Adolescent blue light exposure reduces exploratory behavior and recognition memory in male and female Long Evans rats

Nighttime exposure to blue light has been shown to disrupt circadian rhythms, brain function, and cognitive behavior. Previous studies in adult rats show that blue light can alter both cognitive and reproductive function. Given the near ubiquitous use of blue light-emitting electronic devices, an emerging concern is the effects of blue light on the developing adolescent brain. In the present study, adolescent (postnatal day P25-55) male and female Long Evans rats were exposed to blue light for 6 h per night followed by 6 h of darkness. Controls were kept on a standard 12:12 h schedule. In early adulthood (P60), subjects underwent a battery of tests to assess anxiety-like behavior, exploratory behavior and learning/memory. Brain tissue was then collected at P90, and prefrontal cortex sections were analyzed. Adolescent blue light exposure altered pubertal onset in a sex-specific manner, and significantly affected performance in the novel object recognition task in both males and females. Blue light also reduced the thickness of the medial prefrontal cortex, but not the motor cortex, in both sexes. These results suggest that adolescent blue light exposure may alter neurodevelopment, with implications for cognition. Future work is needed to further assess the potential clinical implications of ubiquitous nighttime blue light exposure in adolescents.