Association between sleep disorders and functional status in individuals with chronic obstructive pulmonary disease: a systematic review

Sleep disorders and reduced functional status are common in individuals with chronic obstructive pulmonary disease (COPD) and negatively impact health outcomes. However, their association remains unclear. This systematic review aimed to synthesize evidence on the association between sleep disorders and functional status in individuals with COPD, and identify the instruments, variables, and diagnostic criteria used to assess these outcomes. A comprehensive search was initially conducted in 2021 and updated twice, with the final search performed on July 11, 2025, in CINAHL, Cochrane Library, EMBASE, LILACS, MEDLINE, PEDro, SciVerse Scopus, and Web of Science. Reporting and methodological quality were assessed using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist and the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Fifteen studies were included, totaling 2297 individuals with COPD. Sleep disorders were assessed using six diagnostic methods, and functional status was evaluated using three approaches. Twelve studies met 50–80% of STROBE criteria, and three met > 80%. Methodological quality was fair in 73%, good in 13% and poor in 13% of the studies. Sleep disorders were weakly to moderately associated with functional status, including field walking tests, maximal exercise capacity, and time spent in physical activity > 1.5 METs. Moderate methodological quality suggests a weak-to-moderate association between sleep disorders and functional status in individuals with COPD. Further high-quality studies using validated instruments and study designs tailored to minimize bias are warranted to clarify this relationship and enhance its clinical applicability.