The evidence on babies, sleep and crying

I’ve still got babies on the brain as I refresh my memory on how to care for a newborn. By the time they were two months old, my two older children were learning to sleep in their cribs. That meant letting them cry and learn to settle themselves when I knew all of their needs were met. So I was curious to read some recent media reports about the evidence on “crying-it-out.”

A new summary released this summer in the journal Clinical Lactation makes the case that crying is too stressful for babies, and can actually harm their brain development. The article cites one study of 25 infants that found no decrease levels of cortisol – a stress hormone – in the brains of infants who went through a five-day sleep training program where they cried themselves to sleep. In other words, the babies’ cortisol levels remained constant on the nights they cried compared with the nights they fell asleep without crying.

A well-researched article in Slate magazine points out that the babies were being monitored in sleep labs instead of their own homes, which likely elevated their stress levels. Further, this study did not include a control group. In other words, they didn’t measure the cortisol levels of infants not experiencing sleep training.

With a little more digging, I found a comprehensive systematic review on the topic in the journal Sleep. The review – pulled together by the American Academy of Sleep Medicine – included 52 studies on behavioral treatments for night wakings in young children. The findings show that 94 percent of children in the studies improve their sleep habits with behavioral interventions.

The take-home message: Letting a baby fall asleep on his or her own isn’t the right choice for every family. But if you think it’s something you’d like to try, there is no evidence that it causes harm.


  1. Shireen says:

    So sad that this thinking is so prevalent amongst educated people.
    “That meant letting them cry and learn to settle themselves when I knew all of their needs were met”.

    Please, please if anyone reads this blog and is deciding whether to sleep train a 2 MONTH OLD baby…Does a 2 month old baby have needs other than physical needs? Of course they do! They need touch, cuddles, responsiveness. They are not a tamagotchi! They need more than food and nappy changes. This is the when their tiny brain is wiring itself fastest, and we know that early responsiveness is key to wiring the brain properly to respond to later stressors appropriately.

    And this is taking aside the fact that actually, 99% of 2 month olds need feeding at night. What a dreadful lack of empathy there is in our society to be able to ignore the cries of a tiny helpless infant.

    • Fiona says:

      Who are these people who suggest sleep training a 2 month old baby? I only here this from the anti-sleep training brigade. Perhaps there are some who do that and i agree it’s not right. In the UK we get told to feed babies ‘on-demand’ day and night for the first 6 months, and the baby should sleep in a safe cot beside your bed, after that they are bigger and can sleep through the night without needing fed so from then on you can use the sleep training techniques. I sleep trained my babies from 7 months on wards, according to the UK recommendations, i wouldn’t dream of doing it to a newborn. I think people take this method out of context and get their knickers all in a twist, it’s not supposed to be for newborn babies.

  2. Marianne says:

    I have a 6 1/2 month old who was born 6 weeks premature but healthy. Only thing he didn’t have was a suckling reflex at first. I wanted to breastfeed him so badly that I pumped all hours of the day and night for the first couple months and was soon able to go to breastfeeding 100%, something that has been difficult to do (be on demand as any breastfeeding mother knows) but I was proud of this and loved the bonding experience. Sleeping early on wasn’t difficult for him simply because he was premature and needed it developmentally. But as soon as he got close to full term, all the preemption that he was the perfect angel and we were seemingly pretty good parents, meeting most of his demands became parents of a baby like any other. Although we welcomed his louder cries, meaning he had more of a voice and lung capacity with which to speak, and he still slept pretty consistentry for the first 4 or so hours of the night, he would want to nurse the rest of the night and I gratified this request, having found a comfortable laying down position [against medical advice and people in my family. I just didn’t talk about it with them and found that position was safe for him.) It was still rough though, since the rest of the day until he was 5 months old would cry and cry if I put him down.

    We were happy to find around that time, with breastfeeding and now just rocking, we’re able to put him down for 2-4 naps during the day and I can even feed him once and put him back to sleep at night and on a good night averaging 8 hours for both of us. But, even if this sounds good, we struggle with setting limits and offering him a routine he can trust and depend on because I am struggling with what he needs and am caught squarely between both methods since he seems to have regressed and despite soothing him to put him down wakes immediately and cries until I pick him up. I think I’ve been consistent, but his crying tears at my heart strings and I watch the clock until I can pick him up again. I am not putting him down and letting him cry because I’m lazy, but because I know I’m exhausted and can’t always be there for him (although I try to be most of the time). I just want to be the kind of mother that is consistent and available and I really don’t know which way to turn, even having tried to find scientific peer reviewed research, especially longitudinal in nature. I wonder how to make breastfeeding work even if I was able to get him to sleep through the night. I’m just starting to introduce solids but most of his nutrition needs to still come my milk at this point as I understand.

