Predialysis fluid overload linked with quality of sleep in patients undergoing hemodialysis

Hemodialysis (HD) patients are exposed to dysregulated fluid balance which can lead to overhydration. Poor sleep quality and excessive daytime sleepiness are particularly common in these patients, however the relationship between fluid status and sleep quality and daytime sleepiness has not yet been studied. Therefore, the aim of this study is to evaluate the correlations between fluid status and sleep quality and daytime sleepiness in HD patients.

This cross-sectional study included 115 HD patients and 30 healthy control subjects from the HD center of Shanghai Ninth People's Hospital. Fluid compartments [total body water (TBW)], extracellular water (ECW)] and overhydration index (OH) were analyzed by multifrequency bio-impedance (BCM). Overhydration was defined as OH/ECW≥7%. HD patients were divided into an overhydration group and non overhydration group according to OH/ECW. Sleep quality was assessed by the Chinese version of the Pittsburgh Sleep Quality Index (PSQI), and excessive daytime sleepiness was evaluated by the Epworth Sleepiness Scale (ESS).

The prevalence rate of fluid overload in HD patients was 65.2%. Poor sleep quality (PSQI≥5) and excessive daytime sleepiness (ESS≥11) were significantly higher in HD patients compared with the healthy controls [6 (3, 10) vs.2.11 ± 1.59, p = 0.000; 3 (0, 6) vs.1.68 ± 1.07, p = 0.045]. Furthermore, the PSQI scores were higher in HD patients with overhydration (7.8 ± 4.5 vs. 4.8 ± 3.2, p = 0.000). The component scores 1, 2, 3 and 5 of the PSQI showed significant differences between the overhydration and non overhydration groups. The ESS scores did not show differences between the two groups (3.9 ± 4.1 vs. 3.3 ± 3.5, p = 0.508). OH was correlated with Systolic BP and Diastolic BP, and additionally was an independent predictor of poor sleep quality.

Fluid overload is significantly linked with poor quality of sleep in HD patients, however there is no association with excessive daytime sleepiness. Our study provides new insight into possible treatment strategies. Future studies should examine the effects of optimizing fluid status on quality of sleep.