Resilience in Children

Controlled Crying - Is it safe? (In-depth Assessment of a Recent Study)

Published: 31 May 2016
Controlled Crying - Is it safe? (In-depth Assessment of a Recent Study)

Controlled crying is one of those issues that everyone has an opinion about. Following the recent release of a Flinders University study, the topic has lit up the Internet with social media battles raging about whether controlled-crying is bad for our children.

Let’s take a close look at the research to decide whether this study should be guiding any decisions about whether to encourage controlled-crying as a safe and suitable baby-settling technique.

The study set-up

The researchers compared different approaches to baby “sleep-training” over a 12-month period. Parents were randomly assigned to one of three groups:

Group 1: Fourteen couples and their child were placed in a control group where they were given some basic infant sleep education.

Group 2: Fifteen couples and their child were in a “graduated extinction” group, otherwise known as the controlled-crying group. Parents were instructed to put their infant to bed awake and leave the room within 1 minute. When re-entering the room for a crying baby, they comforted their child, but avoided picking the child up and turning the lights on. (Not sure how comforting that would be to a child!) Each time, they waited longer to return to their infant.

Group 3: Fourteen couples and their child were placed into a bedtime fading group. In this situation, a child is kept up a little later each night so he is increasingly tired when placed into bed. The babies were aged between 6 and 16 months (with an average age of 10 months).

These are small groups. But by the time the three-month mark of the study arrived, groups had halved. We’re now looking at data from about 7-8 people per group. This is not a powerful sample size from which to draw conclusions.

What they did

For a week (pre-treatment), parents kept a sleep diary for their child, and the child wore a sleep monitor. Mums provided info about their personal stress, anxiety, and depression levels. Parents collected two child saliva samples in the morning (usually about 9am) and afternoon (around 3.30pm) for cortisol analysis. Cortisol is a stress hormone. All of these measures were to establish a baseline to see how things changed over time.

Then parents were taught what they were to do for their baby’s sleep. They followed these instructions for three months and parents kept a diary of sleep patterns, while babies wore the actigraph to monitor movement.

And the children participated in an experiment called the “strange situation” (which you can read about here) to assess how securely attached to mum they were at the one-year follow-up.

The outcomes

This is where it gets tricky – and where the media have slipped up. Baby sleep was measured in two ways: parent-report, and actigraphy – the sleep/activity monitor the baby wore.

When parents were asked their perspective on how long it took the baby to get to sleep, there was no difference between groups at the start of the experiment. It took an average of about 18 minutes. At the end of 3 months, parents in the two experimental groups reported their infant was going to sleep in 5-9 minutes while the control group was taking 20! Sounds like controlled-crying and bedtime-fading work.

Parents using controlled-crying said their baby was waking less at night: down from 3 times to 1.5 over the 3-month period. Bedtime fading reduced wakeups by half as well. An insignificant drop was reported for the control group.

So far it looks like crying it out works huh. But… once total sleep time is taken into account, there’s no difference between the three groups. And there were also no differences in the time awake after sleep onset.

Put simply, the study claims that controlled-crying boosts infant sleep, but instead, the numbers show that parents think their baby is sleeping better. It actually isn’t! Any improvement is the same across all groups, and may be simply related to maturity.

Stress for bub

The results here are essentially meaningless. Measuring infant cortisol levels in the morning yielded no differences. All the babies woke up the same. The afternoon cortisol readings were marginally different but not enough to be interesting. Because cortisol was not measured in the “sleep training” process we actually don’t know what was happening to the babies at that time.

Stress for mum

A central reason controlled-crying is advocated is because mums need sleep, and this apparently helps them get there. Not based on this study. While the news articles didn’t tell us this, the study found mums became less stressed in all three groups, but the least positive result was in the controlled-crying group. The bedtime fading group actually had the best results in terms of reduced stress and positive mood.

What did they do wrong?

One of the reasons people get so frustrated with studies is that “you can always find one that supports any position.” This is why it’s such a big deal to be able to really read the data. So here’s what I’m unimpressed with:

  1. Groups this tiny cannot yield meaningful data. They can point to interesting directions for future research and potential trends. But to claim that controlled-crying is safe based on this study is a gross over-reach.
  2. The researchers didn’t control for a range of important considerations including:
    - whether the children were breast
    - or bottle-fed (breast-fed babies wake more)
    - the time they went to bed,
    - the atmosphere in the home (conflict?),
    - where children went to sleep (parent’s room, own room)
    - whether children co-slept
    - illness
    - how parents responded when baby woke up
    - what strategies group 3 used (may not be a real control group)
  3. The stress measurements (via cortisol) were not taken during the baby’s stress period. So we can’t say the extent to which babies were affected. Stress levels will undoubtedly drop by morning.

What does it really mean?

Essentially, the study is an interesting starting point to further research. It tells us that:

  • Regardless of method, the infants are sleeping as long as each other, but if we don’t use controlled-crying, our children may take an extra dozen or so minutes to go to sleep, on average.
  • Mums who use controlled-crying may end up a little more stressed than other mums.
  • Parents who use controlled-crying may believe their child is asleep but s/he is actually awake, but just not making noise – maybe because they’ve learned their parent won’t come to them even if they do cry (although that’s not in the study – just my speculation).

But even these conclusions are tenuous. With under ten participants per group, the study really offers little support for anything at all! It’s simply a pointer to the need for more and better research in the area.

What should I do?

Based on this study, my recommendation is to offer love in a calm, peaceful environment for your child to go to sleep. Our children feed off our energy. Get close to your child. Be responsive. Provide skin-to- skin contact. Breastfeed. Be present and responsive. Stay calm. Be kind.


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