Terminology and definitions of sleep problems and disorders used in chronic musculoskeletal pain research: a scoping review with recommendations for future research

Sleep problems and disorders are prevalent in individuals with chronic musculoskeletal pain (CMP). Yet, previous reviews have struggled to draw precise conclusions due to inconsistent terminology and definitions of sleep problems and disorders. This review analyzed 225 studies to map terminology and definitions for sleep problems and disorders in CMP research. The included studies provided 326 definitions for 39 terminologies. The terminologies "insomnia," "poor sleep quality," and "sleep disturbance" were the most commonly used, though definitions varied significantly. Definitions of, for example, insomnia included different questionnaires, diagnostic criteria, and symptom-based assessments. This pattern was seen across most terminologies. This review also found overlapping definitions, such as the Pittsburgh Sleep Quality Index being used for 7 different terminologies. Inconsistent and overlapping use of terminologies and definitions creates confusion and potentially obscures sleep-pain links and the effectiveness of sleep interventions for CMP. This review makes recommendations for CMP researchers to choose the most appropriate terminology and definition for their research aim but also underlines the need for a consensus on terminology and measurement approaches. Standardizing terminology and definitions will enhance research accuracy, improve comparability, and strengthen the evidence base in the sleep-CMP field.