Will Sleep Training Harm My Baby?

Many parents find themselves in an unsustainable sleep situation due to lack of sleep from nighttime parenting. Unfortunately, there is no cry-free solution that yields effective, quick results (if there was, someone would be very, very wealthy!). No parent likes to hear their baby cry. It feels counter-intuitive to willingly allow your baby to cry and many parents worry that the crying involved in many sleep training methods will harm their baby. With buzzing social media feeds, endless google searches, and conflicting research studies, it can be overwhelming and difficult to know how to best navigate sleep training while keeping your baby’s well-being and safety a top priority.

In short, there is no high-quality, peer-reviewed evidence that shows that sleep training* is harmful; in fact, the evidence shows there is no negative effect on infant attachment or cortisol levels; and there are very clear positive effects on maternal mental health and improved outcomes for infant and childhood development. This article will include a summary of the available, high-quality peer-reviewed evidence on sleep training.

Topics covered in this article:

  • What does the research tell us about the short-term and long-term effects of sleep training? 
  • Is it really okay to let your baby cry?
  • Will sleep training jeopardize your baby’s bond with you?
  • A mother and pediatric sleep consultant weighs in.

Is it really okay to let my baby cry?

Only you as the parent to your child can fully answer this question and reconcile the pros against the cons of sleep training.  

We know the benefits of sleep training: improved sleep for the entire family, improved maternal mental health(1), and improved infant and childhood development. 

But what about the risks? Because the research is so limited, one cannot say with 100% certainty that there are zero risks associated with sleep training but the quality evidence we have does not indicate any negative short-term or long-term negative effects from sleep training.

A research study from 2012 (that is commonly cited amongst critics of sleep training) concluded that the crying involved in sleep training causes babies to enter into a stressed state with increased cortisol levels (2). However, there were significant limitations of this study: (A) the study was conducted in an a hospital setting and (B) the parents were not allowed to attend to their baby during the sleep training process. As such, it cannot be concluded that when sleep training occurs in the comfort and familiarity of a baby’s home under the care and supervision of a loving parent that cortisol levels are increased as a result of sleep training. 

Will sleep training ruin my baby’s bond with me? 

Assuming you are a responsive, attentive, loving, and caring parent (which you most likely are if you’re reading this article!), then there is no evidence to suggest that the limited crying involved in the sleep training process will harm your relationship or bond with your baby. 

Today’s parents are often bombarded with judgment, guilt-trips, and shame-inducing social media posts condemning sleep training and purporting its effects to be detrimental to a baby’s well-being and in direct opposition to attachment parenting ideologies. However, these claims are unfounded in the research and, furthermore, confuse the attachment parenting movement with attachment theory(3), asserting that sleep training threatens a secure attachment. 

Secure attachment is a concept from attachment theory (“attachment parenting” is not based on a correct understanding of attachment theory). 

Let me explain: A secure attachment is one that is built out of a loving, responsive, and trusting relationship, which involves a healthy balance of dependence and independence. Helping a child learn how to do something they are not capable of doing on their own builds trust and security in being dependent. Helping a child do something they are capable of doing themselves with love and confidence in their abilities (rather than doing it for them!), builds their self-confidence and gives them permission to learn new skills and to be independent. 

This is what the sleep training process does- it teaches a baby how to self-soothe and be more independent, all under the framework of a loving, supportive, and trusting relationship, specifically, secure attachment. The two do not have to be mutually exclusive, despite what many “experts” may say! 

Again, those who assert that sleep training jeopardizes healthy attachment misunderstand what it means to be securely attached.  

One of the best long-term studies(4) we have on sleep training did not find any long-term difference between the children who had been sleep trained as babies and those who hadn’t: “[It was] concluded that there were no harmful effects on children’s behavior, sleep, or the parent-child relationship” (4).  

Want my take on the crying involved in sleep training? 

