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Individual differences, daily fluctuations, and developmental changes in amounts of infant waking, fussing, crying,

I St James-Roberts1, I Plewis

  • 1London University Institute of Education.

Child Development
|October 1, 1996
PubMed

Insights

Infant behavior, including sleeping, fussing, and crying, shows significant day-to-day instability. While development drives changes in waking and feeding, individual differences play a role in sleep and fussing patterns in infants.

Area of Science:

  • Developmental Psychology
  • Infant Behavior Studies
  • Behavioral Pediatrics

Background:

  • Infancy is characterized by rapid developmental changes and behavioral variability.
  • Understanding the sources of variance in infant behaviors is crucial for developmental research and clinical practice.
  • Previous studies have not fully disentangled developmental changes, individual differences, and day-to-day fluctuations in infant behaviors.

Purpose of the Study:

  • To quantify the contributions of developmental changes, individual differences, and day-to-day fluctuations to infant sleeping, awake-content, feeding, fussing, and crying.
  • To examine the stability of these behaviors across the first year of life.
  • To compare the patterns of variance for different infant behaviors.

Main Methods:

  • Multilevel analysis was used to examine infant behaviors at 2, 6, 12, and 40 weeks of age.
  • The study analyzed the variance attributable to individual differences, age-related changes (development), and day-to-day fluctuations within infants.
  • Key behaviors studied included sleeping, awake-content, feeding, fussing, and crying.

Main Results:

  • Day-to-day fluctuations accounted for the largest proportion of variance in sleeping, fussing, and crying (44-53%).
  • Developmental changes primarily explained waking and feeding, with no significant individual differences found.
  • Individual differences and development each contributed about 25% to the variance in sleeping, showing moderate stability from 6 weeks to 9 months.

Conclusions:

  • Infant behaviors exhibit significant instability, particularly in sleeping, fussing, and crying.
  • Developmental trajectories are prominent in waking and feeding, while sleep and fussing show both developmental and individual difference components.
  • Fussing demonstrates greater stability than crying, with early fussiness predicting later behavior, highlighting the importance of considering individual behavioral patterns.

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