Sleep has become increasingly studied in relation to development and maintenance of emotional symptoms across the lifespan, with significant implications for mental and physical health (Dahl, 1996; Gregory & Sadeh, 2012; Kortesoja et al., 2020). In particular, sleep disturbance is a transdiagnostic construct, listed as a symptom of various mental health disorders in the DSM-5-TR (American Psychiatric Association, 2022) and often appearing as part of the clinical presentation of several psychiatric disorders (Dahl & Harvey, 2007; Harvey et al., 2011). Sleep disturbance includes difficulties falling asleep and staying asleep throughout the night (Forrest et al., 2018). In youth specifically, sleep disturbance contributes to increased risk for depression, anxiety, and suicidality, and are often present among youth with other physical and mental health conditions as well (Chorney et al., 2007; Kearns et al., 2020). Sleep disturbance is also associated with irritability (Rubens et al., 2017), both of which are extremely common in adolescents (Karlovich et al., 2023). Yet there is limited research on the interplay between sleep and emotions, particularly on the unique associations of sleep disturbance with depression, anxiety, and irritability in youth. Despite prior research on single affective variables (e.g., links between sleep disturbance and anxiety), these associations have yet to be examined across a full range of emotional problems affecting youth. Given the transdiagnostic nature of sleep disturbance and frequent co-occurrence with mental health concerns, examining these unique associations is crucial to understanding the role of sleep in youth psychopathology.
Sleep Disturbance and Emotional Symptoms
Sleep-related symptoms are central features of major depressive disorders in DSM-5-TR (American Psychiatric Association, 2022). Sleep disturbance strongly contributes to the development and expression of depressive disorders in adults (Fang et al., 2019; Franzen & Buysse, 2008). Although much of the research on this topic has focused on adults, studies among children have found that sleep disturbance is associated with depression (Alvaro et al., 2013; Goldstone et al., 2020). Up to 73% of youth with Major Depressive Disorder have been found to experience sleep disturbance (Ivanenko & Johnson, 2008). Sleep disturbance has been found to predict depressive symptoms in youth, even after controlling for social anxiety (Armstead et al., 2019). Given the limited research on sleep disturbance and depression in youth, and their high prevalence in this period, more research is needed to understand their association.
Sleep and its relation to anxiety has become an important area of study. Young children with anxiety may be at a greater risk of experiencing problems related to sleep compared to their non-anxious peers (Alfano et al., 2010; Weiner et al., 2015). This includes sleep disturbance, which, when assessed on its own, has been found to be highly associated with anxiety (Brown et al., 2018; Cox & Olatunji, 2016). In clinical samples, up to 85% of parents of anxious youth have reported that their child also experiences clinically significant sleep disturbances (Alfano et al., 2010; Kendall & Pimentel, 2003). However, these studies generally do not account for the presence of comorbidities between anxiety and other affective variables, and the precise nature of the relationship between sleep disturbance and anxiety remains unclear.
Similar to sleep disturbance, irritability is a transdiagnostic nonspecific feature that is a primary or secondary symptom of numerous disorders (e.g., anxiety, depressive, and trauma and stressor-related disorders; Karlovich et al., 2023). Despite this commonality, there is limited research on the relationship between sleep and irritability. Several disorders characterized by severe irritability (e.g., bipolar disorders, Disruptive Mood Dysregulation Disorder) are also commonly linked to sleep disturbance (Delaplace et al., 2018; Harvey et al., 2015). Poorer sleep quality is associated with higher levels of irritability, as well as other emotional and behavioral problems (Rubens et al., 2017). Additionally, related bodies of research indicate that sleep disturbance predicts higher levels of aggression, violence, and delinquency (Clinkinbeard et al., 2011; Kamphuis et al., 2012). However, there has been limited research on the unique, specific association between sleep disturbance and irritability.
It is important to note that youth affective problems frequently co-occur (Ezpeleta et al., 2020). Particularly high comorbidity rates have been documented between anxiety and depressive disorders (for a review, see Cummings et al., 2014). The 2016 National Survey of Children’s Health showed that around 74% of youth with depression also had an anxiety disorder (Ghandour et al., 2019). Although researchers have examined sleep disturbance in relation to both anxiety and depression, many of these studies do not take into account the high correlations between these two problem areas (Chorney et al., 2007; Chu et al., 2019). Similarly, irritability is a transdiagnostic construct implicated in a range of mental health disorders in youth. Depression and irritability have also been found to be specifically associated with one another through various pathways, such as genetic and environmental risk factors (Vidal-Ribas Belil & Stringaris, 2021). Anxiety and irritability have been found to be uniquely linked (Cornacchio et al., 2016). It has been proposed that sleep problems play a key role in accounting for this association (Poznanski et al., 2018), although more research is needed.
Current Study
As summarized above, sleep disturbance has been found to be generally associated with depressed mood, anxiety, and irritability; however, there is also a significant amount of overlap between each of these variables. Given these patterns of high co-occurrence and correlation, the extent to which sleep disturbance is uniquely associated with these particular affective problems in youth remains unclear. It is important to identify these unique associations to better understand the specific role of each variable when controlling for co-occurring concerns. Research in this area could have important implications for the understanding, assessment, and treatment of sleep disturbance, depression, anxiety, and irritability in youth.
Accordingly, the current study seeks to fill this gap. We conducted a community-based study of youths ages 5–14 to examine associations among parent/caregiver-rated measures of child sleep disturbance, depression, anxiety, and irritability. We hypothesized that (a) sleep disturbance would be positively correlated with depression, anxiety, and irritability at the zero-order level; and that (b) sleep disturbance’s unique associations with depression and anxiety would be greater than its association with irritability in multiple linear regression analysis. The first hypothesis was made considering research reviewed above documenting sleep disturbances association with all three affective problems. The second hypothesis was made given that there appears to be relatively more evidence for sleep’s associations with depression and anxiety, and less for irritability; and given that the transdiagnostic nature of irritability (i.e., linked to anxiety and depression) may mean there is relatively little remaining variance associated with irritability through which it could be specifically associated with sleep disturbance. Finally, given the variations related to age (e.g., Solmi et al., 2022) and gender (e.g., Zahn-Waxler et al., 2008) in the development of emotional disorders, we examined these variables as covariates and moderators; however, considering the limited research on how these factors affect sleep’s associations with specific emotional problems, these analyses were considered exploratory.