The Myth of Controlled Crying
Despite the popularity of controlled crying it is not an evidence-based practice. Professor James McKenna, director of the Mother-Baby Behavioural Sleep Laboratory at the University of Notre Dame, Indiana and acclaimed SIDS expert describes controlled crying as ‘social ideology masquerading as science’. What this means is that despite many opinions on how long to leave a baby to cry, to train her to sleep, nobody has studied exactly how long it is safe to leave a baby to cry, if at all.
Babies who are made to sleep alone (or cry, because many do not sleep) for hours may miss out on both adequate nutrition and sensory stimulation such as touch, which is vital for infant development. Leaving a baby to ‘cry it out’ to enforce a strict routine when the baby may, in fact be hungry, is similar to expecting an adult to adopt a strenuous exercise program accompanied by less food.
Paediatrician William Sears has claimed, “Babies who are ‘trained’ not to express their needs may appear to be docile, compliant or ‘good’ babies. Yet these babies could be depressed babies who are shutting down the expression of their needs. “Babies can indeed have an actual diagnosis of clinical depression”. Often caused by trauma due to early hospitalisation and medical treatments it is also easy to understand how rigid regimes can cause depression. You too would withdraw and become sad if the people you loved avoided eye contact and ignored your cries, as some sleep techniques advise.
Leaving a baby to cry evokes physiological responses that increase stress hormones, heart rate and temperature. These reactions can result in overheating and could pose a potential risk of SIDS in vulnerable infants. There may also be longer-term emotional effects. Babies need our help to learn to regulate their emotions, meaning that when we respond to and soothe their cries, we help them understand that when they are upset they can calm down.
There is also compelling evidence that increased levels of stress hormones may cause permanent changes in the stress responses of an infant’s developing brain. These changes can affect memory and emotion and trigger an elevated response to stress throughout life, including a tendency to anxiety and depressive disorders. English psychotherapist Sue Gerhardt, author of Why Love Matters: How Affection Shapes A Baby’s Brain explains that when a baby is upset the hypothalamus produces cortisol. In normal amounts cortisol is fine, but if a baby is exposed for too long or too often to stressful situations (such as being left to cry) its brain becomes flooded with cortisol and it will either over- or under-produce cortisol whenever the child is exposed to stress. Too much cortisol is linked to depression and fearfulness; too little to emotional detachment and aggression.One of the arguments for controlled crying is that it ‘works’, but perhaps the definition of success needs to be examined. In the small number of studies undertaken, while most babies will indeed stop waking when they are left to cry, ‘success’ varies from an extra hour’s sleep each night to little difference between babies who underwent sleep training and those who didn’t. Some studies found that up to one-third of babies who underwent controlled crying ‘failed sleep school’. To me this suggests that even if harsher regimes work initially, babies are likely to start waking again as they reach new developmental stages or conversely, they may become more settled and sleep (without any intervention) as they reach appropriate developmental levels.
Controlled crying and other similar regimes may indeed work to produce a self-soothing, solitary sleeping infant. However, the trade-off could be an anxious, clingy or hyper-vigilant child or even worse, a child whose trust is broken. Unfortunately, we can’t measure attributes such as trust and empathy which are the basic skills for forming all relationships. We can’t, for instance, give a child a trust quotient like we can give him an intelligence quotient. One of the saddest emails I have received was from a mother who did controlled crying with her one-year-old toddler.
“After a week of controlled crying he slept, but he stopped talking (he was saying single words). For the past year, he has refused all physical contact from me. If he hurts himself, he goes to his older brother (a preschooler) for comfort. I feel devastated that I have betrayed my child.”
It is the very principle that makes controlled crying ‘work’ that is of greatest concern: when controlled crying ‘succeeds’ in teaching a baby to fall asleep alone, it is due to a process that neurobiologist Bruce Perry calls the ‘defeat response’. Normally, when humans feel threatened, our bodies flood with stress hormones and we go into ‘fight’ or ‘flight’. However, babies can’t fight and they can’t flee, so they communicate their distress by crying. When infant cries are ignored, this trauma elicits a ‘freeze’ or ‘defeat’ response. Babies eventually abandon their crying as the nervous system shuts down the emotional pain and the striving to reach out.
One explanation for the success of ‘crying it out’ is that when an infant’s defeat response is triggered often enough, the child will become habituated to this. That is, each time the child is left to cry, he ‘switches’ more quickly to this response. This is why babies may cry for say, an hour the first night, twenty minutes the following night and fall asleep almost immediately on the third night (if you are ‘lucky’). They are ‘switching off’ (and sleeping) more quickly, not learning a legitimate skill.
Whether sleep ‘success’ is due to behavioural principles (that is, a lack of ‘rewards’ when baby wakes) or whether the baby is overwhelmed by a stress reaction, the saddest risk of all is that as he tries to communicate in the only way available to him, the baby who is left to cry in order to teach him to sleep will learn a much crueler lesson – that he cannot make a difference, so what is the point of reaching out. This is learned helplessness.