Validation of a three-dimensional model about sleep: Habits, personal factors and environmental factors

OBJECTIVES The present study aims to test the factor structure of two sleep questionnaires and their internal consistency in a sample of adolescents and their respective parents and to evaluate the validity and robustness of a three-dimensional model about sleep, addressing nine subcategories related to sleep habits, personal and environmental factors. METHODS Participants were 654 adolescents from Portuguese schools, who completed "My Sleep and I" questionnaire, and 664 parents who completed "My child׳s sleep" questionnaire; to them confirmatory factor analysis was applied. RESULTS Confirmatory factor analysis indicate that a nine-factor model has better fit indices compared with the others tested models for both samples (adolescents: χ (2)/df (Chi-square/degrees of freedom)=2.59, Comparative Fit Index (CFI)=.82, Goodness-of-Fit Index (GFI)=.92, Root Mean Square Error of Approximation (RMSEA)=.049, Expected Cross-Validation Index (ECVI)=1.416; Parents: χ (2)/df=2.89, CFI=.85, GFI=.91, RMSEA=.053, ECVI=1.528). Moreover, the comparison of the models through Δχ (2) index (chi-square difference between rival models) indicates a better fit for this model, Δχ (2) (24)=186.5, p<.001 for adolescents and Δχ (2) (24)=209, p<.001 for parents. Also, the three second-order factors have good internal consistency, convergent and discriminant validity for all factors in both samples. CONCLUSIONS Results postulate that the three factors and their nine subcategories account for correlations between sleep habits, self-perceptions and knowledge about sleep.