Will sleep training ruin my child’s attachment?

Have you been told that sleep training negatively affects attachment or your child’s emotional development? I’m here to tell you no, it doesn’t. Ensuring you and your baby are happily getting the right amount of sleep in a safe environment is not a bad thing and I wish society could stop shaming parents who choose to do it. There’s way too much misinformation out there and here’s the real deal.


Firstly, you don’t have to do Cry it Out. There are many different methods with various levels of parent involvement and support. You just need to find what works best for your family. Oh, and what you choose to do for your family’s wellness is completely up to you! It’s no one else’s business.

Here are the things I hear most commonly when everyone is all on track and sleeping well after sleep training:

  • “I feel more attuned with my child’s needs and feelings after sleep training. We have a consistent routine and she just knows what to do with each of our sleep cues. If something is off, it’s way easier to figure out the other things that could be wrong because we have sleep sorted out. I feel like we are on the same page now.”

  • “I actually feel like I know what my child needs now. I am confident when putting them down for naps and bedtime and not second guessing my decisions all the time.”

  • “My baby is a completely different baby now that she is well rested! I had no idea she was just cranky and overtired before.”

  • “I feel like I can think/breathe/live/love/show up again. The mom rage has lessened and the fog is lifting. I don’t know how I lived in sleep deprivation for so long. I’m a way better parent now.”


If you want help to make a change, I’m here. I won’t make you feel judged - I’ll meet you where you’re at and I want to help you find a solution to your struggles. Let’s end the cycle of shame for parents who need to reach out for help and make a change.


Being intentional with developing healthy attachment means you help your child explore this world with you right beside them. They will come to know and trust that they can rely on you when they really need you. Part of that is understanding guidance to learn important life skills (like how to sleep) and age-appropriate independence.

There is so much more to it! But the bottom line is you CAN have a healthy attachment and a well rested baby and family with sustainable sleep habits.


Attachment Basics

Secure attachment is built on a caregiver’s consistent love and support. It’s a pattern of interactions build over time where our kids learn and know what to expect from us as they observe and engage in countless social interactions over years. A temporary period of sleep training will not ruin your child’s secure attachment. In fact, being consistent with your chosen method will likely strengthen it.


You are not there to remove obstacles or feelings, but you’re there to help them through it. By letting them feel necessary emotions during the growth process in a safe and nurturing environment with lots of support, our kids will build the resilience they need to thrive in this world. They will be kind and understanding because they will be able to trust and handle the outcomes of their actions in a health way. And if you consistently show up for them while also giving them opportunities to grow, you will nurture a beautiful, lifelong parent-child relationship.


*Please note, attachment theory or attachment science is different than an attachment parenting method. This article refers to the former - attachment theory or science.


Please take a look at the following multiple longitudinal, empirically based and peer-reviewed research studies in support of the benefits of sleep training.


Yes, it covers all sides! Remember that I’m not here to make babies (or parents) cry. We’re here to learn and this research supports healthy learning and growth in children. Part of the process is expressing emotions, and we need to understand that it’s okay to express emotions. For little ones, that means crying.

“Infant and parental factors interact to influence the development of self-soothing.”

Nighttime sleep-wake patterns and self-soothing from birth to one year of age: a longitudinal intervention study

“..infants who were consistently put into the crib awake were more likely to be self-soothers than infants who were consistently put into the crib asleep. Infants who required parental assistance to fall asleep at the beginning of each night were more likely to require parental assistance upon awakening in the middle of the night.”

Night Waking, Sleep-Wake Organization, and Self-Soothing in the First Year of Life

Sleep training improves infant sleep problems, with about 1 in 4 to 1 in 10 benefiting compared with no sleep training, with no adverse effects reported after 5 years. Maternal mood scales also statistically significantly improved; patients with the lowest baseline depression scores benefited the most.”

Behavioral sleep techniques have no marked long-lasting effects (positive or negative).

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

This is one of the most consistent findings in infant sleep research. Babies who fall to sleep on their own at the beginning of the night tend to sleep better during the night, whereas more active soothing from a parent at bedtime is associated with more disrupted sleep during the night.

All babies wake several times during the night, but those that know how to go to sleep on their own are more likely to be able to comfortably resettle in the night without crying for help from a caregiver.

This has been shown in studies from around the world, including the United States, Canada, Thailand , the U.K., and in a cross-cultural survey of more than 29,000 babies from 17 different countries.

Note: Be aware that actigraphy itself isn’t a super reliable way to measure sleep! It’s something, but it’s not everything.

