Aerobic and Resistance Exercise Improve Patient-reported Sleep Quality and is Associated with Cardiometabolic Biomarkers in Hispanic and Non-Hispanic Breast Cancer Survivors who are Overweight or Obese: Results from a Secondary Analysis.

STUDY OBJECTIVES Poor sleep quality affects nearly one third of breast cancer survivors and is associated with insulin resistance. The purpose of this secondary analysis was to examine the effects of a 16-week exercise intervention on patient-reported sleep quality among breast cancer survivors and assess whether changes in patient-reported sleep quality were associated with cardiometabolic biomarkers. We explored Hispanic ethnicity as a moderator of the effects of exercise on patient-reported sleep quality. METHODS Breast cancer survivors who were overweight or obese were randomized to exercise (n=50) or usual care (n=50). The 16-week intervention included aerobic and resistance exercise. Patient-reported sleep quality [Pittsburgh Sleep Quality Index (PSQI)] and biomarkers of cardiometabolic health were assessed at baseline and post-intervention. Within- and between-group differences were assessed using general linear models repeated-measures ANOVAs and mixed-model repeated measure analysis, respectively. Associations between changes in PSQI and cardiometabolic biomarkers were computed using Pearson correlations. Linear mixed-models were used to evaluate effect modification by ethnicity. RESULTS Participants were 52±10.4 years old, and over half were of Hispanic ethnicity. As compared to usual care, PSQI global scores improved significantly in the exercise group (mean between group difference -2.2; 95% CI -3.2 to -0.6). Change in PSQI was inversely associated with changes in all cardiometabolic biomarkers (p<0.01) among the exercise group. Ethnicity was found to moderate the effects of exercise training on global sleep quality (p<0.001). CONCLUSIONS An aerobic and resistance exercise intervention effectively improved patient-reported sleep quality in breast cancer survivors. Hispanic ethnicity as a moderator showed greater improvement in patient-reported sleep indicating Hispanic versus non-Hispanic breast cancer survivors may derive larger sleep benefits.