• actigraphy;
  • concordance;
  • polysomnography;
  • school-age children


The aims of this study were to evaluate sensitivity, specificity and accuracy with an epoch-by-epoch comparison of polysomnography (PSG) and actigraphy with activity counts scored at low, medium and high thresholds, and to compare PSG-derived total sleep time (TST), sleep efficiency (SE) and wake after sleep onset (WASO) to the same variables derived from actigraphy at low, medium and high thresholds in 9- to 11-year-old children with juvenile idiopathic arthritis (JIA), asthma and healthy control children. One night of PSG and actigraphy were recorded. Pairwise group comparisons for sensitivity showed significant differences at the low [Tukey’s honest significant difference (HSD) < 0.002], medium (< 0.001) and high thresholds (< 0.001) between JIA and asthma groups, and at the high threshold between JIA and controls (< 0.009). Significant differences were found for specificity at the low (< 0.001), medium (< 0.001) and high thresholds (< 0.001) between JIA and asthma groups, and between JIA and controls (low, < 0.002: medium, < 0.002: high, < 0.008 threshold). PSG TST, WASO and SE were not significantly different among the groups, but significant group differences were found for actigraphy TST, WASO and SE at all three thresholds. Actigraphy showed the least overestimation or underestimation of sleep or wakefulness at the medium threshold for TST and WASO for all three groups. Compared to PSG, actigraphy was most accurate in the identification of sleep from wakefulness in 9- to 11-year-old healthy children, and less accurate in children with JIA and asthma.