This article: sleep training improves infant sleep with no adverse effects.

This article provides links to several studies on sleep training. These studies show that it is effective and that removing parental presence at bedtime was the main predictor of children being able to sleep a 6 hour stretch. Claims of negative effects due to any crying during sleep training have not been replicated by studies - they haven’t been able to do it. The one study most often cited is based on long term abuse and neglect, not on a healthy child in a happy, responsive home being allowed to cry for a controlled amount of time while a parent responds during a short term period. There have been many studies validating short and long term negative effects of sleep deprivation for both baby and parents. Follow up studies on children at six years of age show no difference in emotional issues, sleep issues or attachment issues between children who were sleep trained or not sleep trained.

This study discusses how Danish babies tend to cry much less overall and have less incidence of colic, despite unusually high breastfeeding rates in the country, which is typically correlated with more crying. The conclusion as to why? According to this article which discusses the study’s conclusions in plain language, “Danish parents are regularly credited with having a healthier, more relaxed approach to parenting, preferring to give their children what the book The Danish Way of Parenting calls “proximal development” – or the space to grow and explore . They do not, we are told, hover like helicopters over the cribs of their infants, literally or metaphorically – instead opting to put their offspring to sleep in prams outside, where they believe the air is cleaner.” We can deduce that because Danish parents don’t necessarily scoop the baby up at every fuss and noise, they learn to settle themselves earlier and more easily than most babies.

“Sleep consolidation evolves rapidly in early childhood. Parental behaviors at bedtime and in response to a nocturnal awakening are highly associated with the child’s sleep consolidation. The effects are probably bidirectional and probably create a long-term problem. Early interventions could possibly break the cycle.”

Factors Associated With Fragmented Sleep at Night Across Early Childhood

The truth is that nature – a baby’s unique genetic make-up – accounts for somewhere between about a quarter and a half of the variation in infant nighttime sleep patterns.

One of the ways that we influence our babies’ sleep patterns is through our attitudes and beliefs about infant sleep. These were measured in this Israeli study that surveyed 85 women beginning in pregnancy and when their babies were 1, 6, and 12 months old. The study also evaluated the babies’ sleep, allowing the researchers to see correlations between parenting philosophies and infant sleep patterns.

All of these mothers were caring and responsive, but their beliefs about infant sleep fell along a spectrum. Beginning in pregnancy, some mothers tended to interpret a waking baby as a distressed baby who always needed help from a caregiver. These mothers ended up taking a more active role in soothing their babies to sleep, and their babies also ended up waking more during the night in infancy.

Other pregnant mothers in the study believed that babies were capable of sleeping and that they didn’t always need help from a parent to sleep. These mothers were more likely to end up letting their babies settle on their own, and their babies ended up waking less during the night . This follow-up study found that mothers’ sleep philosophies at 12 months also impacted how their children slept at four years of age. These studies show that if we believe that our babies can sleep without our help, then they’re more likely to do so.

In this fascinating study published in 2015, 101 London infants were video-recorded through one night at 5 weeks and 3 months of age. All of the infants woke during the night, but at both ages, about one quarter of the babies resettled during the night without the help of their parents. Most didn’t cry upon waking, and the rest fussed or cried for an average of about one minute before going back to sleep. The published study included a 3-minute video example of a 3-month-old baby resettling during the night. An earlier study found that about half of 3-month-olds resettled in the middle of the night without help from a parent.

Although not all of the babies in these studies were observed to resettle themselves, it shows that the possibility is there, and more babies might resettle if given a few minutes to try.

Another study showed that when parents gave their 3-month-olds a few minutes to try to go back to sleep on their own after a night waking, they were more likely to be sleeping through the night at 12 months of age.

Between the 5-week and 3-month measurements, the London study also found that there was a clear developmental progression in lengthening sleep periods. By 3 months of age, 68% of babies were sleeping (or self-settling) for at least a 5-hour stretch during the night, and this was just as likely with exclusively breastfed babies as with formula-fed babies. There was also a big increase in the number of infants that sucked on their fingers or hands during sleep (from 18% at 5 weeks to 62% at 3 months). These babies were finding that a little comfort was as close as their own hands.

What about cortisol? Here we go.

Here’s why the Middlemiss study about cortisol does not prove anything about

sleep training:

1) Cortisol levels in both mom & baby were already elevated on the first day of the study. Before the bedtime routine or any crying even began.

