Latent Profile Analysis of Sleep Patterns Among Late School-Age Children: Differences in Physical Activity, Purpose-Specific Smart Media Use, and Happiness

Objectives: Using latent profile analysis, this study classified children’s sleep patterns based on weekday and weekend bedtimes and wake-up times. It further examined group differences in physical activity, purposespecific smart media use, and happiness. Methods: The sample comprised 1,397 sixth-grade students from the 13th wave (2020) of the Panel Study on Korean Children. Latent profile analysis was conducted using weekday and weekend bedtimes and wake-up times. Group differences in physical activity, purpose-specific smart media use (i.e., learning, search, gaming, entertainment, and SNS), and happiness were examined using the BCH approach while controlling for sleep duration. Results: Sleep patterns were classified into three profiles: larks (<i>n</i> = 181), owls (<i>n</i> = 246), and intermediates (<i>n</i> = 970). Larks exhibited consistently early bedtimes and wake-up times on both weekdays and weekends, whereas owls maintained late schedules and showed pronounced social jetlag, particularly on weekends. Intermediates exhibited sleep–wake patterns between those of larks and owls. Larks engaged in significantly more physical activity than owls. Owls reported greater use of search, entertainment (e.g., music and video viewing), and SNS compared with larks. Finally, larks reported the highest levels of happiness, whereas owls reported the lowest. Conclusion: Children’s sleep patterns were clustered into larks, owls, and intermediates, with evening-type children demonstrating a marked tendency toward later bedtimes and wake-up times on weekends. Evening types also exhibited greater social jetlag, lower physical activity, higher engagement in problematic media use, and lower levels of happiness. These findings highlight the need for interventions that promote healthier lifestyles.