    There is just souch conflicting information out there that seems mutually exclusive and shame based on both sides. I am in the midst of it in a very personal way just wanting to do the best for my child and am at my wits end. Although I think tolerate nuance and learning what works for our family as we go through it, it is getting quite taxing when he cries to not have a clear direction and end up sending him mixed signals after all is said and done. Is it even possible to have a middle ground that sways with the course of time and circumstance/temperament? IEven if there was, that is probably what I’m doing now…which is more perplexing than it is relieving when it comes parenting. Afterall, we all have to stand somewhere. Responses to the true predicament at the heart of the matter of loving our children is welcome. Sorry for such a long story and thank you for taking the time to read!

    • Just another mom says:

      Marianne, you are doing amazing. I have a 3.5 year old that was the same – BF to sleep, BF for soothing, BF for naps. I did not sleep train or let him cry it out but that is what was right for me. It was extremely challenging but that was what I chose for me and my child. The consistency is that you love him no matter what and he knows that. You know what your child needs because you are already putting his needs above your own from what it sounds like but you still need to take care of yourself. The fact that you are “stressing” out about this shows that you care, love him, are an active parent doing what’s right for him, and thinking critically about what is best for your child from moment-to-moment. You are already doing an amazing job, just know that. I can tell from what you wrote that you care so much and as much as we want a baby manual telling us how to raise this little being, there isn’t one because you are writing a page each day. And I promise you that YOU know your child best — you will continue to learn his temperament if you haven’t already. Each child is different and what works for one will not work for another. You are an intelligent woman (based on how well written your response was) so stop doubting yourself — I can see the self doubt in your response as well. AND you do not need to defend your position with anyone, not even your well-meaning family. I co-slept with my son because of the BF’ing from day 1 and he is fine. You’re taking all of the precautions I’m sure. I know this is not what you want to hear but it does get better (the sleep part), other things just get “different” because then there’s the toddler meltdowns, etc but it gets better. I didn’t believe it would but it does and I had a challenging child, to this day, but I know him and his temperament which is so great — his meltdowns just make me smile now because it’s so endearing what they lose their cool about — I try not to laugh but it can be quite amusing — especially when you put the “wrong” shirt on him and he HAS to wear his red dinosaur shirt
      …That doesn’t exist in his wardrobe. You will still lose your cool at times but it is so much more fun in the toddler years. Wish you all the best, know you are doing an amazing job, and look forward to the beauty of raising this unique being. Do not doubt yourself — don’t look back (don’t guilt yourself for what you cannot change), just look ahead to all of the amazing things to come.

      • Marianne Joiner-Hughes says:

        Wow, I just read this almost 20 months later just having stumbled back upon it! Thank you for your kindness, affirmation and truly seeing me, Just another mom! I have hindsight, now. Things are challenging but in wholly different ways…which goes to show that he is maturing and we did our job for that time in our life. Now, I want to ween him but he still wants to BF. I go with the flow though, and know there will come a time when he is ready! Yet again. From a mother to a mother, best wishes!!!

  3. Jennifer R says:

    You can’t find evidence of harm if you’re not looking for it. You can’t see negatives if you’re only looking for positives. Where are the long-term IQ studies, the studies on brain function, emotional regulation, and attachment? Why hasn’t anyone compared children who were actually parented to sleep vs. children who were consistently left alone to cry over a significant period of time to see if it had any effects on their behavior in school, and as adults? The studies don’t look at those factors. Why not?

  4. Kids Nook says:

    Like Rowe said… I saw both sides of the coin but then our son developed (we developed would be more accurate) wrong sleeping associations. He thought that he had to be breastfed in order to fall asleep. This resulted in him waking up every hour and a half and screaming his lungs out until he would get breastfed.

