Depressive disorders can be observed in early childhood and are associated with significant concurrent and prospective impairment. Although young children demonstrate similar depressive behaviors as older children and adults, certain depressive behaviors, such as sadness and irritability, are more common in early childhood whereas other depressive behaviors, such as loss of pleasure and suicidal ideation, are much less common. However, little is known about day-to-day variations in common depressive behaviors and factors impacting those variations in early childhood. The current study examined the day-to-day variability and co-occurrence of two common depressive behaviors in young children, sadness and irritability, and predictors of their day-to-day change. Participants included 291 parents of preschool-aged children (ages 3-5).

Parents completed a baseline questionnaire assessing demographics, current emotional/behavioral problems, and functional impairment, and then completed an electronic daily diary for 14 days assessing the frequency of daily depressive behaviors, sleep quality, and parent-child relationship functioning. Results indicated that irritability and sadness frequently co-occurred during the same day and were concurrently and prospectively associated with parent-child relationship functioning but not sleep quality. Moreover, we observed between-person stability, but within-person variability, in children’s sadness and irritability across 14 days, and that this variability was moderated by several factors. With few exceptions, we observed greater between-person stability in sadness and irritability for older preschoolers, for males, and for children with overall better functioning (e.g., absence of less common depressive symptoms, fewer baseline psychiatric symptoms, lower baseline impairment, better parent-child relationship functioning and sleep quality). Importantly, our findings highlight stability of children’s sadness and irritability relative to peers and variability relative to their own mean sadness and irritability, as well as provide evidence regarding factors predicting the day-to-day stability or variability of these common depressive behaviors. Understanding daily variation in child depressive behaviors and factors predicting variation can identify at-risk children and provide targets for prevention and intervention, which is particularly crucial given that preschool depression predicts later depression and other psychiatric disorders.