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Published on: June 18, 2014
Do infants show a cortisol awakening response?
Melissa A Bright1, Douglas A Granger, Janet E Frick
1Department of Psychology, University of Georgia, Athens, GA 30602, USA. mbright@uga.edu
Insights
The cortisol awakening response (CAR) differs in infants compared to adults. Infant cortisol levels decreased after waking, unlike the typical adult CAR increase.
Area of Science:
- Endocrinology
- Developmental Psychology
- Neuroscience
Background:
- The cortisol awakening response (CAR) is a well-documented phenomenon in adults, reflecting hypothalamic-pituitary-adrenal axis activity upon waking.
- Previous research has primarily focused on the CAR in adult populations, with limited understanding in infants.
Purpose of the Study:
- To investigate the cortisol awakening response (CAR) in infants for the first time.
- To compare infant CAR patterns with established adult CAR responses.
Main Methods:
- Saliva samples were collected from 32 mothers and their infants (aged 7.8–17.4 months) upon waking and 30 minutes later.
- Cortisol levels were measured following morning waking and the infant's first nap.
Main Results:
- Infant cortisol levels showed a decline from waking to 30 minutes post-waking, contrasting with the adult CAR.
- No significant cortisol changes were observed following infant naps.
- Mother-infant cortisol levels were associated at both group and dyadic levels.
Conclusions:
- The cortisol awakening response (CAR) in infants appears distinct from that observed in adults.
- Infant sleep-wake cycles and associated hormonal responses warrant further investigation.
- Maternal and infant cortisol levels exhibit interconnectedness.
Abstract:
Upon awakening from sleep, combined processes of deactivation of the hippocampus and activation of suprachiasmatic nucleus result in a marked increase in cortisol release from structures within the hypothalamic-pituitary-adrenal axis. This phenomenon, termed the cortisol awakening response (CAR), has been studied extensively in adults. In the current study, we examine this phenomenon for the first time in infancy. Saliva samples were collected by 32 mothers from themselves and their infants (13 males; 7.8-17.4 months of age) at the infant's AM waking (and 30 min later), and upon waking from the infant's first nap (and 30 min later). In contrast to what has been observed with the CAR in adults, cortisol levels declined from AM waking to 30 min post-waking. Moreover, cortisol levels did not significantly rise or fall following naps. Consistent with prior research, both group-level and dyadic-level analyses showed that cortisol levels for mother-infant dyads were associated.
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