    We had to sleep train him and the most important thing I see that came from sleep training our first born was that stress levels dropped significantly within weeks after our son started to sleep all night. My wife wrote an article about our experiences called Every child can learn to sleep

    • Melissa says:

      Kids Nook, you write, “our son developed (we developed would be more accurate) wrong sleeping associations. He thought that he had to be breastfed in order to fall asleep.” You’re giving yourself credit for developing instincts that actually took millennia to develop. All human babies, all primate babies for that matter, have instincts to nurse to sleep, and to sleep near their mothers. All of these babies naturally grow out of this stage with no intervention at all. In recent years, many authors have made a lot of money by defining normal baby behavior like this as a “problem” and promising to solve it.
      Your wife’s article leaves out some details. After she stopped breastfeeding at night, was she able to continue breastfeeding for the two-year minimum recommended by the World Health Organization? Or did CIO interfere with breastfeeding and lead to early weaning, one of the CIO-associated health problems mentioned in one of my earlier links?
      Her article makes the usual unfounded assumptions. You both seem to assume, based on no evidence I can see, that if both parents are sleeping soundly, by definition not paying any attention to the baby, and the baby isn’t crying loudly enough to bother them, then that baby is “asleep.” How do you know this? You’re assuming that the baby has somehow learned to self-soothe instead of simply lying there in hopelessness and despair, not bothering to call for help. There’s this odd assumption that babies can automatically learn to meet any needs that the parents decide to stop meeting. If parents stop soothing the baby, the baby will self-soothe, if parents stop feeding the baby, the baby will self-feed, if parents stop changing diapers, the baby will self-diaper, etc. These all make an equal amount of sense. Maybe I shouldn’t be giving you ideas.

  5. Ida says:

    For an “evidence-based” blog I am thoroughly confused by the lack of evidence. A range of new studies are proving that babies should be close to their caregivers. Please show me the evidence that this need suddenly disappears at night.
    Also, at 2 months a child still needs to be fed at night. At least according to the studies I have read. Please show me the evidence that you based your decision on.
    Also, here is a good collection of the research done on infant sleep by an independent researcher:

  6. Rowe says:

    I can see both sides of the agument but I flip-flop with CIO. In the end, I chose to err on the cautious side as a parent. Just like most parents try to prevent their child from falling or comfort them when they’ve hurt themselves, why wouldn’t you comfort them when they cry or prevent them (as much as possible) from potential future psychological issues/mental illness, related to brain development, as an adult? Being a parent is about being unselfish and caring for this helpless little being that you brought into the world, not about the parents comfort. As an adult, we are better equipped to deal with the stresses of caring for a newborn — maybe we as a society need to be stronger mentally and physically for our children? Mental illness in youth has been increasing…don’t you ask yourself why? Why do these seemingly “good kids” in their early 20’s go on mass killing sprees? Don’t tell me its just because they were bullied…which some of them were not. Many kids are bullied but not all murder in cold blood. They come from good loving homes, with both parents present, so what is it? They’re so young — its not like they have all experienced traumatic events (ie. war, loss) in their lives? Could it (not saying it is) be due to the stress on the brain during this most critical brain development phase — and then combine that with bullying or other factors? Maybe not, but why risk it?

    • Terri Mulhern says:

      It is important to understand that your child does not need comforted every time they cry, and if you run over tot them every time they cry they learn that crying = attention and loving from adults. Then they begin crying every time they are put down or left to play on their own. In addition, comforting your child does not have to come in the form of picking them up. You can sing to your baby, talk to your baby, interact t with your baby from across the room while folding laundry. Your responsibility as a parent is to raise a well-adjusted, loving, contributing member of society, not to make sure your child’s every waking moment is happy,happy, joy, joy……

      • Cynthia says:

        You cannot give your child to much love. Remember that.

        • Carla says:

          Yes, yes, you can. Giving your child everything they want is the most insidious form of abuse.

          • Ida says:

            You cannot spoil a child with love and respect. But you can spoil it with material things. Those are completely different things. Giving unlimited and unconditional love does not mean not setting boundaries.

          • Melissa says:

            Wow, way to change the subject! No one is advocating giving children “everything they want.” There is no equivalence between hugging a crying baby and letting a toddler run into traffic just because he wants to.

      • Ida says:

        Please show me the evidence that children does not need responsiveness for their cries. Or, more like it: do not benefit from responsiveness.
        What you are saying might be true for a 2 year old who is testing you. But not for a baby. A babies cries all mean something.

