Effects of chronic diseases on health related quality of life is mediated by sleep difficulty in middle aged and older adults.

Middle-aged and older adults with chronic diseases are more likely to encounter sleep difficulty and have a reduced Health-Related Quality of Life (HRQoL), but there is little research on their possible mechanisms. Therefore, the main objective of this study was to explore how sleep difficulty mediates the impact of chronic diseases on the HRQoL of middle-aged and older adults. The survey data were from a cross-sectional study carried out in 2019 in Hangzhou, China. We used a multi-stage cluster random sampling method to recruit participants from seven districts in Hangzhou. Multiple regression was used to analyze the relationship between chronic diseases, sleep difficulty and HRQoL. And the mediate package in the R language was used to analyze the mediating effect. A total of 3,550 middle-aged and older adults were enrolled, including 2,273 patients with chronic diseases and 1,277 patients without them. Patients with chronic diseases had lower health utility values (β=-0.0084, P < 0.01) and were more likely to suffer from sleep difficulty (β = 0.5737, P < 0.001). After correcting for demographic and life characteristics, the mediation analysis results indicated that sleep difficulty mediated the relationship between chronic diseases and HRQoL (β=-0.0022, 95% Bca CI: -0.0034 -0.0014). Additionally, sleep difficulty influenced the association between chronic diseases and daily activities as well as pain (or discomfort) (β = 0.0083, 95% Bca CI: 0.0042-0.0111; β = 0.0162, 95% Bca CI: 0.0107-0.0225) in the analysis of the dimensions. Sleep difficulty partially mediated the relationship between chronic diseases and HRQoL, and primarily in the daily activities and pain (or discomfort) dimensions in middle-aged and older adults.