Crucial Insights: Is Sleep Training Harmful? A Closer Look at the Controversy and Your Child's Health

Crucial Insights: Is Sleep Training Harmful? A Closer Look at the Controversy and Your Child's Health

Crucial Insights: Is Sleep Training Harmful? A Closer Look at the Controversy and Your Child's Health

When individuals express concerns about the dangers of sleep training and its potential harm to your baby, I confidently affirm their lack of understanding. Backed by scientific evidence, I can substantiate the safety and effectiveness of sleep training methods!

Cry it out: safe or harmful?

Critics of sleep training often pull out tired old arguments that leaving your baby to cry will cause stress, negatively impact attachment, and cause emotional and behavioural problems later in life. 

This is simply not true.

In fact, research in the Journal of American Pediatrics suggests cry it out (CIO) or spaced soothing is not only safe but can even be the most effective sleep training method.


The 2015 study found babies in the spaced soothing group fell asleep faster, slept longer, woke up less, and had lower stress levels than the gentler method and the control group.

Not only that, but mums in the spaced soothing group experienced less stress than mums in the other two groups!


All about the research


Let’s take a closer look at the study.

Scientists set out to see if there was evidence to support the common criticisms of sleep training.

The most common are that it doesn’t work, it’s stressful for parents and babies, it negatively impacts parent-child attachment, and it leads the child to have emotional and behavioural problems later in life.  


43 infants between 6-16 months were randomly assigned to three groups. 

  • Graduated extinction (CIO or spaced soothing) – a parent ignores their child’s crying for two minutes initially, gradually increasing the time they stay away from the crying child for up to six minutes on the first night. The idea is to continue gradually extending this period over the next several days. 
  • Bedtime fading – a gentler approach where parents learn the time their baby naturally falls asleep in the evening and then slowly move the baby's bedtime forward by 15mins until the baby falls asleep at that time, moving it again and again until they reach the desired bedtime. 
  • And finally a control group – these parents were simply provided information about sleep.

The researchers determined how much sleep the babies got by looking at parents’ sleep diaries and actigraph measures (sensors babies wear that detect and measure movement).

They measured cortisol levels from the babies’ saliva samples both morning and afternoon to determine stress levels.

Parents self reported on their own stress and mood.


Debunking myths about sleep training


The findings may be surprising to some, but back up what we at Baby Sleep Consultant live by – that sleep training is effective, safe, and helps the wellbeing of the whole family.

Within a week babies in the spaced soothing group fell asleep 13 minutes faster than they had previously -  compared to 10 minutes faster for babies in the bedtime fading group, and no changes in the control group. 


In the spaced soothing group the babies had a very large decline in the number of wake ups over night, while there were no changes in this for the other two groups including the control.


By comparing the parents’ sleep diaries and the babies' actigraph measures, the researchers found that infants in the spaced soothing group still experienced wake ups during the night, but they did not cry out to their parents. Interestingly, the researchers concluded that this was not because they had ‘given up’ as some of our harsher critics may suggest, but because they were able to self-soothe – something we’ve been saying all along!


Spaced soothing did not result in significantly or chronically elevated cortisol levels (stress hormone), and there was no evidence of impaired attachment or the development of emotional or behavioral problems when analyzed 12 months later.

This lack of evidence of impaired attachment or emotional and behavioral problems supports the recent 6 year follow up, which looked at children 6 years after behavioral sleep training, and found no difference in these children vs the control group who received no sleep training.

It's important to note here that cortisol levels were not tested until the day after the night of sleep training, this is because researchers know that what is dangerous is chronically elevated cortisol levels, there is no scientific stress significance in temporarily raised cortisol levels.

If you’ve been putting off sleep training for fear it might harm your child, I hope the science will help put your mind at ease.

Sleep training is safe and effective and really can deliver better sleep for you and your baby.  


Emma Purdue

Emma Purdue

Emma is the owner and founder of Baby Sleep Consultant, she is a certified infant and child sleep consultant, Happiest Baby on the block educator, has a Bachelor of Science, and Diploma in Education.

Emma is a mother to 3 children, and loves writing when she isn't working with tired clients and cheering on her team helping thousands of mums just like you.


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Michael Gradisar, Kate Jackson, Nicola J. Spurrier, Joyce Gibson, Justine Whitham, Anne Sved Williams, Robyn Dolby and David J. Kennaway, Pediatrics June 2016, Behavioral Interventions for Infant Sleep Problems: A Randomized Controlled Trial

Sadeh, A. (1994). Assessment of intervention for infant night waking: Parental reports and activity-based home monitoring. Journal of Consulting and Clinical Psychology, 62(1), 63–68. 



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