INTRODUCTION: Loneliness is a significant global public health issue associated with a range of negative health outcomes. Men experiencing loneliness are at increased risk for depression
however, limited research has focused on mechanisms that explain the relationship between men's loneliness and depression. Existential isolation, the lack of feeling deeply understood by others, may be an important element that provides insight into how loneliness is related to men's depression over time, as evidence suggests that masculine norms may impair men's abilities to seek out help and experience emotional intimacy. The purpose of this study was to examine existential isolation as mediator between men's loneliness and depression over time. We hypothesized that the relationship between men's baseline loneliness and depression six months later would be mediated by their sense of feeling understood at three months. MATERIALS AND METHODS: An international community sample of men (n = 300) were recruited from the men's mental health website HeadsUpGuys and completed anonymous online surveys at three time points, including baseline, three months, and six months. The longitudinal design involved self-reported assessment of participants' loneliness, sense of feeling deeply understood, and depressive symptoms at all timepoints. RESULTS: The mediation model revealed men's perception of feeling deeply understood by others to be a significant temporal mediator of the association between loneliness and depression. CONCLUSIONS: Interventions that reduce or prevent men's loneliness and existential isolation may significantly reduce men's depression risk.