Dangers of Leaving Baby to Cry It Out (CIO)

By Margaret Chuong-Kim
Read more from Chuong-Kim at Dr. Ben Kim's homepage.

Among parents of infants these days, there is constant debate about how to respond to a baby’s cries. On one hand, there are proponents of the “cry it out” method, where the baby is left alone to cry in the hopes that he or she will eventually stop. On the other hand, there are the “attachment parents” who respond immediately to their crying babies and attempt to soothe them using various methods including holding and cuddling. While the cry-it-out method (CIO) has been popular in previous years, attachment parenting (AP) is gaining a foothold among new parents today. Results of studies in psychology indicate the AP approach to crying is most likely to result in an emotionally and physically healthy child.

Attachment theory originated in the late 1960s when psychologist John Bowlby postulated that a warm, intimate relationship between caregiver and infant is necessary for optimal health as well as for basic survival. As such, each individual is born well-equipped with reflexes and instincts for interacting with their primary caregiver, which is often times the mother. For example, infants quickly learn to recognize and prefer both their mother’s voice and smell. As babies develop some locomotor control they display their desire to be close to their caregivers by reaching toward their mother or father to be picked up or by crawling toward them. From an evolutionary perspective, these behaviours have survival value. Babies who lack such attachment behaviours will stray from their caregivers and are more likely to get lost, attacked, and perish. An infant’s cry is also intended to increase the likelihood of its survival, as a mother’s instinct is usually to go to her child at the first sign of distress.

We live in an age where we can know that the baby is safe in another room, despite the loudness of his cries. Does this mean we should leave babies to cry on their own? CIO proponents often advise that babies left to cry will eventually stop, and the duration of future crying bouts will decrease. What are the emotional consequences of crying for the infant when she is left unattended? Bowlby and colleagues initiated a series of studies where children between the ages of one and two who had good relationships with their mothers were separated from them and left to cry it out. Results showed a predictable sequence of behaviours: The first phase, labeled “protest”, consists of loud crying and extreme restlessness. The second phase, labeled “despair”, consists of monotonous crying, inactivity, and steady withdrawal. The third phase, labeled “detachment”, consists of a renewed interest in surroundings, albeit a remote, distant kind of interest. Thus, it appears that while leaving babies to cry it out can lead to the eventual dissipation of those cries, it also appears that this occurs due to the gradual development of apathy in the child. The child stops crying because she learns that she can no longer hope for the caregiver to provide comfort, not because her distress has been alleviated.

Do babies cry more when they are attended to? A 1986 study concluded just the opposite: the more a mother holds and carries her baby, the less the baby will cry and fuss. Cross-cultural studies also show that parents in non-Western societies are quicker than parents in Western societies to respond to their crying babies, and babies in non-Western societies cry for shorter spans of time. Caregivers in 78% of the world’s cultures respond quickly to an infant’s cries. For instance, Efe caregivers in Africa respond to a baby’s cries within ten seconds at least 85% of the time when the baby is between three and seven weeks, and 75% of the time when the baby is seventeen weeks. !Kung caregivers respond within ten seconds over 90% of the time during the baby’s first three months, and over 80% of the time at one year. In contrast, American and Dutch caregivers have been found to be deliberately unresponsive to an infant’s cries almost 50% of the time during the baby’s first three months. Infants in non-Western societies have been found to fuss just as frequently as those in Western societies, but due to the prompt response of caregivers in non-Western societies, the overall cumulative duration of crying is less than what occurs in Western societies.

According to attachment theory, many babies are born without the ability to self-regulate emotions. That is, they find the world to be confusing and disorganized, but do not have the coping abilities required to soothe themselves. Thus, during times of distress, they seek out their caregivers because the physical closeness of the caregiver helps to soothe the infant and to re-establish equilibrium. When the caregiver is consistently responsive and sensitive, the child gradually learns and believes that she is worthy of love, and that other people can be trusted to provide it. She learns that the caregiver is a secure base from which she can explore the world, and if she encounters adversity she can return to her base for support and comfort. This trust in the caregiver results in what is known as a secure individual.

Children who do not have consistently responsive and sensitive caregivers often develop into insecure individuals, characterized by anxious, avoidant, and/or ambivalent interactions. Long-term studies have shown that secure individuals, compared to insecure individuals, are more likely to be outgoing, popular, well-adjusted, compassionate, and altruistic. As adults, secure individuals tend to be comfortable depending on others, readily develop close attachments, and trust their partners. Insecure individuals, on the other hand, tend to be unsettled in their relationships, displaying anxiety (manifesting as possessiveness, jealousy, and clinginess) or avoidance (manifesting as mistrust and a reluctance to depend on others). North American parenting practices, including CIO, are often influenced by fears that children will grow up too dependent. However, an abundance of research shows that regular physical contact, reassurance, and prompt responses to distress in infancy and childhood results in secure and confident adults who are better able to form functional relationships.

