To Örebro University

Background: Alterations in habitual sleep/wake patterns (SWP) of women with breast cancer and their informal caregivers may be concurrently exacerbated and co-vary during the patient’s treatment. Taking into consideration the complexity of mechanisms interfering with a care dyad’s sleep, the current study set out to longitudinally explore SWP of patientcaregiver dyads in the context of adjuvant chemotherapy (CTh) for breast cancer.

Material and Methods: In this descriptive, observational, repeatedmeasures dyadic study, 48 newly diagnosed women receiving outpatient adjuvant CTh for early stage breast cancer (stage I−IIIA), and their nominated primary informal caregiver completed self-reported sleep measures at pre-treatment (week prior to CTh), post-CTh cycle 1, post- CTh cycle 4, and approximately 30 days after CTh (total of 6 cycles received). Multivariate hierarchical linear modelling (MHLM) techniques were implemented to analyse dyadic sleep data.

Results: Prior to CTh, 65% of dyads consisted of at least one poor sleeper, a rate further increasing to approximately 88% at CThC4. MHLM revealed curvilinear trajectories for most of dyads’ sleep/wake parameters that nevertheless reached significance (p <. 05) only for patients. In both groups, sleep/wake impairment reached its peak at mid-treatment (CThC4); yet, patients consistently reported significantly more sleep problems than their carers. Partial convergence also emerged as suggested by positive correlations and no between-groups differences in daily disturbance, daytime napping duration (NAPTIME), total sleep time, and overall sleep/ wake disruption at pre-treatment. At CThC4, rates of change in sleep latency and NAPTIME were alsosimilar.

Conclusions: The current study is one of the first studies to show that a dyadic approach in the assessment of SWP in patients with breast cancer and their carers is a promising method to enhance exploration of potentially concurrent sleep-impairment. Replication of the current findings in future dyadic sleep research is an absolute priority. Meanwhile, clinicians will need to engage in concurrent systematic and on-going sleep assessments that synthesise and contrast data to establish a care dyad’s level of sleep quality.