environment, with dim light (≤1 lx) post-sleep and soft light (10-30 lx) pre-wake, may contribute to myopia prevention.