The demography of loneliness: Rethinking social connections in population research

Background: Loneliness is often treated as an individual or psychological experience, but it also reflects broader demographic and structural shifts. Population aging, declining fertility, migration, and shifting household arrangements have reshaped the ways individuals connect, care, and live. Despite its growing social relevance, loneliness remains under-theorized and under-measured in demographic research. Objective: This essay outlines why loneliness should be understood as both a consequence and a driver of demographic change. It examines how relational disconnection interacts with fertility, mortality, and migration across the life course, and offers a demographic framework for studying loneliness as a population process. Results: Loneliness emerges from demographic transitions (declining fertility, rising childlessness, increased longevity, and new migration regimes) that shape how people connect and care. In turn, loneliness influences demographic behaviors and outcomes, from reproductive intentions and union formation to survival, health, mobility, and return migration. These dynamics operate within cohorts and can accumulate across generations. Conclusions: Integrating loneliness into demographic models and data systems enhances the field’s ability to characterize population vulnerability and inform policy. Counting connection and disconnection alongside births, deaths, and moves improves our understanding on how people live and whether they thrive. Contribution: This essay contributes to demographic theory by articulating a framework that situates loneliness as both a cause and a consequence of demographic change. It bridges literatures on demography, well-being, and population dynamics to propose a demographic lens for understanding social disconnection across different contexts and life stages.