        • Kristin says:

          Why not rather focus on the appropriate sleep needs of babies and whether they are getting the uninterrupted and healthy sleep that they need for good health and well-being! We did sleep training with both of our boys and it lasted a night or two and they are far from having psychological damage, know they can count on us, their parents, for anything they need but also understand their own sleep needs and have a routine that guarantees them both the sleep that they need to grow and develop properly.

    • Nick Duents says:

      “Mental illness in youth has been increasing…don’t you ask yourself why? Why do these seemingly “good kids” in their early 20’s go on mass killing sprees? ”
      Exactly, and – surprise! – it correlates with increasing popularity of attachment parenting. Suspicious, isn’t it? The earlier babies learn to wait and self soothe the better for them and their mental skills. And unlimited attention of parents 24/7 doesn’t contribute much to these skills.

  7. Pete says:

    This large, longitudinal, control grouped study published in medical journals and subject to peer review shows that controlled crying is safe. It tested infants after 10 months, 1 year, 2 years and 5 years and found no increase in cortisol levels, psychological problems, behavioural problems or bonding. It is endorsed by the National Health Service:
    All other “evidence” I have come across against CIO are studies for other conditions such as Prolonged Crying, Chronic Neglect, sexual or physical abuse, children in care etc. In other studies of rats and other animals the authors state that they should not be extended to humans. Besides they aren’t really applicable as animals don’t sleep train their young. These articles almost always appear on the attachment parenting blogs and are very dishonest scientifically. Unfortunately, some news outlets have reported based on their claims which give them some undeserved credibility.

    Aside from the scientific evidence, if we soberly consider how resilient humans are and have had to be, it doesn’t make sense that a few hours of crying is going to make any significant difference.

    Please post links to any longitudinal study, published in a medical journal and subject to peer review that shows that controlled crying is harmful as we are thinking of sleep training our baby. Although if one existed I think I would have come across it by now.

    Many thanks and good luck with whatever parenting style you choose.


    • Melissa says:

      Pete, you seemed to have missed some key points in the article you linked to (and the original paper linked to that.) the researchers found no significant difference between the two groups by any measure, including measures of sleep problems. The CIO group slept no better than the control. Putting aside questions of safety for a moment, didn’t it strike you as odd that there was no evidence of efficacy either? I’m surprised that the pro-CIO crowd is presenting this article as if it supported their point.
      If, after reading this paper, you still believe CIO is effective, I hope you’re wondering what these researchers did wrong. There are plenty of possibilities. The fact that they started with such a small sample size (much smaller than what would be required to prove the safety of a drug, for instance) is one possibility. Then about a third of their subjects self-selected to drop out of the study. But perhaps the worst problem is that there’s no proof that the CIO group actually all used CIO at all, or that the control group didn’t use CIO. They were ADVISED to use or not use it, but I’m sure health professionals advise their patients to do a lot of things, from quitting smoking to losing weight. That doesn’t mean their patients actually do these things. These researchers couldn’t even get a third of their subjects to show up to complete the study.
      Get back to me if you find a paper that actually studies what it claims to.

      • Pete says:

        I don’t think its controversial that CIO or controlled crying actually works if done properly. This week we “ferberized” our first born. She cried for an hour the first night, 30 minutes the second and less than 10 the third. She now usually doesn’t cry at all or for less than a couple of minutes and hasn’t woken up once in the night. This is typical.

        A bigger sample size is always better but obviously much more expensive in a complex 5 year long trial like this. However, it by far the biggest, most longitudinal study on controlled crying that has been done.

        Whilst I would prefer all the families stay in the study it doesn’t surprise me that a lot drop out over 5 years. I don’t see how you can force them to continue to participate. This is always a problem for longitudinal studies. I also don’t see any reason why this would influence the results other than reduce the sample size.

        It would also be much more expensive to pay specially trained nurses to spend a week at each family’s house to check that they are following the crying out method.

        It isn’t for me to prove that controlled crying ISN’T harmful but for critics to prove that it is. Although it doesn’t surprise me that scientists aren’t interested in spending 5 years trying to prove that letting a baby cry for an hour or two over a week is going to cause lasting physical or psychological damage. Such an insignificant intervention isn’t going to make any difference.

        Good luck with whatever parenting choices you make.


