Sleep Reorganization and Sustained Attention Following Group Nap Cessation in Japanese Preschoolers

Daytime napping is common in early childhood and gradually declines with age. This study examined sleep reorganisation following the cessation of routine group napping in Japanese preschool children and its association with sustained attention. This naturalistic pre-post study was conducted in a Japanese childcare center where routine group napping ended during the transition to the 4-year-old class. Nineteen children aged 48-59 months were included. Wrist actigraphy was recorded for 7 days before and approximately 3 weeks after nap cessation. Sleep variables were derived using the Sadeh algorithm and parent-reported sleep diaries. Sustained attention was assessed using a continuous performance test adapted for preschool children. After nap cessation, bedtime became earlier, time in bed increased, sleep onset latency decreased, and sleep efficiency improved. Nighttime sleep duration increased by 31.6 min, whereas nap duration decreased by 68.8 min, resulting in a 37.2-min reduction in total sleep time. Group-level changes in attentional performance were not statistically significant. However, reductions in nap duration were associated with increases in nighttime sleep duration (ρ = -0.49, p = 0.03), and increases in nighttime sleep duration were associated with fewer miss errors on the continuous performance test (ρ = -0.58, p = 0.02). Cessation of routine group napping was associated with a redistribution of sleep from daytime to nighttime without full compensation in total sleep time. Greater increases in nighttime sleep were associated with better sustained attention at the individual level. These findings support reconsidering uniform group nap policies and adopting more flexible childcare sleep practices.