Poor Sleep Quality Predicts Decline in Physical Health Functioning in Patients with Coronary Heart Disease and Moderating Role of Social Support.

Although sleep problems are common among patients with coronary heart disease (CHD), there is a lack of prospective research examining its influence on health consequences over time. This study investigated whether poor sleep quality predicted patients' decline in physical health functioning over 6 months and whether social support buffered its detrimental effect. Participants were 185 patients with CHD, who completed measures of sleep, psychosocial characteristics, and physical health functioning at baseline and 6 months. Hierarchical regression analyses were conducted to examine whether global sleep index and its subscales, including sleep efficiency, perceived sleep quality, and daily disturbances (sleep disturbances and daytime dysfunction), predicted the decline of physical health functioning at 6 months. Social support was examined for its moderating effect in buffering the negative influence of poor sleep quality on physical health functioning over 6 months. Findings showed that poorer global sleep index, especially subscales of daily disturbances and lower sleep efficiency, significantly predicted greater decline of physical health functioning at 6 months, even after adjusting for covariates, including baseline functioning and depression. Moreover, social support was found to buffer the detrimental impact of poor sleep quality, especially low sleep efficiency, on 6-month physical health functioning. Findings suggest that improving sleep quality for patients with CHD may be promising to facilitate their long-term health maintenance.

Measurement Structure of the Pittsburgh Sleep Quality Index and Its Association with Health Functioning in Patients with Coronary Heart Disease.

Research on the underlying structure of sleep measures in patients with coronary heart disease (CHD) is lacking. Existing research on sleep and health outcomes primarily focused on only one dimension of sleep (e.g., sleep duration), leaving other aspects unexamined. To address this gap, this study examined the measurement structure of Pittsburgh Sleep Quality Index (PSQI) and its associations with health-related quality of life among CHD patients. Participants were 167 CHD patients from a cardiac wellness program. Confirmatory factor analysis revealed that the two-factor structure with sleep efficiency and perceived sleep quality best fitted the data. Concurrent validity analyses with structural equation modeling showed that, when considered simultaneously, perceived sleep quality, but not sleep efficiency, was significantly associated with emotional, physical, and social quality of life. Findings demonstrated that the PSQI consists of two moderately correlated factors that are differentially associated with separate health domains in cardiac patients.