        • Melissa says:

          Pete, you say that CIO works “if done properly.” However, in the study you cited as support of CIO’s presumed safety, CIO did not actually work to improve the sleep habits of the babies in the presumably CIO group. Could you please admit that this study does not prove or disprove anything about CIO, since it clearly was not done properly?
          Now that it’s clear that the study you cited does not actually support your claim that CIO has been proven safe, I see that you’re changing your tone, and saying that it isn’t your place to show safety anyway. Then why were you attempting to prove safety before? Did you briefly have a concern that CIO might be dangerous, but you’ve given up that concern because you couldn’t find any evidence that supported the answer you wanted?
          When you proudly say how little your baby cries, you seem to have missed the point that a quiet baby is not necessarily a content or asleep baby. A quiet baby may have cortisol levels just as high as a crying baby’s. A very stressed baby may simply have given up trying to communicate her needs to her parents. That doesn’t mean her needs have gone away. This is the equivalent of the police proudly announcing that they’ve lowered crime rates by never answering when people call them for help. People will eventually learn not to bother calling the police, but the reduction in phone calls tells us nothing about a reduction in crime. A reduction in crying caused by ignoring cries tells us nothing about a reduction in stress.
          The potential for stress-induced harm from CIO lies not in the extra few hours of crying it adds to a child’s life, but in the unknown number of hours of silent stress that it adds.

          • Fiona says:

            Melissa, cortisol levels naturally fluctuate in response to environmental factors. There is no evidence to suggest that raised cortisol from sleep training is harmful in the first place. Cotrisol only becomes a problem when it is consistently high over a prolonged period of time in response to chronic stress, such as if a child is being abused or neglected. Sleep training is not child abuse. Stop being an alarmist.

        • Ida says:

          I am sure it “works” if your goal is to get the baby to stop asking for your attention. But what are the long term effects of teaching someone so young, and in the middle of critical brain development that no one will come when they ask for help?
          Children cannot “soothe” themselves until around 2 years, due to their frontal cortex being immature before then. So the lesson learnt after CIO is not the popular myth (in the US) of “self-soothing”. So what happens to the child? I prefer to err in the side of caution with my own children.

      • Terri Mulhern says:

        I am a mother of 8, 28 year childcare veteran and published author on parenting and childcare. I am here to tell you there is a difference in the sleep of CIO babies and AP babies, and it does not go in the AP parent’s favor. Children who are CIO sleep longer and better, and so do their parents, which make for a more rested and loving relationship during waking hours. I have observed over 600 children, which is enough for a very significant study, both in a center and in-home environment. I spend 10-12 hours of daytime with the kids I care for, which is far more time than their parents, and my knowledge is based on actual care and observation, not on studies done in Ethiopia and Africa on children who were severely neglected and living in 3rd world conditions your child will never see. How did my kids turn out, you ask? They have all been honor roll, top 3% in standardized testing, hold down jobs and get promoted, do well in college, have loving relationships with each other even as adults etc…. So no matter what I have evidence that my techniques have been successful over multiple children over multiple years. Stop letting this attachment parenting fad scare you into sleep deprivation, poor health and complete subservience to someone you should be parenting. Read the AP boards, and see if you can finds one parent who isn’t venting about being exhausted, frustrated and a**-kicked by their toddler.
        In other words, time to be a parent, and sometimes no is the answer.

        • Cynthia says:

          Attachment parenting isn’t a fad CIO is. What kind of mother lets her babies cry to sleep….a lazy one. Babies are designed to wake up in the middle of the night. You are essentially training your kids to not cry when they need you.

  8. Fiona says:

    Where is the evidence that controlled crying sleep training methods causes any long term negative effect on the brain? There is no evidence to support that. There is evidence with shows sleep training to be beneficial because it gets babies into a healthy sleep pattern.
    The only thing i would say, coming from the UK not the US, is that our recommendations are that your baby sleeps in your room for the first 6 months because of the risk of cot death. Therefor sleep training is not recommended until baby is over 6 months old. My kids were about 7 months old before they were in their own room. I do think 2 months is too young because of the risk of cot death and because baby still needs to be breastfed on demand day and night at that age and stopping night feedings will effect your supply and baby may not get enough milk. But i am not convinced sleep training causes any lasting negative effect on the child’s brain, there is no evidence for that.

