Depression has been widely recognized as one of the most prevalent mental illnesses [1], characterized by persistent feelings of sadness, disinterest, and hopelessness [2]. Its prevalence in children and adolescents is relatively high [3], especially during the COVID-19 period [[4], [5], [6], [7], [8], [9], [10]]. For example, a seminal review indicated that the global prevalence of depression among this age group reached 25.2 % during the COVID-19 pandemic [9,10]. Furthermore, depression is the primary cause of illness and disability in this age group [11], which makes it a significant global health concern [12,13]. Children and adolescents who experience depression usually endure long-lasting effects that may extend into adulthood [14]. Notably, children and adolescents with depression had poorer mental and educational outcomes compared with non-depressed peers [15]. Chow et al. [16] found that children and adolescents with depression exhibited worse academic achievement while they were also likely to be less resilient to adversity and stress [17,18], and had poorer self-regulation abilities [19]. As a result, children and adolescents with depression may have significant negative impacts on quality of life[20,21].

Several interventions have been implemented to treat children and adolescents with depression, ranging from pharmacotherapy to psychotherapy [22,23]. However, the effects of these interventions varied between individuals [23]. Given that the effects of psychotherapy and other non-pharmacological interventions on depressive symptoms were moderate [24,25], and that higher levels of physical fitness and physical activity were linked to better cognitive function and resilience [[26], [27], [28], [29]], researchers have started paying more attention to modifying lifestyle behaviors via intervention [[30], [31], [32], [33]]. Such modifiable lifestyle behaviors encompass but are not limited to movement behaviors such as physical activity (PA), sedentary behavior including screen time (ST), and sleep [34]. For example, a meta-analysis reported positive effects of physical exercise in children and adolescents with depression [33]. There is also growing evidence suggesting that relatively high levels of PA can improve cognitive performance in children and adolescents [30]. Conversely, it has been observed that children and adolescents with unhealthy lifestyle behaviors such as excessive ST were linked to depressive symptoms [32] and psychological functioning [31]. Additionally, insufficient sleep or later sleep timing was linked to worse emotion regulation (an elevated likelihood of being diagnosed with a mood disorder) and poor academic achievement [35].

Traditionally, the influence of PA, ST, and/or sleep have been studied separately rather than considering their potential interactions [36]. Cognizant of the codependency among different movement behaviors, the Canadian 24-Hour Movement Behavior (24-HMB) Guidelines for children and adolescents (aged 5–17 years) were released [37]. It recommends ≥ 60 min/day of moderate-to-vigorous physical activity (MVPA), recreational ST ≤ 2 h/day, and 9–11 h of sleep per day (aged 5–13 years) or 8–10 h of sleep per day (aged 14–17 years) to maintain well-being [37]. Since the introduction of 24-HMB guidelines, a growing number of researchers have adopted this holistic perspective towards PA, sedentary behavior (including ST), and sleep [[38], [39], [40], [41], [42]]. Numerous studies have emerged indicating that healthy lifestyle habits, namely high levels of PA, low levels of ST, and adequate sleep time, bring significant advantages for the physical and mental well-being of children and adolescents [[43], [44], [45], [46], [47], [48]]. Recent studies on non-disabled individuals [49] and those with developmental disorders [39,50,51] have shown that both independent guidelines and integrated guidelines of movement behaviors were positively linked to academic performance, social function, and/or emotional function. Although several studies have investigated associations of adherence to 24-HMB guidelines with anxiety and depressive symptoms in children and adolescents [52,53]. To the best of our knowledge, there are no published studies investigating relationships of24-HMB guideline adherence with academic performance and psychological functioning in children and adolescents with depression. Extending our knowledge in this direction will be important to inform future interventions as well as clinical and public health guidelines to reduce depression-related health outcomes and to improve academic measures in this population.

With this context, this study examined whether adhering to 24-HMB guidelines is associated with better academic performance and psychological functioning in a nationally representative sample of children and adolescents with depression. In particular, we tested the hypotheses that for a sample of children and adolescents with depression in the US, (1) adherence to one or more 24-HMB guidelines is positively associated with academic performance, and (2) adherence to one or more 24-HMB guidelines is positively associated with psychological functioning.