It has been suggested in the past that CIO is healthy for infants’ physical development, particularly the lungs. A recent study looking at the immediate and long-term physiologic consequences of infant crying suggests otherwise. The following changes due to infant crying have been documented: increased heart rate and blood pressure, reduced oxygen level, elevated cerebral blood pressure, depleted energy reserves and oxygen, interrupted mother-infant interaction, brain injury, and cardiac dysfunction. The study’s researchers suggested that caregivers should answer infant cries swiftly, consistently, and comprehensively, recommendations which are in line with AP principles.

CIO supporters tend to view their infants’ cries as attempts to manipulate caregivers into providing more attention. Holding this view can be detrimental to the immediate and long-term health of the baby. In the field of cognitive psychology there exists the premise that our thoughts underlie our behaviour. Thus, if we think positively about an individual, our behaviours toward them tend to be positive as well. Conversely, if we think negatively about an individual, we will behave correspondingly. Consider people in your own life whom you consider manipulative – how does that perception influence your behaviour toward them? It is unlikely that the interpretation of a manipulative personality will result in the compassionate, empathetic, and loving care of that individual. Infants, quite helpless without the aid of their caregivers, may suffer both emotional and physical consequences of this type of attitude.

When faced with a crying baby, it may be prudent to ask yourself the following questions: Why am I choosing this response? Do I want my baby to stop crying because he feels comforted and safe, or do I want my baby to stop crying for the sake of stopping crying? What is my baby learning about me and the world when I respond in this manner? If I were a baby and was upset, how would I want my caregivers to respond?

For more on 'sleep training,' 'cry it out' (CIO) and 'controlled crying' see resources at:

Campos, J., et al. (1983). Socioemotional development. In P. Mussen (Ed.), Carmichael’s Manual of Child Psychology: Vol. 2. Infancy and Developmental Psychobiology. New York: Wiley.
Craig, G., Kermis, M., & Digdon, N. (1998). Children Today. Scarborough, ON: Prentice-Hall.
Dacey, J. & Travers, J. (1996). Human Development Across The Lifespan (4th Ed). Boston: McGraw-Hill.
DeCasper, A., & Fifer, W. (1980). Of human bonding: Newborns prefer their mothers’ voices. Science, 208: 1174-76.
Gleitman, H. (1996). Basic Psychology (4th Ed). New York: W.W. Norton.
Hunziker, U. & Barr, R. (1986). Increased carrying reduces infant crying: A randomized controlled trial. Pediatrics, 77(5): 641-8.
Luddington, Hoe, S. Cong, X., & Hashemi, F. (2002). Infant crying: Nature, physiologic consequences, and select interventions. Neonatal Network, 21(2): 29-36.
Macfarlane, A. (1975). Olfaction in the development of social preferences in the human neonate. Parent-Infant Interaction. Amsterdam: CIBA Foundation Symposium.
Mikulincer, M., & Shaver, P. (2001). Attachment theory and intergroup bias: evidence that priming the secure base schema attenuates negative reactions to out-groups. Journal of Personality and Social Psychology, 81(1): 97-115.
Miller, R. (2000). Dysfunctional relationships. In R. Kowalski & M. Leary (Eds.), The Social Psychology of Emotional and Behavioral Problems: Interfaces of Social and Clinical Psychology. Washington, DC: APA.
Waters, E., Wippman, J., & Sroufe, L. (1979). Attachment, positive affect, and competence in the peer group: Two studies in construct validation. Child Development, 50: 821-829.


  1. Really interesting... I've been trying a modified "cry it out" in that, if Jane's just whining I'll leave her but if she starts to cry, I'll respond and it seems to be working. I differentiate the two basically by tears and previous experience... during the "whine" if I respond, as soon as she sees me she starts laughing, during the cry, she's just crying so she doesn't stop until I pick her up. It makes me feel good to know that I'm not "spoiling" her. Good post!

  2. Jen, you are basically trying to tell the reader that behavioral modification is okay; the kicker in your comment is when you make sure to enclose the dreaded word in double quotes: 'it makes me feel good to know that I'm not "spoiling" her.'

    Jen, let me ask you this:
    HOW can you "spoil" a newborn with Love and attention ?

    I think you need to put down your books & magazines and start listening to your motherly instincts.

    In peace.

  3. I totally agree that a newborn cannot be spoiled! It is his/her right to have that attention and love! We all love to be hugged and be given attention even as adults so how can we expect a baby to survive without!!
    Research actually shows that babies need more love and comfort than the actual feeding!! For example, I really hate to see parents bottle feeding their baby while still in the stroller. Apart from being dangerous and me being a breastfeeding fan, babies need that touch, they need the feeling of closeness and they show this need by crying!
    I really hate it when some people tell me to put the baby down as soon as they see her in my hands simply because they think i'm spoiling the baby! I really wish i could ban that phrase!!
    Why do I need to put the baby down or to leave her crying for a while? To get the cleaning or cooking done? For me no reason is good enough and now i'm starting to see the results for my patience as my baby is more trusting of me leaving her in her bouncer just for a short period while i cook or hang up the clothes. I still talk or sing to her all the time she's sitting there so that she knows that i'm still giving her attention. When i finish i pick her up immediately and i don't let her to start crying in order to pick her up. This way i feel i get her to trust me more. If she does start crying and i haven't finished my chores i simply put her in a sling and carry her around with me!
    I'm no expert so maybe my methods may not be right but my 3 month baby has really reduced 'crying spells' and everybody is amazed that she is much more attentive and interactive than other babies her age!
    So please be patient and forget about other things, nothing is more important than your baby's happiness! And i think tha a Happy Baby = Happy Mummy and Daddy!