    • Fiona says:

      I have read several articles online about raised cortisol levels from excessive crying damages your babies brain, but when you look at the studies in the references they do not say that at all. These articles are just peoples opinions based on poorly conducted studies. I found some which were taken from social services on cortisol levels in severely abused and neglected kids, nothing to do with sleep training, and other studies preformed on mice and rats, not on people. The people writing these articles are usually advocated of attachment parenting so they are obviously looking for anything they can get to support their view, and that means cherry picking studies and twisting the results to fit their predefined view. That is bad science.

      • Fiona says:

        Show me your evidence and ill be happy to pick it apart 🙂 Or, if it’s genuine i will happily change my mind in light of the conclusive evidence.

        • Melissa says:

          Fiona, you say, “On the contrary, the evidence supporting sleep training, which is much more extensive, shows time and again no negative effects on the infant.” Really? Where is this evidence? Every pro-CIO paper I’ve seen (such as the “comprehensive systematic review” linked above) looks only at efficacy, and doesn’t actually look for negative effects on the infant at all. Or if they do look for negative effects, they “look” for these with useless measures, such as asking the parents to fill out a survey expressing their opinion about whether their parenting choices harmed their babies or not. Even CIO’S supposed efficacy is often supported by nothing more than parental surveys like this, not actual objective measurements of infants.

          Did you read the article I linked to before? Here it is again:
          A couple of quotes:
          “Decoupling feeding from sleep in infants younger than six months was associated with increased breastfeeding failure.
          Rigid, scheduled sleep and care in the early months is associated with three times the risk of behavioural problems at six months and twice the amount of crying as infants with cue-based care.”
          Another article here:

          • Fiona says:

            Hi Melissa,

            Yes i did read that link and it doesn’t saying anything about brain damage either. I have read studies which followed up on the children years later and found they were all normal, same as the control group. I still have not seen any studies showing sleep training causes brain damage in children, if you know of any please give me the link so i have have a look.
            The pages you have linked to are not scientific papers, they are peoples blogs based on their predefined beliefs and they are cherry picking studies to make a case against sleep training. I’v said this before. I also said before that in the UK it is not recommended that babies under 6 months old are sleep trained because it can interfere with breastfeeding and because of the risk of cot death, they recommend baby sleeps in a cot beside mum for the first 6 months. So i do agree with the studies shown in this blog in relation to breastfeeding etc, but when it comes to cortisol causing brain damage during sleep training there is still no evidence for that.

          • Fiona says:

            Hi again Melissa,
            I was just going to add – If it was true that sleep training caused brain damage then where are all the brain damaged children and adults? Because a lot of parents use this technique we should expect to see an unusually large rise in brain damaged people since people first started sleep training their children. And this is not the case.
            There has been an increase in diagnoses of autism, ADHD and other similar conditions, but this is because doctors are getting better at diagnosing people and the spectrum has widened on what is considered to be milder symptoms of these conditions, so a lot more people are being diagnosed today than they were say, 20 years ago because doctors are better able to diagnose these things today than they were before. This still does not show any link between sleep training and brain damage, as i have just explained, coloration does not mean causation.

            Everyone wants to find explanations for everything, they want something to lay the blame on, but sometimes shit just happens and it’s nobodies fault. It’s the same as the scare stories around MMR and autism, or any other vaccine scare or GMO scares or computer games, mobile phones, fluoridated water ect people always try to blame something for bad things that happen life. They think everything has a reason, but a lot of the time it’s just random and you just have to accept that sometimes shit happens without reason and there’s nothing you can do about it.

          • Melissa says:

            Fiona, so your argument rests on the fact that there are no stupid, neurotic, or mentally ill people, therefore CIO can’t cause any of these problems. I’m not going to argue that point with you. I’m just going to let your point lie there.
            You then mention the skyrocketing rates of ADHD, autism, etc, and confidently state that CIO has nothing to do with these things. How do you know that? Please, please, show me the studies comparing the rates of these diagnoses between CIO kids and a control group. I haven’t seen any, not even in the “comprehensive systematic review” linked above.
            You’re right that anti-CIO bloggers cherry-pick the studies that show the harm done by CIO. I haven’t seen any cherries at all on the pro-CIO blogs, except for a few rotten ones (with “data” gathered by asking parents to fill out surveys about their own kids, rather than studying the kids directly, for example.) If you have any cherries proving that CIO is harmless, please pick them and share them.

