Sleep training study stokes debate on controlled crying

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A study of the effects of sleep training has reignited the debate over the controversial method.


Researchers found that controlled crying methods did not lead to unsafe levels of cortisol stress hormones

A study of the effects of sleep training has reignited the debate over the controversial method.

The trial found two ‘controlled crying’ techniques not only improved sleep patterns for babies but also left their cortisol stress hormones within a safe range (see graphs). In addition, no problems with attachment were identified during the trial or 12 months later.

The research, published in the journal Pediatrics last month, has been criticised for using a small number of families, and concerns have been raised that the practice may prove harmful to babies.

Clinical psychologist Dr Michael Gradisar, who led the study at Flinders University in Australia, accepted the cohort of 43 babies was small, but argued the findings replicated those of a larger randomised trial in 2012.

‘The more parents hear that graduated extinction [controlled crying] may be safe, and hear about bedtime fading, then hopefully more babies and parents can sleep better,’ said Dr Gradisar.

His study, ‘Behavioral Interventions for Infant Sleep Problems: A Randomized Controlled Trial’, used babies aged over six months who had problems sleeping. The paper comments, ‘Infants’ nighttime awakenings typically diminish by the end of the first year of life, however from six months, 16 per cent to 21 per cent of infants continue experiencing nocturnal wakefulness such that parents report […] a sleep problem.’

The authors cite evidence of serious consequences of parental sleeplessness, ranging from depression to violence against children. ‘Thus, evidenced-based treatments that rapidly resolve infants’ sleeplessness while minimizing family distress are vital,’ they add.

The families were separated into three groups including a control group, which was given sleep intervention information. Parents in the ‘graduated extinction’ group waited two minutes before comforting their baby on night one, increasing the wait over time to a maximum of 35 minutes. Those in the ‘bedtime fading’ group delayed taking their baby to bed by 15 minutes, and increased the delay incrementally.

‘Compared with the control group, large reductions in nocturnal wakefulness resulted from each treatment,’ concluded the paper. ‘Despite assertions that extinction-based methods may result in elevated cortisol, emotional and behavioural problems, and insecure parent-infant attachment, our data did not support the hypothesis.’

Expert view 1

Professor Helen Ball of the Parent-Infant Sleep Lab at Durham University said the ‘very small’ size of the study meant ‘the results are very preliminary and should not be relied on for recommendations’.

Professor Ball made a distinction between ‘cry it out’ – leaving infants in distress for long periods – and the method under discussion. She said, ‘Cry it out is the harshest of the sleep training methods, and the one that is most heavily criticised for causing babies to experience prolonged abandonment and provoking the “shutdown to survive” response.’

She advised parents to ‘educate yourself about the normal range of variation in infant sleep – there is huge range in “normal”.

‘Consider whether the baby has the problem or the parent – the parent’s expectations may need adjusting or they may need some support.

‘It is possible that you may be able to encourage your baby to fall asleep more quickly or wake less frequently after six months of age using one of these techniques [in the research], and the effects may last a couple of months. However, parents should not rush to implement either of these “training” methods in the wake of this publication. It is a tiny increment in knowledge shared for the benefit of other researchers – not as a guide for parents.’

Expert view 2

Research scientist Dr Suzanne Zeedyk said the finding that the babies in the study did not suffer ill-effects didn’t mean there would be no consequences for others.

Dr Zeedyk said, ‘This research is saying that, for some children, it probably isn’t dangerous.

‘For others, it may be more troubling – and that depends on lots of other factors during the day.’ These include how long infants spend in childcare, parental stress and other issues such as bereavement.

Dr Zeedyk suggested that parents should not feel obliged to follow any particular method in order to ‘do the right thing’.

She said parents should try different ideas, including the techniques described in the study, while bearing in mind that ‘parents benefit when they listen to what their baby is telling them’.

‘Everything they do – including the way they respond at night – is impacting on their relationship with their baby,’ she added. ‘You don’t have to be perfect. All you have to do is focus on building trust within your relationship with your baby.’

Dr Zeedyk said crying at night should be understood not as a ‘bad behaviour’ that should be ignored, but a ‘request’. By ignoring their babies’ cries, parents can feel guilt and ‘their distress is picked up by the baby’, she added.

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