Improved Sleep Quality Is Associated with Reduced Insulin Resistance in Cancer Survivors Undertaking Circuit, Interval-Based Exercise

Purpose: Cancer patients often experience poor sleep quality, typically induced by cancer-related treatments, a sedentary lifestyle, and psychological distress, leading to an increased risk of metabolic dysregulation such as obesity and insulin resistance. In this novel 16-week pilot study, we examined the effect of a circuit-based aerobic and resistance exercise intervention on self-reported sleep quality in breast, prostate, and colorectal cancer survivors and explored the association between changes in sleep quality and insulin resistance. Methods: Survivors of breast, prostate or colorectal cancers who were sedentary, overweight or obese (BMI>25.0 kg/m2) were randomized to exercise (n=60) or usual care (n=30). The 16-week intervention included supervised moderate-vigorous aerobic (65-85% of VO2max) and resistance (65-85% of 1-repetition maximum) exercise performed in a circuit, interval fashion three times per week. Patient-reported sleep quality and insulin resistance were assessed at baseline and post-intervention using Pittsburgh Sleep Quality Index (PSQI) and Homeostasis Model of Assessment (HOMA-IR), respectively. Mean changes in PSQI score that are negative demonstrate improvements in sleep. Between-group differences were determined using repeated-measures analysis of variance. Associations between changes in PSQI and insulin resistance were computed using Pearson correlations. Results: Participants were 63.2±10.8 years old, obese (87%), female (55%), and completed chemotherapy + radiation therapy (75%). Adherence to the intervention was 92% and the retention rate was 100%. Post-intervention, the PSQI global score improved significantly in the exercise group when compared to usual care (mean between-group difference, -2.7; 95% CI, -4.2 to -0.6). Change in PSQI was inversely associated with change in HOMA-IR (r=-0.91; p<0.01) among the exercise group. Conclusions: A circuit, interval-based aerobic and resistance exercise intervention improved patient-reported sleep quality in breast, prostate, and colorectal cancer survivors. Additionally, this exercise-induced improvement in sleep-quality may result in reduced insulin resistance.