1035 Roles of Sleep Coregulation in Longitudinal Neuroendocrine Functioning Among Patients with Colorectal Cancer and Their Spouses

Abstract Introduction Sleep disturbance in adults with cancer and their caregivers is a significant yet understudied health concern. Couples often influence one another’s sleep through psychological and physiological aspects of their relationship. This study examined how sleep coregulation between patients and their spousal caregivers relates to changes in their neuroendocrine functioning over time. Methods Patients with colorectal cancer and their spouses (137 dyads; 56.15 years old, 32.9% female patients, 69.1% advanced cancer, 7 months post-diagnosis) completed questionnaires assessing relationship duration, social constraint, and relationship quality with the partner at the initial assessment (T1). Participants also completed 14 consecutive days of sleep logs at T1. Using continuous-time structural equation modeling, we calculated sleep coregulation indices (SCIs), reflecting the extent to which one partner’s sleep efficiency (SE) on a given day predicted the other partner’s SE on subsequent days. Participants provided saliva samples 2-4 times daily for 7 days at T1 and one year later (T2) to derive diurnal cortisol slopes at T1 and T2. Covariates included age, BMI, and T1 cortisol slope. Results Both patients and caregivers reported poor sleep efficiency (M=82.9%). Only caregivers exhibited significantly flatter diurnal cortisol slopes (worse neuroendocrine functioning) at T2 compared with T1 (p<.003). Patients’ steeper (healthier) T2 cortisol slope was associated with higher relationship quality (p=.01). It also tended to be negatively associated with greater SCI when their caregivers’ SE predicted patients’ subsequent SEs, whereas it was positively associated with greater SCI when patient’s own SE predicted their caregiver’s subsequent SEs (p≤.063). In contrast, caregivers’ steeper T2 cortisol slope was negatively associated only with their greater dependence on the patient (p=.006). Conclusion Findings provide preliminary support that high-quality relationships and synchrony in caregivers’ sleep patterns may benefit patients’ neuroendocrine functioning over time, whereas greater relationship dependency may be detrimental for caregivers. Results underscore the need for dyadic sleep interventions that jointly address patients and their sleep-partner caregivers and incorporate dyadic coping skills to promote healthy interdependence and relationship satisfaction. Larger studies investigating additional interpersonal and medical factors influencing sleep coregulation in couples coping with cancer are warranted to guide future research and clinical practice. Support (if any) R01NR016838