Psychologists clash over the safety and effects of the cry it out parenting strategy

A study published in the Journal of Child Psychology and Psychiatry found that occasionally letting babies cry does not harm their behavioral development or their bond with their mothers. The research suggests that parents who let their infants fuss for a little while are not causing long-term psychological damage. These results offer reassurance to parents navigating the exhausting challenges of infant sleep and crying.

For decades, parents and psychologists have debated how quickly a caregiver should respond to a crying baby. One school of thought, rooted in attachment theory, suggests that parents should soothe a crying baby immediately. Attachment theorists argue that prompt responses help the infant form a secure emotional bond with the caregiver.

A secure bond gives the child the confidence to explore the world, knowing their parent is a safe haven. Another perspective comes from behaviorism, a branch of psychology focused on how learning shapes actions. Behaviorists suggest that immediately comforting a crying baby might accidentally reward the crying, leading to more tears in the future.

They propose that giving babies a chance to cry it out can reduce crying overall. By stepping back, parents might give their children the space to learn how to soothe themselves. Psychologists Ayten Bilgin and Dieter Wolke set out to test these conflicting ideas.

Bilgin is a researcher at the University of Warwick in the United Kingdom, where Wolke is a professor. They wanted to see how different approaches to crying influence infant development over time in a modern context.

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“Only two previous studies nearly 50 or 20 years ago had investigated whether letting babies ‘cry it out’ affects babies’ development. Our study documents contemporary parenting in the UK and the different approaches to crying used,” Bilgin said.

The first of those older studies took place in 1972 and involved just 26 families. That early study suggested that ignoring cries led to more crying and an insecure attachment. Later attempts to replicate those results showed contradictory outcomes, leaving modern parents without clear guidance.

To gather more reliable data, Bilgin and Wolke followed 178 infants and their mothers from birth to 18 months of age. The researchers tracked a mix of full-term babies and those born early or with a low birth weight. Mothers reported how often they let their infants cry it out at birth, three months, six months, and 18 months.

The mothers answered whether they used this approach never, once, a few times, or often. They also recorded how long and how frequently their babies cried during the morning, afternoon, evening, and night. When the babies reached 18 months of age, the researchers assessed their behavioral development using multiple tools.

Independent observers watched the toddlers play to evaluate their attention spans, hyperactivity, and social skills. They rated the infants on their ability to persist at tasks and their general emotional tone. Parents also filled out questionnaires detailing any behavioral issues they noticed at home.

The researchers also measured the emotional bond between mother and child using a well-established psychological test called the strange situation procedure. During this laboratory test, researchers observe how a toddler reacts when a parent leaves a room and then returns. This brief separation reliably triggers the infant’s attachment behaviors.

This test helps classify the child’s attachment style. A secure attachment means the child feels safe exploring and is easily comforted by the parent upon their return. Insecure attachment means the child might avoid the parent or show high levels of anxiety and resistance.

The researchers discovered that leaving a baby to cry was rare right after birth. Most mothers responded to their newborns immediately. As the babies grew older, parents were more likely to let them cry a few times or often.

Letting an infant cry occasionally right after birth was associated with less frequent crying at three months of age. Letting infants cry a few times at birth and often at three months was linked to shorter crying durations when the children reached 18 months. The results regarding negative impacts on infant development were not statistically significant.

In fact, the study revealed no adverse impacts on infant-mother attachment at 18 months. Babies who were left to cry developed the same secure bonds as those who were comforted immediately. The researchers also found no negative effects on the toddlers’ behavioral development, such as increased aggression or hyperactivity.

Professor Wolke noted that parents naturally adjust their parenting as their children grow. “We have to give more credit to parents and babies. Most parents intuitively adapt over time and are attuned to their baby’s needs, wait a bit before intervening when crying and allow their babies the opportunity to learn to self-regulate. Most babies develop well despite their parents intervening immediately or not to crying.”

The study does have a few limitations that readers should keep in mind. The researchers relied on maternal self-reports to measure how often babies cried and how often parents let them cry it out. While maternal reports are generally reliable, independent observations over the entire 18 months would have provided more objective data.

The research was also observational, meaning it could not prove a direct cause and effect between parenting choices and infant behavior. The study did not measure crying frequency at the six-month mark, leaving a slight gap in the timeline. Finally, the questionnaire did not ask parents to distinguish between daytime and nighttime crying.

Following the publication, researchers Abi M. B. Davis and Robin S. S. Kramer published a commentary questioning the study’s conclusions. They argued that ignoring infant crying goes against human evolutionary drives. Children cannot communicate their pain or hunger with words, so crying is their primary survival tool.

Davis and Kramer suggested that failing to respond might increase an infant’s stress levels. They pointed to previous theories suggesting that elevated stress hormones, like cortisol, can negatively impact brain development. They expressed concern that parents might read the study and begin ignoring their infants’ genuine needs.

The commentary authors also raised concerns about the statistical power of the research. They argued that the sample size of 178 infants was too small to confidently detect minor negative effects on attachment types. They worried that grouping different types of insecure attachment together might hide subtle problems.

Additionally, Davis and Kramer pointed out that the study did not provide parents with a strict definition of what it means to let a baby cry it out. Without a set definition, mothers might have interpreted the question differently. Some might have thought it meant leaving a child alone in a crib, while others might have pictured sitting in the same room while the child fussed.

Bilgin and Wolke later published a detailed response to this critique. They clarified that their study did not recommend entirely ignoring a crying baby. Their findings simply showed that modern parents who occasionally delay their responses do not harm their children.

The original authors noted that an experiment randomly assigning parents to ignore their babies would be impossible and unethical. Parents hold strong personal views on raising children and would not agree to be randomly assigned to a parenting style. Because of this, observational studies remain the best available option for understanding these dynamics.

Addressing the statistical concerns, Bilgin and Wolke explained that their sample size was large enough to detect meaningful differences in attachment. They highlighted that three modern studies tracking 365 infants have all found no link between delayed responding and insecure attachment. The only study to find a negative link was the 1972 project involving just 26 families.

Bilgin and Wolke also challenged the idea that crying it out causes dangerous stress. They cited an independent study showing that a sleep training program did not raise infant stress hormone levels. In reality, the maternal stress hormones decreased when mothers stopped rushing to intervene.

The researchers emphasized that maternal sensitivity during play and daily interactions is what truly builds a secure attachment. They found no differences in observed maternal sensitivity between mothers who let their babies cry and those who did not. A delayed response at bedtime does not equate to insensitive parenting.

Moving forward, researchers hope to explore how different types of crying might require different responses. Future studies could separate daytime fussing from nighttime waking to see if the time of day changes the impact of delayed responding. Tracking specific parental actions, such as whether a parent stays in the room while the baby cries, could also provide clearer insights.

Larger sample sizes will help scientists detect even smaller shifts in infant behavioral patterns. By combining data from multiple studies, psychologists can build a more comprehensive picture of how babies learn to manage their emotions. Ultimately, observing how parents naturally adapt to their infants over time will continue to inform our understanding of child development.

The study, “Parental use of ‘cry it out’ in infants: no adverse effects on attachment and behavioural development at 18 months,” was authored by Ayten Bilgin and Dieter Wolke.