Relationships Among Physical Activity, Sleep Quality, and Chronotype in University Students

This study aimed to examine the relationships among physical activity levels, sleep quality, and chronotype among university students; determine whether physical activity and sleep quality differ across chronotype groups; and assess the predictors of sleep quality. Conducted using a cross-sectional and correlational design, the study involved 230 university students (127 men, 103 women; age: 21.13 ± 2.51 years). Data were collected using the International Physical Activity Questionnaire–Short Form, the Pittsburgh Sleep Quality Index, and the Morningness–Eveningness Questionnaire. No significant association was found between physical activity and sleep quality (ρ = −0.061, p = .360). Physical activity was weakly and positively associated with chronotype score (ρ = 0.144, p = .029), whereas chronotype score was weakly and negatively associated with sleep quality score (ρ = −0.233, p < .001). Physical activity and sleep quality differed across chronotype groups (χ² = 6.09, p = .048, ε² = .018; χ² = 7.33, p = .026, ε² = .023, respectively), with small effect sizes. However, pairwise comparisons showed no significant differences in physical activity, whereas sleep quality was poorer in the evening-type group than in the morning-type group. The regression model was significant (R² = .066, adjusted R² = .050, p = .004), and chronotype was the only significant independent predictor of sleep quality (β = −.207, p = .002). In conclusion, whilst a morningness-type tendency was weakly associated with higher levels of physical activity and better sleep quality, physical activity did not independently predict sleep quality. The potential effects of chronotype-sensitive interventions should be examined in controlled intervention studies.