        • Terri Mulhern says:

          You go Fiona! I have asked over and over again where is the evidence that attachment parenting gets positive results. I can’t get on board with all of your logic, but I can say this. The percentage of parents who practice CIO have gone way down, and the AP parents have gone way up. ADHD, Autism, Bi-Polar disorder etc.., should have gone down if it were CIO related, but instead they have gone up. Clear concrete evidence CIO has nothing to do with causing these disorders. I believe there is a connection with the constant movement, lights, sirens and bells/whistles used on infants and the development of these disorders, mostly due to a severe lack of REM sleep, which requires a quiet, motionless environment that the infants of babywearing parents never get, because they are always in motion and surrounded by stimulation 24/7.

          • Ida says:

            I am sorry to say this but the AP style parenting has not gone up as much as you are suggesting. At this point CIO is widespread in the US. Attachment Parenting is unheard of in most places.

          • Jennifer R says:

            Even among many families who profess to use attachment parenting, many end up using some form of sleep training whether it’s the less cry version or the controlled cry version, or even the old fashioned full bore cry it out. I’ve seen it, there are sleep specialists who work with parents who say they practice attachment parenting but that they needed to sleep train to regain their sanity, preserve their marriage, go back to work, etc. I would put the percentage of people who actually consistently soothe their children to sleep as needed at about 0.5% in the US, anyway. Between Dr. Spock, Dr. Ferber, Dr. Weisbluth, and all the other pro-CIO doctors they are bound to run into at least one sleep training doctor. Most parents trust their doctors to advise them about their babies. That’s the root of it.

      • Melissa says:

        Fiona, you dismiss “studies preformed on mice and rats, not on people.” Excuse me? Are you unfamiliar with conventions of safety testing? Are you seriously saying that animal studies don’t apply to humans at all, so everything shown to be harmful to rats is perfectly harmless to human babies? I’ll enlighten you. Whenever a new medical treatment, food additive, etc, is developed, its safety is first tested on animals, such as rats. If it’s shown to harm the rats, it’s not given to people. CIO had been shown to cause elevated cortisol levels in humans. Elevated cortisol levels have been shown to cause harm to other young animals. What aditional evidence do you need?

        • Fiona says:

          Eh hem….. I didn’t say studies on animals are pointless, only that you cannot assume because some effects are shown on certain animals that it would be the same for humans. Different animals produce different results. Humans are not the same as rats, lots of things shown to be harmful or beneficial in rats show the opposite effect in humans. We are not rats.
          Also, the studies i found (which were referenced as evidence for cortisol causing brain damage) preformed on mice and rats used electric shocks to stimulate stress and raise cortisol levels. Are we electrocuting our babies to get them to go to sleep? No, therefor these results are irrelevant to sleep training.
          As far as i am aware, there has been no conclusive studies on humans showing raised cortisol levels during sleep training causes any harmful long lasting effect on the brain. Everyone has cortisol, we need it to function, it’s what wakes you up in the morning and the levels naturally fluctuate throughout the day. Just because cortisol levels are elevated does not make it harmful.

          • Fiona says:

            “CIO had been shown to cause elevated cortisol levels in humans. ”

            As far as i am aware this statement is false. If you are referring to the sleep study mentioned above, the results did not show any increase in cortisol levels on the nights they were sleep training compared to the nights they were not. This study is also badly designed because it does not have a control group and it only uses 25 tests subjects, too few to draw any significant conclusions.

            ” Elevated cortisol levels have been shown to cause harm to other young animals. ”

            This statement is also not accurate. Consistent elevated cortisol levels from chronic stress over a long period of time does indeed show a negative effect on the brain. This has been shown in rats and mice, as i mentioned before, who had undergone electric shocks to educe a stress response.This has nothing to do with sleep training. It’s not the same thing as letting your child cry for a couple of nights within a loving home environment. The people making this coloration already have already made up their mind that sleep training is harmful and they are then looking for studies to support their claim. These studies do not have any relevance to sleep training.

            Your evidence is week. On the contrary, the evidence supporting sleep training, which is much more extensive, shows time and again no negative effects on the infant.

        • Fiona says:

          No, i said there has not been a skyrocketing increase in autism, ADHD etc. What i said is that doctors are better at diagnosing people today than they were before. There is an increase in diagnosis, not an increase in rates.

        • Melissa says:

          Terri, that’s an interestng theory you have about babies needing a still, quiet, dark environment to get REM sleep. I don’t suppose you have any evidence to back it up, but I’m asking anyway just for the heck of it. One of the interestng thngs about this theory is that it goes against just about all the evidence we have about how babies sleep. Have you ever heard of a cradle? It’s a device that helps babies sleep by rockn them. People have been using them for thousands of years because they figured out that babies sleep much better when moving.

