Circadian rhythms, characterized as intrinsic cycles with an approximate duration of 24 h, are significantly correlated with mood disorders (Daut and Fonken, 2019; Lorenz et al., 2019). Moreover, disruptions in externally imposed social rhythms have a substantial association with emotional dysregulation (Lin et al., 2020; Simpson et al., 2016; Yang et al., 2021). Consequently, to understand the intricate relationship between mood disorders and both endogenous and exogenous factors comprehensively, scholars recommend adopting the biological rhythms framework (Giglio et al., 2009). This concept refers to the cyclical patterns of life activities within a 24-h cycle, covering the sleep-wake cycle, rest-activity rhythms, social rhythms, dietary habits, energy metabolism, and hormonal fluctuations et al. (Abi-Dargham et al., 2023; Giglio et al., 2009).

Disturbances in biological rhythms are significantly linked to mood disorders. Notably, abnormalities in sleep/wake cycles, appetite, and social rhythms constitute key characteristics of conditions such as major depressive disorder (MDD) and bipolar disorder (BD). Contemporary research highlights a significant link between mood disorders and disruptions in biological rhythms. However, comprehensive studies focusing on the factors influencing these disturbances in depression remain scarce (Mondin et al., 2017; Ozcelik and Sahbaz, 2020; Pinho et al., 2016; Slyepchenko et al., 2019).

Anxiety ranks as the primary comorbidity in individuals with mood disorders, with epidemiological studies revealing that 45%–88% of those diagnosed also present with symptoms of anxiety (Kaufman and Charney, 2000; Merikangas et al., 2007; Pavlova et al., 2015; Saha et al., 2021). The comorbidity of depression and anxiety frequently exacerbates impairment and is commonly linked to a poorer prognosis (Katon et al., 2010; Kuzel, 1996). Patients suffering from depression, with a concurrent anxiety, exhibit significantly more psychopathological symptoms and have a higher tendency to terminate treatment prematurely compared to those with major depression alone (Brown, C. et al., 1996).

Some studies suggest a potential link between anxiety symptoms and disruptions in biological rhythms (Anyan et al., 2017; Walker et al., 2020). In an investigation conducted on healthcare professionals during the initial phase of the COVID-19 pandemic, Liu et al. observed that the aggregate BRIAN score exhibited a positive correlation with levels of anxiety, particularly in aspects related to sleep and social rhythms (Liu et al., 2022). Another survey conducted among Chinese college students revealed that disruptions in circadian rhythms were significantly associated with symptoms of anxiety (Tao et al., 2021). However, there is a deficiency in structured clinical assessments that delineate the relationship between anxiety symptoms and biological rhythms in patients with depression.

This study aimed to explore the association between anxiety symptoms and biological rhythms in patients with depression through structured clinical assessments, to identify factors contributing to these rhythms' disturbances, and to examine depression and anxiety's mediating roles in this context.