Cortisol levels in last trimester may predict infant sleep onset at 7 months

Key takeaways:

• Hair cortisol collected from 70 newborns, with sleep patterns reported by parents at 7 months.
• Study found that higher cortisol level predicted longer sleep onset latency.

INDIANAPOLIS — Newborns with higher levels of hair cortisol, a measure of fetal cortisol in the last trimester of pregnancy, were more likely to have delayed sleep onset at age 7 months, according to preliminary research.

“There may be prenatal influences on sleep health early in life, pointing to the need to better understand what factors may set the stage for better sleep health in infancy and beyond,” Tessa Benefield, BS, lead study co-author and research assistant for the Care Project at the University of Denver, said in a related release regarding data to be presented at the SLEEP 2023 meeting.

As cortisol may affect sleep regulation in the early postnatal period, Benefield and colleagues sought to examine associations between cortisol in the hair of newborns and their sleep health.

Researchers collected cortisol from the hair of 70 newborns (57.1% girls) participating in the Care Project, a longitudinal study in Denver, within a few days of birth.

Using information gathered from parents’ assessments of infant sleep health at 7 months via the Brief Infant Sleep Questionnaire, which includes measures of nighttime sleep duration and wakefulness, number of awakenings and sleep onset latency, researchers examined the link between newborn hair cortisol and sleep health, controlling for gestational age at birth and income-to-needs ratio.

According to results, a greater amount of hair cortisol was a reliable predictor of longer sleep onset latency at 7 months (r = 0.32). Conversely, researchers found no correlation between hair cortisol of newborns and nighttime sleep duration (r = –0.17), wake duration (r = 0.13) or awakenings (r = –0.13).

“Although increases in cortisol across pregnancy are normal and important for preparing the fetus for birth, our findings suggest that higher cortisol levels during late pregnancy could predict the infant having trouble falling asleep,” Melissa Nevarez-Brewster, BS, lead co-author and graduate student at the University of Denver, said in the release.

Reference:

• Newborns with higher hair cortisol levels take longer to fall asleep. https://www.sleepmeeting.org/newborns-higher-hair-cortisol-levels-take-longer-fall-asleep/. Published May 30, 2023. Accessed June 5, 2023.