Associations between Infants' Crying, Sleep and Cortisol Secretion and Mother's Sleep and Well-Being

Background: Infants' continuous crying is a challenge both for the child and the principal caregiver. However, the links between infants' sleep, crying and cortisol secretion and mothers' well-being and sleep have been scarcely investigated. The aim of the present study was therefore to examine the link between cortisol secretion, crying and sleep of infants characterized by infantile colic (IC) and mothers' psychological well-being and own sleep. Methods: Mothers of 24 infants characterized by IC (mean age = 8 weeks, SD = 1.5 weeks) completed a series of questionnaires regarding the infant's crying and sleeping patterns. Infants' sleep was objectively assessed with actigraphs. Cortisol secretion was measured by means of saliva samples in the mornings after waking. After 4 weeks, infants were assessed once again. Mothers completed questionnaires assessing their psychological well-being (depressive symptoms, family strain) and sleep. Results: Mothers' psychological well-being and sleep was greatly predicted by infants' morning saliva cortisol levels, sleep disruptions and crying intensity, whereas infants' crying duration and volume had low predictive value. Conclusions: Mothers with infants characterized by IC are at increased risk for reporting impaired sleep, developing depressive symptoms and reporting higher family strain. Most importantly, this risk seems to be greater if their infants' sleep is fragmented.