Activity-based assessment of sleep-wake patterns during the 1st year of life

The aim of this study was to examine the validity of activity-based monitoring (actigraphy) for the assessment of sleep-wake patterns during the 1st year of life. Forty-one infants were directly observed for sleep-wake state determination by trained observers. Concomitant activity data obtained by actigraphs attached to the infants' ankles during the observation were matched on a minute-by-minute basis, and a scoring algorithm was developed for automatic identification of sleep-wake states. Overall, the automatic scoring algorithm for activity data reached 95.3% agreement rate with the observers' sleep-wake scoring. Distinction of quiet and active sleep reached agreement rates ranging from 54% to 87% at different ages. Significant night-to-night stability was found for several derived sleep-wake measures, and high variability was noted for other measures. It is concluded that actigraphy provides valid sleep-wake measures during the 1st year of life.