  9. susan feldmiller says:

    WOW, NO evidence? You can not be serious. NONE at all? Have you even read one book on infant development? Object permanence? There is a reason crying releases cortisol in the baby and the parent. A reason this subject is controversial. It is unbelievable than anyone would say there is no evidence in the contrary. I am a grandmother and have been a lactation consultant for 20 years. You are extremely confused.

    • Terri Mulhern says:

      Susan I have read thousands of them. I have also taken 50-100 hours of specialized education in the areas of child development and care for over 25 years. I am working on a Master’s in Social Work and a Master’s in education. More importantly I spend every day parenting for a living! I would counsel you that anyone can write a book or have a theory, but if you only look to experts who have the experience and practice to back it up you will find that CIO gets better long-term results. The reason is simple. If you keep your child from crying from day one, at what point do you begin to let them cry? The problem is that children have to learn to interpret and react to negative input at sometime in their life, and they have to learn to comfort themselves and become well-adjusted. They cannot do this if there is no opportunity to. And children need rest more than anything. You try sleeping in a huge swing with music playing in your ear, in a seated position with your head rolling forward, with a belt around your waist. Or try sleeping in a sling hanging around a moving object who is talking, coughing, bending etc.. I know you cannot replicate what these parents are doing to their babies but I also know if you could there is no way you would achieve 10 hours a night of restful sleep with REM sleep included. We have to stop raising a nation of overstimulated children with no negatives and no boundaries. Sleep training is teaching your baby how to calm down and rest. It is not hateful, it does not have to be guilt inducing. We are here to teach our children how to eat, sleep, go to the bathroom, play nice to others etc… We are not put on this earth to make sure they never have a moment of stress, we are here to teach them how to handle it for themselves.

  10. Melissa says:

    Here’s an overview of studies examining the SAFETY, not just the efficacy, of sleep-training:

  11. Melissa says:

    Where is the evidence for your statements, Fiona? You make statements like, “All babies cry, a lot.” It’s true that most babies in the US, raised in accordance with typical American customs, cry a lot. Look at studies of crying babies in other cultures, however, and you see that this American pattern of crying is an artifact of American conditions, not something inherent in babies.

    Where is the evidence for you statement that, “The stress of normal [sic] crying for a baby is not equal to the kind of high stress an adult may go through which can have negative effects on the persons health”? If you have found evidence that babies are immune to stress-related health problems, which are known to be so harmful to adults, I would very much like to see this evidence. Isn’t this supposed to be an evidence-based blog?

  12. Fiona says:

    @ Melissa

    The stress of normal crying for a baby is not equal to the kind of high stress an adult may go through which can have negative effects on the persons health. All babies cry, a lot. Crying is how they communicate that they need something. If crying caused brain damage than all babies would suffer because all babies cry. A lot of babies have colic, for example, my two had it really bad and would scream all evening even though i was holding them and comforting them. Crying is normal and there is no evidence to suggest it is damaging in any way to their development. Stress caused by abuse and neglect can of course cause problems, but a baby who cries a lot within a loving home environment is not going to be psychologically damaged because of sleep training.

    • susan feldmiller says:

      Such a HUGE difference between crying WITH a parent comforting them and crying alone in a dark room. Unbelievable that you do not get this difference.

  13. Melissa says:

    Your “comprehensive systematic review” looks only at efficacy, not safely. What if studies of a drug showed evidence of efficacy, but did not study safety? What if some studies suggested harm, but didn’t have proper controls? Would you give that drug to a baby before its safety had been firmly established?

    The link between stress and health problems in adults is so firmly established, I would want to see very strong evidence proving that babies are somehow immune to these stress-related problems before subjecting them to something that they obviously find so stressful.

    • Shyanne says:

      Look guys, whatever it is that you believe in and whatever research and evidence you find that satisfactorily supports or denies your beliefs is well and good for you.
      We’re clearly not looking to change each others minds and convert all pro/anti-CIO parents the other way. All the information that is gathered and is presented is out there for you to form your own opinions. Mummy shaming someone just because they are doing things a way that you do not believe in is not going to do anybody any good. At the end of the day, each of us is doing the best that we can with what we know and what we believe.

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