Although many sleep “experts” claim there is no evidence of harm from practices such as controlled crying, it is worth noting that there is a vast difference between ; “no evidence of harm” and “evidence of NO HARM.” ; ;In fact, a growing number of health professionals are now claiming that training infants to sleep too deeply, too soon, is not in babies’ best psychological or physiological interests.

The Australian association of Infant Mental Health advises, “Controlled crying is not consistent with what infants need for their optimal emotional and psychological health, and may have unintended negative consequences.”

Despite the popularity of controlled crying – most parents are led to believe this is their only option – it is not a scientifically evidence-based practice. ;In a talk at an International Association of Infant Mental Health Conference held in Melbourne in 2004, Professor James McKenna, director of the Mother-Baby Behavioural Sleep Laboratory at the University of Notre Dame, Indiana, USA and acclaimed SIDS expert, described Controlled Crying as “social ideology masquerading as Science.”

The “science” behind Controlled Crying and other related regimes is based on the idea that if parents don’t respond when their baby or young child cries, the rewarding effects of this attention will be removed. ; However, this simplistic, “one size fits all” approach doesn’t take into account that as well as the more obvious needs to be kept clean and fed, babies and children are also feeling little beings who have legitimate emotional needs. Or that sleep may be affected by many factors, from allergies or food intolerance (particularly sensitivity to salicylates, naturally occurring chemicals in otherwise healthy foods such as broccoli, grapes, oranges and tomatoes, for instance). Or nutritional deficiency (new research is linking low levels of essential fatty acids to poor sleep patterns as well as hyperactivity and learning difficulties). To new developmental stages – physical (teething), emotional (separation anxiety) and neurological (practising new skills such as crawling or standing as the brain processes information during sleep, rather as we have difficulty trying to sleep after a busy day, a big night out or perhaps as we are starting a brand new job).

According to a policy statement issued by the Australian Association of Infant Mental Health (AAIMHI), “There have been no studies, to our knowledge, such as sleep laboratory studies, which assess the physiological stress levels of infants who undergo controlled crying, or its emotional or psychological impact on the developing child.”

What this means is that despite a plethora of opinions on exactly how long you should leave your baby to cry in order to train her to sleep, nobody has actually studied exactly how long it is safe to leave a baby to cry, if at all.

Babies who are forced to sleep alone (or cry, because many do not sleep) for many hours may miss out on both adequate nutrition and sensory stimulation such as touch, which is as important a nutrient as food for infant development. Leaving a baby to “cry it out” in order 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 a reduced food intake – the result of expending unnecessary energy through crying whilst being deprived of food is likely to be weight loss and failure to thrive.
Paediatrician William Sears has claimed that “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 be “brand new and blue” and often the predisposing conditions are beyond our control, such as trauma due to early hospitalisation and medical treatments. However, if we consider the baby’s perspective, it is easy to understand how extremely rigid regimes can also be associated with infant depression and why it isn’t worth risking, especially if your child has experienced early separation – you too would withdraw and become sad if the people you loved avoided eye contact, as many controlled crying techniques advise, and repeatedly ignored your cries.

Leaving a baby to cry evokes physiological responses that increase stress hormones – crying infants experience an increase in heart rate, body temperature and blood pressure – these reactions are likely to result in overheating – a potential SIDS risk factor.

There is also emerging evidence that increased levels of stress hormones associated with low levels of maternal responsiveness may cause permanent changes in the physiology of the infant’s developing brain. For instance, infant studies by biological psychology researcher Megan Gunnar and colleagues report that the level of stress experienced in infancy permanently shapes the stress responses in the brain, which then affect memory, attention, and emotion. There is also evidence that this altered stress response can predispose children to later anxiety and depressive disorders, and in studies on Rumanian orphans, children with the lowest scores on mental and motor ability tests were shown to be the ones with the highest cortisol levels in their blood.

Controlled Crying 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: One of the saddest emails I have received was from a mother who did controlled crying with her one-year-old toddler. She says,

“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 neuro-biologist Bruce Perry calls the “defeat response.” ; ;When infants are not responded to, they may eventually abandon their crying – the nervous system shuts down the emotional pain and the striving to reach out. Sydney psychologist Robin Grille explains this 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 “freeze” and the infant shuts down. When an infant’s defeat response is triggered often enough, the child will become habituated to this – that is, each time the child is exposed to controlled crying 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” more quickly, not learning a legitimate skill.

The saddest risk of all is that as the baby tries to communicate in the only way available to him, he will learn a much crueller lesson – that he cannot make a difference, so what is the point of reaching out. This is learned helplessness.


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Michael Lamport Commons, Ph.D. Harvard Medical School
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Homeostasis, Stress, Trauma and Adaptation: A Neurodevelopmental View of Childhood Trauma Bruce D. Perry, M.D., Ph.D. Ronnie Pollard, M.D

Stress in Infancy by Linda Folden Palmer, D.C.

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