title: Mother-infant circadian rhythm: development of individual patterns and dyadic synchrony.
abstract: BACKGROUND
  Mutual circadian rhythm is an early and essential component in the development of maternal-infant physiological synchrony.
  
  
  OBJECTIVE
  The aim of this to examine the longitudinal pattern of maternal-infant circadian rhythm and rhythm synchrony as measured by rhythm parameters.
  
  
  METHODS
  In-home dyadic actigraphy monitoring at infant age 4, 8, and 12 weeks.
  
  
  METHODS
  Forty-three healthy mother-infant pairs.
  
  
  METHODS
  Circadian parameters derived from cosinor and non-parametric analysis including mesor, magnitude, acrophase, L5 and M10 midpoints (midpoint of lowest 5 and highest 10h of activity), amplitude, interdaily stability (IS), and intradaily variability (IV).
  
  
  RESULTS
  Mothers experienced early disruption of circadian rhythm, with re-establishment of rhythm over time. Significant time effects were noted in increasing maternal magnitude, amplitude, and IS and decreasing IV (p<.001). Infants demonstrated a developmental trajectory of circadian pattern with significant time effects for increasing mesor, magnitude, amplitude, L5, IS, and IV (p<.001). By 12 weeks, infant phase advancement was evidenced by mean acrophase and M10 midpoint occurring 60 and 43 min (respectively) earlier than at 4 weeks. While maternal acrophase remained consistent over time, infants became increasingly phase advanced relative to mother and mean infant acrophase at 12 weeks occurred 60 min before mother. Mother-infant synchrony was evidenced in increasing correspondence of acrophase at 12 weeks (r=0.704), L5 (r=0.453) and M10 (r=0.479) midpoints.
  
  
  CONCLUSIONS
  Development of mother-infant synchrony reflects shared elements of circadian rhythm.
authors.affiliation: Department of Family and Child Nursing, University of Washington, Seattle, WA 98195-7262, United States. Electronic address: kthomas@uw.edu.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Thomas
authors.affiliation: Department of Biobehavioral Nursing and Health Systems, University of Washington, Seattle, WA 98195-7266, United States.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Burr
authors.affiliation: Barnard Center for Infant Mental Health & Development, Department of Family and Child Nursing, University of Washington, Seattle, WA 98195-7262, United States.
authors.forename: Susan
authors.initials: S
authors.lastname: Spieker
authors.affiliation: Department of Family and Child Nursing, University of Washington, Seattle, WA 98195-7262, United States.
authors.forename: Jungeun
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Psychology, University of Washington, Seattle, WA 98195-1525, United States.
authors.forename: Jessica
authors.initials: J
authors.lastname: Chen
mesh_terms: D056044:Actigraphy; D000328:Adult; D002657:Child Development / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008425:Maternal Behavior; D009034:Mother-Child Relations; D009035:Mothers; D009043:Motor Activity
keywords: Circadian rhythm; Development; Maternal–infant; Synchrony