Use of the Sonomat for Evaluating Nocturnal Body Movements in Children.

Abstract

Movements during sleep are routinely observed but not consistently quantified in paediatric sleep assessment. This thesis evaluates the Sonomat (MAT) alongside polysomnography (PSG) for measuring sleep-related body movements. In a retrospective cohort of children with concurrent Sonomat and PSG studies, movements were scored using event-duration thresholds (≥1s, ≥3s, ≥5s, ≥7s). Movement index (MI, events/h) and movement duration (MD, % of time) were determined. Analyses examined inter-system agreement, automated scoring, and whether movement burden differed by obstructive sleep apnoea (OSA) status, including within children with McGill oximetry scores of 1.

The Sonomat consistently measured higher MI and MD than PSG, detecting more brief movements. This difference lost statistical significance for MI when restricted to movements ≥7s. MD remained statistically significant, though the clinical relevance of a 0.9% difference (~4.5 min of median total sleep period) is unclear. At the 3s threshold, inter-system agreement reached 88%. MD emerged as the preferred burden metric, being less sensitive to event-splitting or merging than MI. Automated MAT scoring showed asymmetry, with MD most closely approximating manual scoring.

Movement burden, especially MD, strongly correlated with wakefulness. No discrimination by OSA status was found in overall or sleep-restricted analyses. Small cohort size and retrospective design limited power for sub-analyses, including within the McGill score 1 group. Snoring and stertor are captured by Sonomat but not by the mixed obstructive apnoea-hypopnoea index (MOAHI).

In summary, the Sonomat is viable for measuring sleep-related body movements, detecting more brief events than PSG but converging for events ≥7s. MD provides a more robust burden measure than MI. Movement metrics tracked wakefulness but did not differentiate OSA status by MOAHI. Future work should examine larger cohorts and broader sleep-disordered breathing criteria.