The relationship between light exposure and bedtime/wake-up time during school days, holidays and long-stay camp period in Japanese children

Abstract

ABSTRACT This study aimed to clarify the situation of light exposure and examine the relationship between light exposure and bedtime/wake-up time during school days (SD), holidays (HD), and a long-stay camp period (CP) in Japanese children. After data cleaning, the final subjects were 29 children (10.2 ± 1.2 years old, 25 boys and 4 girls) who participated in paid long-term camp programs in the summers of 2019 and 2021. Data on light exposure, bedtime, and wake-up time were collected. The results of the comparison of the total high-intensity light exposure (HLE) hours for each survey period confirmed that HLE was high before the 18:00 zone in CP, and that for SD and HD were high after the 19:00 zone. Furthermore, the longer the total HLE hours before the 18:00 zone and the shorter those after the 19:00 zone were significantly earlier with both bedtime and wake-up time. These findings indicate that daytime and nighttime light exposure in children’s actual living environment is related to their bedtime and wake-up time, and that camping and going to school may be important factors to ensure children’s adequate daytime light exposure.