Physical Activity-Sleep Quality Relationships: Insights from Slovak Adolescents by Age and Gender

This study aims to provide insights into how physical activity is associated with sleep patterns in youth populations, in particular, Slovak adolescents, and how gender (boys vs. girls) and age (≤16 vs. ≥18) moderate this relationship, using an extreme-group comparison approach that excludes 17-year-olds to enhance contrast between developmental stages. Using a cross-sectional design, self-reported data were collected from 2504 (100%) high school students (aged 15–19; 45.6% boys, 54.4% girls) using the International Physical Activity Questionnaire-Short Form (IPAQ-SF) and the Pittsburgh Sleep Quality Index (PSQI). Participants aged 17 years were excluded from age-stratified analysis to create clearer separation between early/mid and late adolescence. The primary outcome was global sleep quality (PSQI > 5). Secondary outcomes included sleep duration and PSQI component scores. All other analyses (age- and gender-stratified comparisons and interaction models) were predefined as exploratory and hypothesis-generating to examine potential effect modification. Age-stratified analyses among girls showed that, within the low PA group, good sleep was reported by 37.7% of younger girls (≤16) and 28.6% of older girls (≥18). Among older girls, the proportion reporting good sleep increased to 49.8% in the high PA group (χ² = 29.16, p < 0.001). No consistent associations between PA and sleep quality were observed among boys; however, significant association was identified among younger boys (≤16 years), which was not observed in older boys. Logistic regression revealed a modest interaction between age and PA level in predicting sleep quality among girls (β = 0.346, p = 0.049), suggesting small age-dependent variation in the association. This effect should be interpreted cautiously given its borderline statistical significance. Component-level PSQI analyses showed that girls experienced higher rates of sleep disturbances (χ² = 91.40, p < 0.001), longer sleep latency (χ² = 26.71, p < 0.001), and greater daytime dysfunction (χ² = 79.90, p < 0.001). These findings provide region-specific evidence from Central and Eastern Europe and underscore the need for age- and gender-sensitive public health strategies targeting both physical activity promotion and better sleep outcomes, given their observed associations.