Associations of social jetlag with physical activity and sedentary behaviour in children and adolescents: A systematic review and meta-analysis.

Sleep and daytime movement behaviours occur co-dependently with each other within a finite 24 h day. Sleep parameters other than sleep duration, such as social jetlag and chronotype, have been linked to health problems and unhealthy behaviours among children and adolescents. Given the increasing number of studies examining sleep timing/chronotype and weight-related behaviours, including physical activity and sedentary behaviour, in the past decade, this systematic review and meta-analysis collated and evaluated the evidence on the relationships of social jetlag and chronotype with physical activity and sedentary behaviour among children and adolescents aged 3-17 years. Seven databases were searched on 16 March 2022, and 52 studies were identified as eligible for inclusion, 47 of which were suitable for the meta-analysis. A positive association was found between social jetlag and screen media use (r = 0.14, 95% CI: 0.04-0.24; I2  = 96%; p = 0.008). The morning chronotype was associated with a higher level of physical activity and a lower level of sedentary behaviour than the evening chronotype. No relationship was found between social jetlag and physical activity. The magnitude of heterogeneity among the included studies was high. Further experimental studies are urgently required to understand how circadian preference or misalignment affects activity behaviours. Interventions to promote an active lifestyle in young populations should consider their circadian preference, especially among individuals with the evening chronotype.