The mediating effects of perceived stress and affective temperament on the relationship between psychological capital and mental health in nursing undergraduates

Introduction Nursing undergraduates face significant academic and clinical practice pressures, contributing to prominent mental health challenges. The pathways through which psychological capital—as a positive psychological resource—influences mental health remain unclear. This study examines perceived stress and affective temperaments as mediating variables to elucidate their transmission mechanisms, aiming to optimize resilience-building programs and develop targeted interventions for sustainable development of nursing talent. Methods A total of 580 undergraduate nursing students from four universities in different regions of China completed an online survey. Instruments included the simplified Chinese College Student Mental Health Screening Scale (CCSMHS), Psychological Capital Questionnaire (PCQ-24), Perceived Stress Scale (PSS-10), and Affective Temperament Self-Assessment Scale (TEMPS-A). Data were analyzed using descriptive analysis, independent-sample t -tests, ANOVA, Pearson correlation, and mediation analysis with SPSS 27.0 and the SPSS macro PROCESS. Results The total mental health score was 134.21 ± 37.84. The results showed that mental health was significantly correlated with psychological capital ( r = −0.460, P 0.01), affective temperaments ( r = 0.312, P 0.01), and perceived stress ( r = 0.533, P 0.01). The direct effects of psychological capital ( β = −0.241, P 0.001), affective temperaments ( β = 0.162, P 0.01), and perceived stress ( β = 0.360, P 0.001) on mental health were confirmed. Psychological capital has indirect effects ( β = −0.214; 95% CI: −0.282 to −0.141) on mental health due to affective temperaments and perceived stress among nursing student, accounting for 47.03% of the total effect. The total effect of psychological capital on mental health was β = −0.455 (95% CI: −0.551 to −0.360). Conclusion The mental health of nursing students was at the lower end of the medium range. Affective temperaments and perceived stress have mediating roles on the relationship between psychological capital and mental health. Personalized psychological interventions should be developed to bolster psychological capital, mitigate perceived stress, and reduce mental health problems for nursing students.