Many definitions of loneliness have been proposed in the 30 years that the topic has been the subject of clinical and academic investigation. Letitia A. Peplau and Daniel Perlman suggest that “loneliness is the unpleasant experience that occurs when a person’s network of social relations is deficient in some important way, either quantitatively or qualitatively.” It is critical to distinguish between isolation and aloneness and loneliness because loneliness is neither a cause nor a necessary outcome of physical isolation. There are three fundamental aspects of loneliness that research­ers across theoretical domains agree on: (1) it results from the perception of deficiencies in a person’s social relationships; (2) it is a subjective experience, not synonymous with social isolation; and (3) it is unpleasant and distressing. Loneliness ...