Abstract Background: Cancer-related cognitive difficulties (CRCD) is prevalent and distressing for breast cancer survivors and commonly co-occurs with insomnia. Although sleep tracking has become increasingly common in oncology settings, little is known about how sleep patterns influence cognition in cancer survivors. Therefore, we aim to characterize the associations between subjective and objective sleep continuity and cognition in breast cancer survivors with insomnia and CRCD. Methods: This analysis includes baseline data from a trial conducted among 260 breast cancer survivors with insomnia (Insomnia Severity Index score ≥8) and self-reported CRCD. This analysis is limited to trial participants who completed sleep tracking measures, including the Consensus Sleep Diary (CSD) and Actiwatch or FitBit smart watch (WA). Sleep continuity measures included wake after sleep onset (WASO), number of awakenings (NWAK), time spent in bed (TIB), total sleep time (TST), and sleep efficiency (SE). Subjective cognition was assessed by Functional Assessment of Cancer Therapy-Cognition Perceived Cognitive Impairment domain (FACT-Cog PCI), while objective cognition was assessed by Hopkins Verbal Learning Test-Revised (HVLT-R) Delayed Recall normed T-score. Multivariate linear regression modeling was used to explore associations between sleep continuity and cognition. All models included adjustments from covariates: chemotherapy use, cancer stage, race, and education. Results: Among 158 participants, the average age range was 57 28-83 and 21.5% were nonwhite. None of the sleep metrics collected from either the CSD or WA were significantly associated with subjective cognition (all p .05). In data collected by CSD, greater WASO was significantly associated with worse objective cognition (Coef. = -.243, p = .003, 95% CI -0.135, -0.028) and higher SE was significantly associated with better objective cognition (Coef. = .209, p = .011, 95% CI 0.054, 0.422). In data collected by WA, greater NWAK was significantly associated with worse objective cognition (Coef. = -.298, p = .010, 95% CI -0.294, -0.042). Conclusion: Measured and reported sleep continuity was not significantly associated with subjective cognition, but sleep fragmentation, measured by both sleep diary and smart watch, was significantly associated with worse objective cognition in breast cancer survivors with comorbid insomnia and CRCD. Interventions targeting sleep could be used to promote cognitive health during breast cancer survivorship. Citation Format: K. Lampson, X. Li, A. Yang, S. N. Garland, J. C. Root, T. A. Ahles, J. J. Mao. Association Between Sleep Continuity and Cognition in Breast Cancer Survivors: A Cross-Sectional Study abstract. In: Proceedings of the San Antonio Breast Cancer Symposium 2025; 2025 Dec 9-12; San Antonio, TX. Philadelphia (PA): AACR; Clin Cancer Res 2026;32(4 Suppl):Abstract nr PS1-05-18.
Lampson et al. (Tue,) studied this question.