Mental Health and Well-Being of Undergraduate Nursing Students: A Cross-Sectional Study Using Canonical Correlation Analysis

Background: In recent decades, the relationship between mental health and well-being has been explored from many perspectives, with emphasis on the two-continua model of health in different contexts, with an emphasis on young higher education students. Both mental health and well-being are considered predictors of academic success. This study aims to analyze the relationship between mental health and well-being among first- and fourth-year nursing students. The sample consisted of 473 nursing students from a university in the central region of mainland Portugal. Methods: Data were collected using the short versions of the Depression, Anxiety and Stress Scale (DASS-21) and the Mental Health Continuum—Short Form (MHC-SF). Results: Canonical correlation analysis revealed a significant negative association between psychological distress and mental well-being. The first statistically significant canonical function (p < 0.05; Cr = 0.601) was primarily defined by depression (canonical loading = −0.992) in the distress group and emotional well-being (canonical loading = 0.948) in the well-being group. Redundancy analysis confirmed a significant interdependence: variables related to psychological distress explained 27.8% of the variance in well-being, while well-being variables explained 23.8% of the variance in distress. Conclusions: These results reinforce the two-continua model, highlighting the need to address both mental health and well-being throughout higher education.