Insomnia I: Conceptualization and Etiology

The present chapter reviews the past and current theoretical conceptualizations of insomnia. As straightforward as it may seem, the definition of insomnia is complex and has evolved considerably over time. Several attempts have been made to refine the definition in terms of descriptive and diagnostic types and subtypes of insomnia. Alongside this pursuit, there have been advancements in understanding insomnia etiology and pathophysiology, resulting in 15 major human models of insomnia. The present chapter reviews (1) the definition of insomnia, (2) the major theoretical perspectives regarding the etiology and pathophysiology of insomnia, (3) the current evidence and implications of each perspective, and (4) promising directions for future research to better understand insomnia pathophysiology and its successful treatment.