Science Says: Will Sleep Training Harm My Baby?

will sleep training harm my baby
Alex Warrack

Alex Warrack

I remember being a new parent and feeling the exhaustion of sleepless nights. I was scouring the internet to find tips and support on how to create healthy sleep habits for my baby.

During my research, there was no shortage of scary headlines about sleep training, like:

  • “Dangers of Crying it out” (Psychology Today; Narvaez, 2011)
  • “Cry It Out: The Potential Dangers of Leaving Your Baby to Cry” (The Analytical Armadillo)
  • “Science Says: Excessive Crying Could be Harmful” (Sears, 2013)

If we get caught solely on the headline, we may form our opinion on sleep training based on these scary headlines. (no judgment – sleep deprivation is gnarly!)

You may have read these articles and thought “I will never sleep train!” Yet here you are reading this article and likely sleep-deprived, please note:

The articles above do not provide any scientific, evidence-based research to support their claims. In most cases, the articles had a preconceived notion and attempted to find research to support their claims. Many had to skew the research findings to suit their purpose.

So, let’s move away from the scary headlines. Instead, let’s focus on what science says on “will sleep training harm my baby?”

For this post, we chose three studies (out of many to choose from). We want to showcase the scientific, evidence-based research on the safety of sleep training.

These studies specifically looked at:

  • the cry-it-out method (aka CIO and extinction)
  • controlled crying method (aka Ferber or timed checks)
  • bedtime fading method (aka chair method)

Debunking Claims That Sleep Training Will Harm Your Baby

Study #1

Behavioral Interventions for Infant Sleep Problems: A Randomized Controlled Trial

In this study, researchers conducted a randomized controlled trial of 43 infants (aged 6-16 months). The purpose was to evaluate the effects of behavioral interventions (sleep training) on the infants. The study looked at:

  • wakefulness/sleep of infants
  • stress in parents and infants
  • latent child emotional/behavioral problems
  • parent/child attachment

This study randomly assigned the forty-three families to either use graduated extinction, bedtime fading, and the third group, a control group that had just sleep education.

The primary objective of the study was to assess infant’s sleep latency (how long it took for baby to fall asleep) and the number of night wakings and their duration.

The secondary objective was outcomes for infants’ cortisol (stress level), parent’s stress and mood, child-parent attachment, and child behavior. For each group, the family received training or information on how to properly execute the sleep training procedure.

Study Results

Sleep Latency

There was a decrease in the duration it took for the children to fall asleep in all three groups. Meaning children were learning to self-settle.

Night Wakings:

A large reduction in the number and duration of night wakings was seen when comparing the control group to sleep training groups.

Stress, Behavior and Attachment:

Extinction-based methods did not show any effect on any of these factors. After 12 months of age, the children that were from the graduated extinction group didn’t show any internal or external behaviors of concern compared to the other groups.

Bottom Line:

This study found that there were no detrimental effects on emotional or behavior problems, or insecure parent-child attachment by twelve months of age.

Study #2

Five-Year Follow-up of Harms and Benefits of Behavioral Infant Sleep Intervention: Randomized Trial

This study aimed to determine the long-term harm and/or benefits of an infant behavioral sleep program at age 6 years. It looked at factors relating to the:

  • child
  • child-parent relationship
  • maternal outcomes

The original study started when babies were seven months old and the parents reported infant sleep problems.

The first group, the control group, received normal care. The second group, the intervention group, received between 1-3 individual nurse consultations.

The infants were aged 8 to 10 months at the time. During these consultations, behavioral infant sleep interventions were discussed.

They compared the control group and the intervention group to determine the impact to:  

  • child’s emotional and conductive behavior
  • sleep problems
  • psychosocial health related to the quality of life
  • elevated cortisol as a marker of stress for child and parent relationship
  • child-parent attachment
  • parent depression, anxiety, and stress scores 


There was little to no difference between the intervention group and the control group scoring. For example, both groups scored the same for the emotion score and behavior score.

Furthermore, the intervention group and control group also had the same score for child-parent closeness.

Bottom Line:

The study concluded that there are no long-term harms of sleep training on infants up to the age of six years old.

“Parents can confidently use these techniques to reduce the short-to-medium-term burden of infant sleep problems and maternal depression.”

Lastly, the article concludes it is important for parents to have early education on infant sleep habits to prevent future sleep problems.

Study #3

Behavioral Treatment of Bedtime Problems and Night Wakings in Infants and Young Children

The American Academy of Sleep Medicine conducted a review of 52 studies. The review looked at evidence that has been collected for the success of behavioral changes. Specifically, they were looking at bedtime problems and night wakings in infants and children.

The goal was to provide a review of the impact had on the child and parent. They also looked at if the healthy sleep habits stuck after the initial training period.


From a sleep perspective, “94% report that behavioral interventions produced clinically significant improvements in bedtime problems and/ or night wakings”. (p. 1272)

Within that finding, 82% were able to maintain these skills for three to six months post-intervention.

Aside from the sleep benefits, they also found that there weren’t any adverse effects to factors outside of sleep. Most notably:

  • Infants who participated in sleep training, after treatment, were found to be:
    • more secure
    • more predictable
    • less irritable
    • less crying and fussing
  • There was no effect on maintaining breastfeeding, or on the infant’s daily fluid intake
  • Parents of older children reported improvements in their child’s daytime behavior after participation
  • Improvement in the well-being of parents beyond their child sleep better, including:
    • Rapid improvement in mental health
    • Reporting fewer symptoms of depression
    • Increased sense of being an effective parent
    • Enhanced marital satisfaction
    • Reduced parenting stress

Bottom line:

These articles support the argument that using the most common sleep training methods does not cause long-term negative emotional or attachment challenges with little ones and their parents.

In short, we’ve reviewed the studies and answered the important question “Will sleep training harm my baby?” Now, I want you to know…

  1. If you want to do sleep training with your little one, all methods of sleep training are completely safe.
  2. Choosing to sleep train may or may not be the right choice for you. Above all, it is your choice to make an informed decision. Not a decision that is based on fear and untruths.
  3. If you need help picking a sleep training method or need support, we are here to help, in a supportive, non-judgmental way! Book a discovery call to learn more about working with us.

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