Fig. 2. Multilevel perspectives on loneliness across historical time.

a, A multilevel perspective on loneliness according to which individuals are embedded in a greater social context (a couple or social network) and greater geographical contexts (local community, such as town or city; broader region, such as county or state; or country). Factors at all higher levels might influence individuals’ loneliness. At the same time, individuals influence higher-level factors directly (for example, through social contagion) and indirectly (for example, by being part of the composition of their respective population). b, Bidirectional associations between macro-level factors and loneliness might be explained by a cascade of cross-level indirect effects that unfold over time. In this example, an increase in residential mobility on the country level is assumed to lead to less contact with friends, which in turn increases individual-level loneliness. This individual-level increase might lead to increased loneliness in their social network (social contagion) and contribute to increased loneliness at the community, regional and country level.