It can be difficult to listen to a baby wail in his or her crib at nighttime, but a new study finds that leaving a little one to "cry it out" does not raise the baby's stress level, and may actually lead him or her to get more shut-eye over time.
The findings may give sleep-deprived parents more insight into which parenting strategies could work best for their babies, the researchers said.
However, they cautioned that the study was small and included mostly higher-income, well-educated families. Therefore, more research is needed to see whether the findings apply to other groups, they said. [11 Facts Every Parent Should Know About Their Baby's Brain]
In the study, the researchers randomly placed 43 infants, ages 6 to 16 months old, who had trouble falling and staying asleep at night, into one of three groups. In one group, parents tried "graduated extinction," in which they didn't respond to the babies' cries immediately but would eventually comfort the child briefly without picking him or her up or turning on the lights. If the baby cried again, the parents would wait a little longer before they went to comfort the baby, and so on until the baby fell asleep.
In the second group, the parents tried "bedtime fading," which meant that if the babies had trouble falling asleep the night before, parents would put them to bed later the next night. But the parents still comforted the child as they normally would at night. In the third group, which acted as the control group, parents simply received educational information about sleep strategies for babies, and no specific instructions.
The first two methods are controversial, largely because of the belief that letting a baby cry can be stressful for both infants and parents, and may increase their levels of the stress hormone cortisol, the researchers said. To measure the stress levels of the babies in the study, the researchers analyzed the babies' cortisol levels from cotton swabs of their saliva that the parents collected in the mornings and afternoons.
The study found that, within three months, the 14 babies in the graduated-extinction group (the ones who were left to cry) and the 15 babies in the bedtime-fading group (the ones who were put to bed later the following night) started falling asleep faster at night compared with the 14 babies in the control group. Moreover, those in the graduated-extinction group woke up fewer times during the night than the babies in the control group did at the three-month mark, the researchers found.
The results also showed that the afternoon cortisol levels in the babies in the two sleeping intervention groups dropped more over time than those of the babies in the control group, indicating less stress, the researchers said.
It's possible that these methods work because the babies learn to soothe themselves, stop crying and go to sleep, the researchers said.One year after the intervention started, the mothers assessed their children, looking for any emotional or behavioral problems, and underwent a test evaluating parent-child attachment. There were no differences among the groups in terms of the children's behavioral and emotional temperaments, the researchers said. [10 Scientific Tips for Raising Happy Kids]
The study also found that the mothers' moods improved over time in all three groups, but that this improvement was especially strong for those in the bedtime-fading group, the researchers found.
The new study provides pediatricians and parents with solid evidence about which sleep methods work best for babies, said Dr. David Gozal, an expert in pediatric sleep and a professor of pediatrics at the University of Chicago who was not involved with the study.
"For young infants, it has been our usual recommendation to teach the baby to self-soothe through a process of graduated extinction, very similar to the one implemented in this study," Gozal told Live Science. However, parents who want results need to persevere, he said.
"Perseverance and determination to succeed are key, since different infants will require different periods of time before they 'get with the program,'" he said. "If, however, after a reasonable period of truly trying [a method] things are not improved, switching to another method is always an option."
The study was published in the May issue of the journal Pediatrics.
Original article on Live Science.
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Laura is the archaeology and Life's Little Mysteries editor at Live Science. She also reports on general science, including paleontology. Her work has appeared in The New York Times, Scholastic, Popular Science and Spectrum, a site on autism research. She has won multiple awards from the Society of Professional Journalists and the Washington Newspaper Publishers Association for her reporting at a weekly newspaper near Seattle. Laura holds a bachelor's degree in English literature and psychology from Washington University in St. Louis and a master's degree in science writing from NYU.