<i>Couples Sharing Sleep and Sickness</i> : Dyadic Sleep‐Wake Patterns, Health Consequences, and Intervention Efficacy in Cancer Patient‐Caregiver Dyads—A Systematic Review and Preliminary Meta‐Analysis

BACKGROUND: Sleep disturbances are prevalent among cancer patient-caregiver dyads, yet their interdependent sleep patterns remain understudied. Therefore, this systematic review aimed to synthesize evidence on dyadic sleep-wake patterns, health consequences (physical, psychological, and relationship health), and the effectiveness of dyadic intervention (intervention delivered to both members in the dyad) on sleep outcomes in cancer patient-caregiver pairs. METHODS: Following JBI guidelines, we searched five databases (Cochrane Library, PubMed, CINAHL, Web of Science, EMBASE) for studies assessing dyadic sleep patterns, health outcomes, and interventions in adult cancer dyads. Quality of observational studies was evaluated using the JBI critical appraisal tool for analytical cross-sectional studies. Quality of randomized controlled trials (RCTs) was evaluated using the Cochrane Collaboration's Tool for Assessing Risk of Bias Version 2.0. Narrative synthesis addressed: (1) dyadic sleep-wake patterns, (2) health consequences, and (3) sleep outcomes measured in dyadic interventions. Random-effects meta-analyses pooled sleep outcomes from interventions. RESULTS: From 3862 screened studies, 28 were included (19 observational, 9 interventional). Our synthesis of observational studies revealed that sleep disturbances were highly prevalent and co-occurring within dyads, with members showing moderate-to-strong concordance in sleep quality (r = 0.31 to 0.68, median r = 0.45). Actor effects (one's own sleep affecting one's own health) were consistently strong across physical health (β = 0.22-0.57), psychological health (β = 0.22-0.57), and relationship health (β = 0.03-0.24). Partner effects (one partner's sleep affecting the other's health) ranged from β = 0.15 to 0.48 across physical and psychological outcomes. For dyadic interventions, mindfulness-based approaches were most tested, though family resilience and acceptance/commitment therapies also showed promise. However, only one study explicitly targeted sleep with a dyadic adaptation of Cognitive Behavioral Therapy for Insomnia. A meta-analysis of nine studies (128 patient participants) showed a small statistically significant effect (SMD = -0.33, 95% CI = -0.62 to -0.04, p = 0.02). However, when limiting the analysis to three RCTs with 74 couples, dyadic interventions yielded a non-significant effect on decreasing patients' sleep disturbances (SMD = -0.22, 95% CI = -0.56 to 0.12). For caregivers, the full meta-analysis showed a moderate effect (SMD = -0.42, 95% CI = -0.68 to -0.16, p = 0.002), and the RCT-only analysis remained significant but attenuated (SMD = -0.36, 95% CI = -0.71 to -0.02, p = 0.04). CONCLUSION: This review acknowledged the interdependent nature of sleep among cancer patients and caregivers. Our results could have significant implications in sleep management for healthcare professionals working with dyads impacted by cancer, particularly bed-sharing couples. Since limited RCTs examined the effectiveness of dyadic interventions on sleep promotion in cancer dyads, further research needs to provide more rigorous evidence in this population.