I see the crying during sleep training as your baby’s way of expressing their displeasure at the new way of doing things (i.e., being asked to fall asleep on their own!). Your baby is protesting the change while they are practicing and learning a new skill: how to fall asleep independently. Most babies are angry and frustrated during the sleep training process not lonely, sad, or scared, as many parents are inclined to project (naturally, they’d much prefer to have you do the work of putting them to sleep!). Especially with regular check-ins throughout the sleep training process- that serve to reassure your baby, to show them that they are safe, you are there, you are condoning the development of this new skill- personally, as a mother of three children and as a pediatric sleep consultant, I am not concerned with the limited crying associated with sleep training. 

Your baby is loved, fed, and cared for- and now you are setting an important boundary so your baby can learn a new and very important skill. As parents, it’s our responsibility to set boundaries for our children so that they stay safe, learn important life skills, and ultimately flourish. I’m constantly setting boundaries for my three children- ages 12, 10, and 2 (around school work, screen time, sugar-intake, Nintendo, and using the potty to name a few!). 

As children, it’s their prerogative to test our boundaries but if we can stay resolute, our children will feel safe and they will learn and grow more easily. For many, sleep training is the first boundary we really set for our child (for example, I will no longer hold you to sleep); it’s hard to set boundaries and to endure our children’s protests but it’s often paramount to good parenting and getting the results we all desire: healthy, thriving children! 

I allowed all of my three children (when they were 4-6 months) to cry unattended for limited periods of time during the sleep training process. While it was hard, it worked and we all benefited from it. I would never recommend any parenting approach that I wouldn’t use myself for my own children.


The bottom line: 

Sleep training is currently a controversial topic, as are most big parenting topics. It’s particularly tricky as the scientific data is limited (there are only 12-15 high-quality studies available- many of which I’ve cited in this article and some of which rely heavily upon parental reporting which can be highly biased). As with any decision that involves your child, only you as the parent can make the best decision for them, ultimately trusting yourself to know what is best. 

Our babies are not robots; there is not a “one-size-fits-all” approach that will work for everyone. As such, sleep training should be highly individualized (what may have worked for your best friend and her baby may not work for you and your baby!); the method that you choose should depend on your child’s temperament, your parenting style, and ultimately what you feel comfortable taking on. Want to discuss an individualized sleep solution for your family? I’m here to help!!

Want to learn more? Listen to my recent guest appearance on this podcast! 

*Note: “Sleep training” in this article refers to methods that use “graduated extinction” (controlled crying for short intervals of time).


  1.  Hiscock, Harriet & Bayer, Jordana & Hampton, Anne & Ukoumunne, Obioha & Wake, Melissa. (2008). Long-term Mother and Child Mental Health Effects of a Population-Based Infant Sleep Intervention: Cluster-Randomized, Controlled Trial. Pediatrics. 122. e621-7. 10.1542/peds.2007-3783.
  2. Middlemiss W, Granger DA, Goldberg WA, Nathans L. Asynchrony of mother-infant hypothalamic-pituitary-adrenal axis activity following extinction of infant crying responses induced during the transition to sleep. Early Hum Dev. 2012 Apr;88(4):227-32. doi: 10.1016/j.earlhumdev.2011.08.010. Epub 2011 Sep 23. PMID: 21945361.
  3. Benoit D. Infant-parent attachment: Definition, types, antecedents, measurement and outcome. Paediatr Child Health. 2004 Oct;9(8):541-545. doi: 10.1093/pch/9.8.541. PMID: 19680481; PMCID: PMC2724160.
  4. Anna M.H. PriceMelissa WakeObioha C. UkoumunneHarriet Hiscock; Five-Year Follow-up of Harms and Benefits of Behavioral Infant Sleep Intervention: Randomized Trial. Pediatrics October 2012; 130 (4): 643–651. 10.1542/peds.2011-3467
  5. Bilgin A, Wolke D. Parental use of “cry it out” in infants: no adverse effects on attachment and 12 behavioural development at 18 months. J Child Psychol Psychiatry. 2020;61(11):1184-1193. doi:10.1111/jcpp.13223

About Author : Ellie Lindenmayer

Ellie Lindenmayer is the founder of Joyful Birthing & Beyond. She is a childbirth educator, HypnoBirthing Practitioner, birth doula, lactation counselor and sleep consultant. She is a mother of three and passionate about all things birth & baby!