Examining the 24-hour activity cycle in Irish adolescents: a repeated measures study

The 24-Hour Activity Cycle integrates the activity behaviours of physical activity, sedentary behaviour and sleep; each of which are associated with health and wellbeing outcomes in adolescents. The aim of this thesis was to examine the 24-Hour Activity Cycle in a sample of Irish adolescents tracked across three time points and investigate potential differences by gender and day type.

Repeated measures data was collected in two schools in Ireland as part of the Active School Flag Post-Primary Feasibility Study in autumn 2018, spring 2019 and autumn 2019. Activity behaviour data were derived from activPAL3 micro data. Separate repeated measures tests examined differences in the activity cycles across time points (i) across the whole week, (ii) across the whole week stratified by gender, (iii) on weekdays and weekend days, (iv) on weekdays and weekend days stratified by gender. Estimated Marginal Means and Post Hoc Pairwise Comparisons with Bonferroni adjustment were used to estimate and examine mean differences, the magnitude of effects were quantified using Cohen’s D and Hedges D.

Fifty four adolescents (mean age = 14.22 ± 1.59, 67% female) were included in the final analyses. The average 24-Hour Activity Cycle observed included: 39.13% sleep; 41.14% SB; 12.04% standing; 4.26% light-intensity physical activity; 3.24% moderate-to-vigorous physical activity. Less sleep (~20 minutes) was observed in spring compared to autumn time points; less moderate-to-vigorous (~15 minutes) and light intensity (~15 minutes) physical activity was observed in females than males; less sleep (~71 minutes), more sedentary behaviour (~75 minutes), less light-intensity physical activity (~12 minutes) and more moderate-to-vigorous physical activity (~13 minutes) was observed on weekdays than weekend days.

This research highlights the prevalence of sub-optimal activity behaviours in the sample. Health promotion efforts are required to enhance adolescent activity behaviour to enrich health and well-being, while seasonal, gender and day type specific interventions should be tailored for the greatest impact.