“Sleep-wake state discrepancy”: toward a common understanding and standardized nomenclature

People with insomnia reporting poorer sleep compared to estimates obtained from objective assessments is common across both research and clinical settings. Typically, individuals report less sleep and more wakefulness across a given sleep opportunity compared to that captured via objective methods (e.g. polysomnography) [1–3]. Many different terms have been used to describe this phenomenon since the 1970s [4], including but not limited to the following: sleep misperception [5], sleep-state misperception [6], sleep-state discrepancy [7], subjective-objective sleep discrepancy [3], sleep misestimation [8], and paradoxical- [9] and pseudo-insomnia [4]. The mechanisms underlying this phenomenon are not yet well understood [2] and require future research to inform developments in the diagnosis and treatment (or management) of the disorder. The aim of this letter is to facilitate such work by highlighting recent findings and proposing a new nomenclature to become standard practice for describing this phenomenon. Insomnia is regarded as a “subjective” disorder, for which individuals’ perceptions of sleep and daytime functioning form the basis of its assessment, diagnosis, and treatment. However, objective measurements of sleep may also hold an important role. Clinicians have anecdotally reported that discussing the discrepancy between perceived and objectively measured sleep can be therapeutic. Preliminary findings [10] support this anecdotal evidence, suggesting that personalized feedback about the discrepancy between self-report (sleep diary) and objectively measured (actigraphy) sleep reduced the discrepancy on subsequent nights in a group of 40 individuals with insomnia when compared to those who received no feedback [10]. However, there is limited knowledge about the mechanisms that underlie this phenomenon and the implications for the diagnosis and management of insomnia.