Non-Rapid Eye Movement Sleep Instability in Children With Epilepsy: A Systematic Review and Meta-Analysis of Cyclic...

Sleep and epilepsy share a bidirectional relationship, with epilepsy disrupting sleep microstructure in ways that remain poorly understood in children. The cyclic alternating pattern (CAP) quantifies non-rapid eye movement sleep instability through cortical arousal fluctuations, but paediatric-specific evidence is scarce. We systematically searched four databases through December 2025 for studies reporting CAP parameters in children with epilepsy compared with healthy controls. Pooled mean differences were estimated using random-effects models, and risk of bias and certainty of evidence were assessed using standardised frameworks. Four study comparisons (87 children with epilepsy, 53 healthy controls) from five publications met the inclusion criteria. Total CAP rate did not differ significantly between groups (mean difference 3.79%; p = 0.636), with extreme heterogeneity reflecting syndrome-related variation. Among subtype indices, the A3 Index was lower in children with epilepsy (mean difference -1.87 events per hour, 95% confidence interval -3.09 to -0.65; p = 0.003) with low heterogeneity, though significance was lost when the largest study was excluded and under conservative sensitivity analyses. The A2 Index reduction was statistically significant but not robust in sensitivity analyses. No significant differences were observed for the A1 Index or subtype percentages. Available evidence suggests that CAP alterations in paediatric epilepsy are heterogeneous and syndrome-specific rather than uniform. The A3 Index reduction emerged as the most consistent finding, but should be regarded as preliminary given the limited evidence base. Larger, longitudinal, syndrome-specific studies are needed before CAP measures can be considered clinically relevant.