A simplified schematic of the multilevel, moderated mediation (1-1-1) model with heterogeneous variance. Alcohol use, sleep duration, and tiredness are person-centered day-level repeated measures variables. Age group is person-level variable. The solid arrows from age group to ai, bi, and c′i indicate that the within-person associations among alcohol use, sleep duration, and tiredness may be moderated by age group, and the dashed arrows from age group to the residuals of sleep duration and next-day tiredness indicate that the variance of these residuals may also differ between age groups.