A mediation analysis of the relationship between fatigue, sleep disturbance, and quality of life among cancer patients

Cancer-related fatigue (CRF) and sleep disturbance are common and debilitating symptoms among cancer patients, often leading to reduced quality of life (QoL). This study investigated the interrelationships among fatigue, sleep disturbance, and QoL in cancer patients, and examined whether sleep disturbance mediates the relationship between fatigue and QoL. A cross-sectional study was conducted involving 369 adult cancer patients attending the National Oncology Centre in Oman. Participants completed validated Arabic versions of the Functional Assessment of Cancer Therapy–Fatigue (FACIT-Fatigue), the Pittsburgh Sleep Quality Index (PSQI), and the Functional Assessment of Cancer Therapy–General (FACT-G). Descriptive statistics, Spearman’s correlation coefficients, and Structural Equation Modeling (SEM) with bootstrapping were used for data analysis. The mean global PSQI score was 9.2 (SD = 4.2), indicating poor sleep quality. The average fatigue score was 22.7 (SD = 13.0), and the mean overall QoL score was 69.0 (SD = 18.5). Fatigue and sleep disturbance were significantly negatively correlated with all QoL domains. SEM analysis demonstrated a significant direct effect of fatigue on QoL (Estimate = 0.312, p < 0.001) and an indirect effect mediated by sleep disturbance (Estimate = 0.085). Sleep disturbance also had a strong negative effect on QoL (Estimate = –4.689, p < 0.001). These findings highlight the need for integrated, symptom-focused care strategies to manage fatigue and sleep disturbance and improve QoL in cancer patients. Implementing early screening and targeted interventions may enhance clinical outcomes and promote long-term patient well-being.