Anxiety and sleep quality in the undergraduate stress–depression link: A moderated mediation study

First-year undergraduate students are particularly vulnerable to stress-related anxiety and depression, and they generally exhibit poorer sleep quality compared with other student populations. While anxiety is known to explain how stress contributes to depression, its specific mediating role in the context of undergraduate-related stress remains unclear. Moreover, although poor sleep is highly prevalent in this group, its potential to exacerbate or buffer these mental health risks has been largely overlooked. To investigate these issues, this study examined whether anxiety acts as an intermediary in the link between undergraduate stress and depressive symptoms and whether sleep quality influences the intensity of these connections. This observational study included a final sample of 102 first-year psychology students (Mage = 19.75 ± 1.76 years) who completed assessments measuring sleep quality, stress, anxiety, and depression. Descriptive statistics, correlational analyses, and path analyses were conducted to determine the prevalence of poor sleep, variable associations, and the mediating and moderating roles of anxiety and sleep quality. Poor sleep quality was highly prevalent (61.8%) and significantly correlated with undergraduate stress (ρ = 0.42, p < .01), anxiety (ρ = 0.46, p < .01), and depression (ρ = 0.44, p < .01). Anxiety significantly mediated the relationship between undergraduate stress and depression (indirect effect = 0.23, 95% CI 0.09, 0.38). Additionally, sleep quality moderated the anxiety–depression pathway (β = 0.04, p < .05) but not the stress–anxiety or stress–depression pathways. Anxiety plays a central role in linking undergraduate-specific stress and depression in first-year students. Crucially, poor sleep quality selectively intensified the association between anxiety and depressive symptoms, placing students with both elevated anxiety and poor sleep at high risk. Early, dual-targeted interventions may help prevent long-term depressive consequences. Future research should clarify temporal pathways and identify which stress and sleep components best predict depressive symptoms.