Age and Sex Differences in Morningness/Eveningness Along the Life Span: A Cross-Sectional Study in Spain.

Work psychology has noted the importance of considering the temporal dimension of behavior in organizations. Given that society widely operates on a 24-hr schedule, it is important to know how circadian typologies are distributed in the general population. In this study, diurnal preference was analyzed among 4,175 Spanish participants (61.3% women), 12-59 years old, who completed the Composite Scale of Morningness (Smith, Reilly, & Midkiff, 1989). Several measurement models of the CSM were analyzed using exploratory structural equation modeling and confirmatory factor analysis. The bifactor model showed the best fit, with a general factor (morningness/eveningness) and three subfactors (morningness, morning affect, and time of retiring). The age and sex factorial invariance of the bifactor model were tenable at the latent variance-covariance level. Next, age and sex differences analysis indicated a progressive increase in morningness with age, but over 40 years old, men were more morningness oriented than women were. These results indicate that morningness/eveningness can be considered a multidimensional construct and that psychosocial factors must be considered when estimating the prevalence of morningness/eveningness in different populations or countries.