This could be because:

  • they were in a clinical setting

  • the babies were handled by unfamiliar people instead of their parents

  • Mom’s anxiety about the separation

  • Maybe the most important: cortisol is a primary hormone produced by the body in reference to circadian rhythms which means there are natural ebbs and flows to cortisol throughout the night (and if the child is already overtired-- it will peak at bedtime).

It’s impossible to responsibly conclude that the cortisol was present only because of any subsequent crying that occurred. The fact that the children already had elevated cortisol levels before any sleep training was initiated indicates that those levels were not created by the process of sleep training. It could also be safe to assume that they were not sleeping well to begin with and had the overtired/stressed affects already present.

2) The study did not show any significant increase in levels between pre- and post-bedtime. Levels were also not measured at any time during the night; they were only measured right before the babies were put down, and shortly after they fell asleep. There were no measurements taken throughout the night.

3) The levels were also only measured on the first and third days of the five-day program. That’s pretty weird! They just stopped measuring the data a little more than halfway through the study. To draw any reasonable conclusions, there should have at least been measurement on the very last day of the study; drawing conclusions based on partial data seems irresponsible from a research perspective.

4) A final, and very important, issue with this study is that there was no control group. There was no group of babies undergoing sleep training in their home environment; there was no group of babies NOT undergoing any sleep training. A control group is an essential part of any experiment or study; anyone’s findings are as good as useless if I have nothing to pair it against.

Here’s what we do know about cortisol:

Cortisol can be measured in saliva, so it can be sampled in a non-invasive manner without causing additional stress, even while a baby is sleeping. Without unusual levels of stress, cortisol has a natural circadian rhythm, being 300-400% higher in the early morning than at its lowest point around midnight. This pattern does not develop until infants are several months old, and it is what helps them to sleep at night and be awake during the day.

A surge in cortisol outside of this normal pattern can indicate that a baby is stressed. However, it is simplistic to assume that any rise in cortisol is dangerous, given its importance to daily function. Cortisol is not a problem unless it is elevated for extended periods of time as in the case of chronic stress.

Babies have a very reactive HPA axis at birth. A newborn baby will have a strong cortisol response to a heel stick, a bath, or a physical exam.

In one study, newborns were given a mock exam two days in a row. On the first day, the babies had increased cortisol and cried during the exam. However, when the exam was repeated on the second day, the babies did not show an increase in cortisol, though they still cried almost as much as they had on the first day. Somewhere in their brains, they recognized that this experience had happened before. This study illustrates a positive stress response. The babies were initially stressed by the exam, but they were able to recover and learn from the experience so that they could cope with it effectively the next day. It also demonstrates the important point that crying is not always accompanied by increased cortisol.

So how stressful would sleep training be if a child is in their own room with reassurance from a parent? I’m really not convinced that it could be as bad as people say. If I had to guess, I would predict that age-appropriate sleep training in a familiar and supportive environment would cause a small increase in cortisol for a few nights, but not chronically.

There are studies that have looked at cortisol levels in babies that were separated from their mothers briefly. 9 month old babies were left alone for 30 minutes with a stranger in a lab which caused a 20-40% increase in cortisol. That’s minor considering it fluctuates 10x that much on a daily basis. Other studies show that by 12-18 months, maternal separation does not increase cortisol.

Let’s consider a stressful situation that’s actually comparative to sleep training: starting daycare! This involves a big change in their routine and prolonged separation from an attachment figure. This can cause an increase in cortisol EVEN IF mom stays for the first two weeks.


What’s significant to remember?

  • I won’t make you use Cry It Out for your sleep training method - but there will be crying involved if we want to see change because it’s how babies communicate how they feel. We don’t stop them from expressing their feelings. We support them through it and give them opportunities to grow.

  • Crying doesn’t necessarily mean a spike or an increase in cortisol

  • Cortisol is a normal and necessary part of our body’s homeostatic physiological functioning.

  • When we look at the longitudinal, reputable research observed across multiple cultures and geographical locations around the world, sleep training and teaching independence around sleep is a good thing for many significant benefits. Introducing opportunities for independence and also promoting sustainable sleep habits - giving children the chance to settle on their own - has no emotional impact long term.

  • The best conclusion we can make from longitudinal studies (see links above) is the most significant impact of sleep training in a home is the positive affect it has on maternal mental health - moms feel like they have the energy and ability to show up better for their children and provide the support and care they need when they are not sleep deprived.

Many of the links and information seen in this blog can be found on Heaven Sent Sleep’s blog and The Peaceful Sleeper’s blog. Thank you for being here!
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