title: Development of the 24-h rest-activity pattern in human infants.
abstract: The development of the 24-h rest-activity pattern was investigated in human infants under naturalistic conditions as assessed by continuous actigraphy. Seven infants and their mothers were recorded for 4 (n=1), 6 (n=5) and 12 months (n=1) after birth. Periodogram analysis of rest-activity data was performed over consecutive 10-day intervals. A weak 24-h rest-activity pattern was already present in some infants during the newborn period. The magnitude of the 24-h component in individual periodograms increased across the first months following a saturating function. The time constants of fitted saturating exponential functions--reflecting the rate of development of the 24-h pattern--ranged from 49 to 110 days (n=6) indicating a large interindividual variability. Furthermore, intraindividual variation was observed; the magnitude of the 24-h rest-activity component showed fluctuations around the trend. Miniaturized actigraphs are ideal tools for long-term longitudinal monitoring of rest-activity behavior in infants.
authors.affiliation: Growth and Development Center, University Children's Hospital Zürich, Steinwiesstrasse 75, CH-8032 Zürich, Switzerland. Oskar.Jenni@kispi.unizh.ch
authors.forename: Oskar G
authors.initials: OG
authors.lastname: Jenni
authors.forename: Tom
authors.initials: T
authors.lastname: Deboer
authors.forename: Peter
authors.initials: P
authors.lastname: Achermann
mesh_terms: D000328:Adult; D002657:Child Development / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009035:Mothers; D009043:Motor Activity; D012146:Rest / Q000502:physiology*