Prevalence and predictors of sleep difficulty in a national cohort of women with primary breast cancer three to four months postsurgery

Context Mounting evidence suggests that many cancer patients suffer from sleep difficulty, but there is conflicting evidence regarding the prevalence and predictors of this adverse symptom. Objectives The present study investigated the prevalence and predictors of clinically significant sleep difficulty in women with primary breast cancer. Methods Danish women ( n =3343) with primary breast cancer completed the Pittsburgh Sleep Quality Index (PSQI) along with measures of depression, anxiety, physical activity/functioning, and health behaviors three to four months postsurgery. Data on disease status, treatment, and comorbidity were obtained from the Danish Cancer Cooperative Group and surgical departments, and information on sociodemographic factors and psychiatric history was obtained from Danish national longitudinal registries. Results More than half (57.9%) of the women reported clinically significant sleep difficulty (PSQI >5). Multiple logistic regression identified seven significant predictors of sleep difficulty in the full sample. In order of strength, these were the following: more depressive symptoms, poorer physical functioning, older age, higher levels of trait anxiety, consuming more cigarettes, having undergone lumpectomy, and lower levels of physical activity. Subgroup analysis found that more depressive symptoms and poorer physical functioning were the only two predictors that were significant in both pre- and postmenopausal women. Conclusion These findings indicate that a high proportion of women with breast cancer experience sleep difficulty. Depression and poorer physical functioning appear to be robust predictors of sleep difficulty, whereas other predictors may depend on sample characteristics, including menopausal status.