Emily Oster recently published an article called “Why Is Everyone Afraid of Sleep Training?” The intention of the piece is pretty clear: to reassure parents that sleep training is supported by evidence, and that concerns about harm are largely unfounded and generally “fear mongering”.
While some of her points are technically accurate, the way the evidence is summarized leaves out context that many parents actually need to make informed decisions with. When that context is missing, it changes how people understand the research and how they interpret what’s happening in their own homes, often in the middle of the night, when they’re exhausted and second-guessing everything.
Before getting into the research itself, I want to take a moment to focus on the framing of the question.
“Why is everyone afraid of sleep training?”
Well, first of all, not everyone is afraid of sleep training. Our culture is one that is largely supportive of sleep training! But, beyond this observation, why parents are “afraid” of sleep training already sets a tone. It assumes fear is the driving force behind the decision, when for many parents, that simply isn’t the case. Asking why parents are “afraid” of sleep training is not a neutral question. It presumes both a problem and its cause. Fear is positioned as the explanation rather than acknowledging that many parents are making thoughtful, informed decisions. Although Emily claims neutrality by saying parents do not have to sleep train, this framing undermines that stance. A lot of parents who choose not to sleep train are informed, have read the research, understand infant development, breastfeeding physiology, temperament, and their own mental health, and are making intentional choices based on what they’re seeing in their own baby, not what they’re being told they should be seeing.
There’s also a broader cultural pattern underneath this. Women, and especially mothers, are often framed as anxious, emotional, uninformed, or easily misled when they want to respond to their babies and keep them close at night. When mothers want to do the most natural thing in the world, which is to respond to their babies and keep them close, they are often infantilized and framed as silly, uninformed, or as women who are victimizing themselves. In that kind of framing, mothers who practice responsive caregiving at night can end up being perceived as overly emotional or ignorant, even when what they’re doing is a very deliberate and biologically normal way of caring for an infant.
When decisions are framed this way, mothers begin doubting themselves and their instincts, looking to “experts” to tell them how to parent. Instead of asking whether an approach actually fits their baby, they wonder if they’re being irrational, weak, or “too attached.”
Emily’s article makes three main arguments about why parents shouldn’t worry about sleep training. I want to walk through each one and look at what the research actually shows us.
1. Sleep training increases infant sleep and reduces night wakings
Some studies do show improvements in infant sleep after sleep training interventions, that part is true. Where things start to get murkier is in how those improvements are measured, and what we’re actually counting as “better sleep.”
Across the literature, the biggest changes tend to show up in parent-reported sleep rather than in objective measures like actigraphy. Parental report captures how often babies signal and wake caregivers, and how often caregivers are noticing the wake. Actigraphy is an objective measure and captures how much babies are actually sleeping and waking. Those two types of measurement overlap, but they are not the same, and they give us different information.
Several studies find that sleep interventions have a significant impact when using parent-report as a measure, but an insignificant effect when measuring with actigraphy. Put more plainly, many babies still wake just as often, but they cry or call out less. Parents are noticing and reporting less wakes, but it doesn’t necessarily mean the baby is sleeping more.
One randomized clinical trial ((Hall et al., 2015) found no statistically significant difference in the amount of wakes sleep intervention babies had versus babies in the control group based on actigraphy data, while parents reported significantly less wakes in the intervention group. Again, babies are still waking, but parents aren’t being signaled to. This same study found that sleep trained babies slept, on average, about 16 minutes longer in their longest sleep stretch than babies in the control groups.
In another randomized trial (Santos et. al, 2019), parents reported about a 19-minute increase in nighttime sleep at six months for children who were sleep trained, but that difference disappeared when children were followed over time and objective measures were used. Actigraphy later showed more time awake without signaling in the intervention group, with no overall differences in sleep duration. The authors ultimately concluded that the intervention did not increase nighttime sleep.
Similar results have been replicated time and time again. Even when we see some improvement in duration of sleep, the results are usually very modest.
For some families, that change could feel meaningful, but it’s important to note that the data doesn’t support the idea that sleep training reliably produces large increases in infant sleep across the board. In many cases, what changes is how often babies signal, not how much they sleep.
That distinction becomes more relevant when we start thinking about infant stress and regulation because reduced signaling doesn’t necessarily mean baby is asleep or even calm. Babies can be quiet and still stressed. Parents need to have this information when decision making about how to navigate sleep.
2. Sleep training improves maternal mental health
Maternal mental health is a real concern, especially in the postpartum period when sleep is fragmented and unpredictable. There are plenty of studies showing associations between disrupted maternal sleep and postpartum depressive symptoms, as well as links between maternal-reported infant sleep problems and higher depression scores.
In the sleep training discussions, these connections are often not given the nuance and layered complexity that they deserve.
Infant sleep and maternal mental health influence each other. Infants born to mothers experiencing depressive symptoms tend to show more sleep disturbances themselves, starting very early in the postpartum period and continuing for months (Armitage et. al, 2009). So the direction of causality here isn’t simple.
It also matters what part of sleep we’re talking about. Research suggests that it isn’t simply how often a mother wakes at night that predicts mood outcomes. What seems to matter more is sleep efficiency, meaning how easily someone can fall back asleep once they’re awake (Douglas et. al, 2013). Anxiety, heightened nervous system activation, and difficulty settling again play a big role here.
Two mothers can wake the same number of times overnight and have very different mental health experiences, depending on how their bodies respond to those awakenings.
There’s also evidence that perception of sleep plays a larger role in mood disturbances than objective sleep quantity (Bei et. al, 2010). In studies that use both subjective and objective measures, distress about sleep and awareness of disruption often predict mood symptoms more strongly than total sleep time does.
This helps explain why fear-based messaging around infant sleep can make things worse without actually helping mothers get more sleep.
