Sleep and cry behavior in excessively crying infants: A systems perspective

Date of Completion

January 2000


Psychology, Psychobiology|Psychology, Behavioral|Psychology, Developmental




The behavior of infants who cry excessively was studied within the context of the mother-infant system. In the first study, the incidence of parent-defined infant irritability was 19% in a large sample (N = 1479) of mother-infant dyads over three consecutive years. Parents who reported excessive infant irritability were also more likely to report infant medical problems and sleep difficulties. ^ The connection between infant irritability and sleep problems was further assessed by measuring sleep state organization in a group of irritable infants and in age-matched comparison infants. Sleep state organization was found to differ significantly between the irritable infants and age-matched comparison infants at both 5 weeks (w5) and 6 months of age (m6). At w5, irritable infants' sleep patterns showed sleep fragmentation. At m6, the irritable infants continued to show disrupted state organization, specifically showing less mature state patterns than the comparison group. ^ The irritable infants' sleep patterns were further studied by dividing the sample into low, moderate, and high criers based on how much they cried at w5. The highest crying infants were found to have significant sleep fragmentation compared to the lowest crying infants, but only at 9 weeks of age. ^ The mother-infant system of the irritable infants was assessed by looking at infant crying, maternal depression scores, and mother-infant interaction. Mothers with high depression scores (Depressed Mood group, DM) were compared to mothers with low depression scores (non-DM) on measures of mother-infant interaction at m6. ^ W5 DM mothers did not differ from w5 non-DM mothers on observed m6 mother-infant interactions. However, m6 DM mothers had significantly less direct attention, interactional attention, and affection toward their infants than m6 NDM mothers. They also spent more time out of the room from their infants and held them less frequently. The amount of infant crying was not directly related to maternal depressed mood or to the quality of mother-infant interaction. ^ In conclusion, infant crying is a behavioral manifestation of endogenous physiological activity. Irritable infants have altered neurobehavioral development, which depends upon transactions between the endogenous system, the infants behavior, and the care-taking environment. ^