Giovanni Lombardi, Anna Castelnovo, Mauro Manconi, Salvatore Galati, Silvia Miano
This exploratory study characterises the scalp topography and spectral properties of CAP A subtypes in typically developing children using HD-EEG. Slow-frequency CAP activity declined across the night, consistent with homeostatic processes, whereas faster components showed a frontal predominance and a late-night increase. These findings highlight developmental differences in CAP organization and provide preliminary reference data for paediatric sleep research, which require confirmation in larger, multicentre cohorts.
BACKGROUND: The cyclic alternating pattern (CAP) is a key marker of NREM sleep microstructure, reflecting the balance between sleep-protective (A1) and arousal-promoting (A2/A3) processes. However, normative spectral and topographic data for CAP subtypes during development are limited, and high-density EEG (HD-EEG) mapping in children is lacking. This study aimed to characterize the scalp topography and spectral properties of CAP A subtypes in typically developing children and to assess their overnight dynamics.
METHODS: Nineteen typically developing children (mean age 10.2 years, range 8-13.7; 10 females) underwent overnight video-polysomnography with 256-channel HD-EEG. Power spectral density was estimated using Welch's method for CAP A1 (0.5-2.5 Hz), A2-low (0.5-2.5 Hz), A2-high (11-14 Hz), and A3 (11-14 Hz). Topographic distributions were computed across the night and compared between early and late NREM sleep using linear mixed-effects models with permutation-based TFCE correction.
RESULTS: A1 and A2-low activity showed maximal power over fronto-central and centro-parietal midline regions and was significantly higher during early compared to late night. In contrast, A2-high and A3 activity displayed a predominantly frontal distribution and increased during the late night. High-frequency components of A2 and A3 peaked within the 11-14 Hz range, differing from the alpha-band activity typically reported in adults.
CONCLUSIONS: This exploratory study characterises the scalp topography and spectral properties of CAP A subtypes in typically developing children using HD-EEG. Slow-frequency CAP activity declined across the night, consistent with homeostatic processes, whereas faster components showed a frontal predominance and a late-night increase. These findings highlight developmental differences in CAP organization and provide preliminary reference data for paediatric sleep research, which require confirmation in larger, multicentre cohorts.