Cortisol levels decreased in infants from the time of
waking to 30 minutes after waking, according to study results.
Researchers at the University of Georgia and Johns
Hopkins School of Nursing said the hippocampus is deactivated and the
suprachiasmatic nucleus is activated upon waking in adults. When these two
things occur, an increase in cortisol release from structures within the
hypothalamic-pituitary-adrenal axis also occurs and is known as the cortisol
awakening response. The current study investigated this response in infants.
Thirty-two mothers collected saliva samples from
themselves and their infants (aged 7.8-17.4 months) at four time points: when
the infants awoke in the morning; 30 minutes after morning waking; when the
infants awoke from a first nap; and 30 minutes after that.
A decline in cortisol awakening response was observed in
infants between morning waking and 30 minutes after waking. Cortisol levels at
waking were 0.35 mcg/dL (standard deviation [SD]=0.20) and 0.29 mcg/dL
(SD=0.16) 30 minutes after waking (P=.046).
No significant increase or decrease in cortisol levels
was observed after naps.
No significant variation in cortisol levels was observed
in mothers after infants transitioned from sleep to waking in the morning or
Prior research has suggested links between cortisol
levels for mother–infant pairs. Results of the current study demonstrate a