  4. I agree with the post. I never practice Cry-It-Out and have had several family members tell me I'm "spoiling" her because I never "let" her cry.

    Just in Jen's defense however, she did not say that her baby/child was a newborn. I have an 8 month old and co-sleep but if I "responded" every time she whimpered she would never get any sleep! Babies make noise! Not all of the noises they make are crying. I think if Jen is differentiating between crying and sleep whimpers that's ok. My daughter will whimper for literally four seconds and then roll over and not even wake up in the process. But yes, I do and will continue to respond to all her cries. It breaks my heart to hear them, what else could I do!? As a mother, I think it's only natural to respond.

  5. WOW! I ahve always felt the CIO method wrong.. Now I have something to back it up!

  6. I disagree with the CIO method. I co-sleep, babywear, breastfeed, and immediately respond to my 4 week old's cries. I think it's our natural instinct to feel distress when our child cries and it's normal to want to comfort them. I get told that he needs to be put down and it's ok for him to cry, but in my heart I know I'm doing the right thing for my child by responding consistently to his needs. My question is...how do you respond when they are crying in the car or when you are showering? I am a single mom and usually wear him in a sling in the shower or wait until he falls asleep to take a shower , but there are times when I need to shower quickly and he starts crying. He also cries everytime we are in the car and refuses to take a pacifier. Sometimes I will reach back and hold his hand from the front seat or pull over (if possible) and nurse him for comfort, but he still screams when we start driving. Usually he will eventually fall asleep, but it kills me to let him cry like that. Any suggestions? Do you think this will affect him or be detrimental??

  7. I never let my babies cry it out - ever. They were breastfed, carried in slings and co slept and due to that didn't often need to cry. I think it is so important to create a sense of confidence and now my children are 4 and 6 they are highly independent, very happy, able to express lucidly their emotions and rationalise how they are feeling. I like to think of it a simple psychology, of a person feels secure then they thrive, babies have exactly the same gamet of emotions, I find it highly distressing to hear babies screaming and shivering and being left, just cuddle they need contact and reassurance. Obviously we are not perfect and sometimes soothing the babe can be hard and tiring, but I firmly believe that a baby is more content and less like to have a crying bout. If you can;t calm them then maybe they have a poorly ear, or a pain. Most of the time it is a desire to be held and a natural need to be with the parent. A baby cannot be spoiled with contact and affection, quite the opposite a baby deprived of contact can become nervous, withdrawn, anxious and "needy" which is a term I dislike but that many use. A "needy" child is a child anxious that the parent will not return, a child in need of more attention, not less.
    My son travelled really well in the car, but my daughter didn't like it at all. She now gets motion sickness sometimes, so I think that may have been the case when she was under one. I can fondly remember singing "Old MacDonald " repeatedly on long journeys and hand holding while driving. We sometimes used to stop every twenty minutes!
    One of the most effective things for her was classical music played quite loudly.
    I know that it is so distressing and I empathise, but if it helps it soon stopped once she was talking and able to say what she was unhappy about and I suppose more able to understand that the journey was simply temporary.
    For the shower problem, I had a baby swing and would pop on a Baby Einstein DVD which was really stimulating and to my mind a better alternative than me in the shower for 5 minutes and her feeling alone and worried, rather she had lovely music and images.
    It is a such a balancing act, but you sound such a lovely mother with such a positive, natural and a healthy approach.

  8. Can't wait for an answer to the above question. I was so in the same boat and have always joked that 'I am an AP parent... except in the car' :(


  9. Funny how taking care of your babies is now called "attachment parenting" Everyone I know calls it being a mother!

  10. Pete

    I feel the emotions well up inside of me as I remember my early years as a parent. I remember going to a class sponsored by my HMO at the time that was taught by a Pediatrician. I believed I could follow everything he said to the letter and be confident that I was doing the right thing. So, in the mid 1980's when the, 'Cry it Out' method was recommended to me by this board certified Pediatrician in the class he taught I believed it was the right thing to do. When I was home with my infant daughter and she started to cry as long as I knew she was not hungry, or soiled, I would just leave her in her crib. I remember sitting in a chair in another room and fighting all my urges to go and pick her up and hold her to comfort her. I had been instructed by someone I believed to be 'in the know' infallibly in regardd to this matter. No one in the class objected to the way he taught it and the content. Today, I regret not seeking out more information from others and I know I am scarred from forcing myself to not attend to my daughter. She is grown today, and although we don't talk about it, I sometime wonder if she ended up with emotional scars as well. I hope someone reads this and it can prevent them for making the same mistake as a parent. This is on the medical and psychology professionals to get it right before they espouse their advice to new parents!



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