title: Differential effects of breast- and formula-feeding on preterm infants' sleep-wake patterns.
abstract: OBJECTIVE
  To compare sleep-wake patterns of breastfed and formula-fed preterm infants.
  
  
  METHODS
  Data were taken from an exploratory study of infant biorhythm maturation. Parents completed a 24-hour diary of infant Sleep, Awake, and Cry states and feedings, recorded at 30-minute intervals. Infant health data were collected from medical records and parents' reports.
  
  
  METHODS
  Infants were studied in the home after discharge from a neonatal intensive-care unit.
  
  
  METHODS
  The convenience sample included 12 breastfed and 25 formula-fed preterm infants (gestational age, 26-33 weeks; corrected postnatal age, 4-6 weeks). Groups were comparable in terms of gestational age, postnatal age, Apgar scores, maternal age, and home environment.
  
  
  METHODS
  The 24-hour recording period was divided into day (0600-1800) and night (1800-0600). Study variables were Day, Night, and 24-hour Sleep, Awake, and Cry.
  
  
  RESULTS
  Breastfed preterm infants exhibited more Day Cry and 24-hour Cry than did formula-fed infants. Infants demonstrated a diurnal pattern in Cry, Awake, and Sleep. Breastfed preterm infants cried approximately 1 hour per day more than formula-fed infants.
  
  
  CONCLUSIONS
  Preterm breastfed infants experienced more cry than did formula-fed infants. The relationship between feeding method and sleep-wake pattern has implications for supporting lactation as well as for research design.
authors.affiliation: Department of Family and Child Nursing, University of Washington, Seattle 98195-7262, USA. kthomas@u.washington.edu
authors.forename: K A
authors.initials: KA
authors.lastname: Thomas
mesh_terms: D000704:Analysis of Variance; D001903:Bottle Feeding; D001942:Breast Feeding; D002940:Circadian Rhythm / Q000502:physiology*; D003448:Crying; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D008297:Male; D008991:Monitoring, Physiologic; D012016:Reference Values; D012044:Regression Analysis; D012890:Sleep / Q000502:physiology*