This book examines loneliness as a complex biopsychosocial phenomenon. Synthesizing research from psychology, communication, sociology, and public health, this volume provides a comprehensive framework for understanding the antecedents, outcomes, and potential remedies for loneliness in the 21st century. The book begins by conceptualizing loneliness as distinct from social isolation and solitude, grounding its analysis in foundational theories such as attachment theory, socioemotional selectivity, and evolutionary psychology. Epidemiological data are presented to illustrate the global prevalence and demographic distribution of loneliness, with attention to measurement challenges and public health implications. Subsequent chapters explore the multifactorial origins of loneliness, including personality traits, attachment styles, life transitions, and structural conditions such as socioeconomic status, urbanization, and technological change. The consequences of loneliness are examined in depth, encompassing psychological distress, physical health deterioration, cognitive decline, and broader societal costs including diminished social trust and increased healthcare burden. A critical analysis of digital technologies—including social media and artificial intelligence—addresses their dual role in both mitigating and exacerbating loneliness. The book evaluates emerging forms of digital companionship and considers ethical concerns surrounding authenticity, dependency, and data privacy. The volume concludes with a synthesis of evidence-based interventions, ranging from individual therapies and relational approaches to community programs and policy-level strategies. It highlights promising innovations in telehealth, app-based support, and urban design, while identifying conditions under which interventions are most effective.

Kory Floyd is professor and chair of human development at Washington State University, as well as a licensed mental health counselor. His research focuses on the communication of affection in close relationships and its effects on stress and physiological functioning. He has written 16 books and over 100 scientific papers and book chapters on the topics of affection, emotion, family communication, nonverbal behavior, and health. He is a Fellow of the International Communication Association and a former editor of Communication Monographs and Journal of Family Communication. His work has been recognized with the Charles H. Woolbert award, the Bernard J. Brommel award, and the Mark L. Knapp award from the National Communication Association, the Distinguished Scholar Award from the Western States Communication Association, and the Early Career Achievement award from the International Association for Relationship Research. Professor Floyd received his undergraduate degree from Western Washington University, a master’s degree from the University of Washington, a master’s degree from the College of William and Mary, an education specialist degree from the University of West Georgia, and his PhD from the University of Arizona.