Delta sleep instability in children with chronic arthritis

The objective of the present study was to evaluate the expression of a cyclic alternating pattern (CAP) in slow wave sleep (SWS) in children with the well-defined chronic syndrome juvenile idiopathic arthritis (JIA). Twelve patients (9-17 years of age), 7 girls, with JIA were compared to matched controls by age, pubertal stage and gender. After one night of habituation in the sleep laboratory, sleep measurements were obtained by standard polysomnography with conventional sleep scoring and additional CAP analyses. The sleep parameters of the JIA and control groups were similar for sleep efficiency (91.1 +/- 6.7 vs 95.8 +/- 4.0), sleep stage in minutes: stage 1 (16.8 +/- 8.5 vs 17.8 +/- 4.0), stage 2 (251.9 +/- 41 vs 262.8 +/- 38.1), stage 3 (17.0 +/- 6.0 vs 15.1 +/- 5.7), stage 4 (61.0 +/- 21.7 vs 77.1 +/- 20.4), and rapid eye movement sleep (82.0 +/- 27.6 vs 99.0 +/- 23.9), respectively. JIA patients presented nocturnal disrupted sleep, with an increase in short awakenings, but CAP analyses showed that sleep disruption was present even during SWS, showing an increase in the overall CAP rate (P < 0.01). Overall CAP rate during non-rapid eye movement sleep was significantly higher in pediatric patients who were in chronic pain. This is the first study of CAP in pediatric patients with chronic arthritis showing that CAP analyses can be a powerful tool for the investigation of disturbance of SWS in children, based on sleep EEG visual analysis.