A systematic review by Douglas and Hill (2013) found that behavioral sleep interventions in the first six months of life do not improve outcomes for mothers or infants when broader measures of well-being are considered. A possible explanation is that limiting responsiveness doesn’t actually address the physiological drivers of maternal sleep difficulty. Things like anxiety, hypervigilance, fear around infant safety, screen use during night wakes, and difficulty calming the nervous system are all major issues that negatively impact the quantity and quality of sleep, and sleep training does not address the root cause of these specific issues. In reality, many mothers are not lacking sleep solely because of how much their baby is sleeping, but rather because they are having physiological or health issues that cause them to have difficulty sleeping, even when they have the opportunity.
Sleep is often treated as a behavioral problem with a behavioral solution, even though postpartum sleep is also shaped by physiology, nervous system regulation, and stress responses. Ignoring that piece leaves a lot of mothers feeling like they’re failing at something that may not actually be a simple behavioral problem in the first place. It’s just not as simple as sleep train your baby to get more sleep!
Breastfeeding is not a side issue
Breastfeeding sits right at the center of this conversation surrounding sleep training, yet it’s often ignored.
Multiple reviews and meta-analyses show that breastfeeding, particularly exclusive breastfeeding, is associated with a lower risk of postpartum depression (Alimi et. al, 2022). That doesn’t mean breastfeeding is protective for everyone, or that the relationship is simple, but it does mean feeding method can’t be treated as irrelevant when we talk about maternal mental health and sleep.
There’s also good evidence that stopping breastfeeding earlier than planned is associated with increased depressive symptoms, especially when that cessation is driven by pain, latch difficulties, supply concerns, or pressure from outside sources.
Many sleep training approaches involve reducing night feeding or increasing separation. Both of those can affect breastfeeding success. The Academy of Breastfeeding Medicine has explicitly noted that sleep training in infants under six months can interfere with breastfeeding because of separation and reduced nighttime feeds.
Milk production works on supply and demand, and night feeding plays a role in maintaining that balance. So for breastfeeding mothers, sleep training may improve sleep for some while simultaneously undermining a factor that supports mental health. That’s basic physiology that is often not mentioned during the sleep training discussion.
3. Sleep-trained babies show no differences in mood or development
Emily points to long-term follow-up studies showing no detected differences in child emotional or behavioral outcomes or parent-child relationships. Those studies do exist, and many parents find them reassuring, but it’s also important to be aware of their limitations.
There simply aren’t many long-term studies. Sample sizes are small, the interventions studied represent a narrow slice of what families actually do, and outcomes are often measured using parent questionnaires rather than direct observation. Many of the tools used weren’t designed to pick up on subtle relational or stress-related differences in young children.
It’s also very difficult to establish causation here. Child development is shaped by a lot of interacting factors, including temperament, parental mental health, caregiving quality, stress exposure, and social support. Sleep training can’t really be isolated as a single causal variable.
When studies report no detected harm, what they’re really telling us is that no large effects were identified within the limits of the data. That’s not the same thing as showing that harm cannot occur, only that it wasn’t detected given the study design, sample size, outcomes measured, and length of follow-up. A lack of evidence of harm shouldn’t be confused with evidence that no harm exists.
“Sleep training works better for some babies”
To her credit, Emily does acknowledge that sleep training works better for some babies than others. That makes intuitive sense because babies are all unique.
What’s missing is research that helps parents understand which babies are more likely to tolerate sleep training and which ones are not.
Most sleep training studies don’t differentiate infants by temperament, despite decades of research showing that temperament plays a major role in stress reactivity, persistence, and adaptability. Read this blog post on how temperament interacts with sleep. Some babies are more easygoing and adaptable while others are more sensitive, persistent, or intense, and will do whatever it takes to get their needs and desires met.
When those experiences are averaged together, parents of high-needs babies are often left believing that if sleep training isn’t working, they must be doing something wrong, there is something wrong with their baby, or that they need to push through harder. The research doesn’t offer much help in recognizing when a method simply isn’t a good fit for a particular baby or family. The messaging parents are often given goes something like this: “sleep training doesn’t have to involve cry it out! It can be gentle.” But, the reality is that for babies with very persistent and intense temperaments, sleep training using these “gentle” techniques will never result in an independently sleeping baby, yet parents are often left with no support or explanation to help them understand and process why sleep training just isn’t a good fit for their baby, or what they can do instead.
Responsiveness, stress, and biology
Infants rely on caregiver responsiveness to help regulate stress. Babies are designed to co-regulate with a calm, responsive caregiver. Neurodevelopmental research shows that repeated activation of stress systems without adequate co-regulation can influence how those systems develop over time.
That doesn’t mean every moment of non-responsiveness causes harm. Misattunement happens in every relationship, and repair is a normal and healthy part of development.
At the same time, sustained and purposeful non-responsiveness during periods of distress isn’t biologically neutral, and it is intellectually dishonest to ignore the abundance of research we have available to us about this topic. Responsive caregiving plays a really important role in helping infants learn how to regulate their bodies and emotions, especially early on.
The cost of overriding instinct
One thing research rarely captures well is parental distress.
For many mothers, responding to their baby’s cues is deeply intuitive. Being pressured to override that intuition can create real internal conflict and turmoil.
When parents are told that sleep training is necessary and easy, and then find it unbearable, they often turn that discomfort inward. They assume something is wrong with them, or with their baby. And they often push themselves to continue the sleep training, even when it’s not going well, and even when it’s creating stress for the entire family. This can absolutely result in poor mental health outcomes, and it shouldn’t be ignored.
Mental health is shaped by more than minutes of sleep. It’s also shaped by nervous system regulation, confidence, and whether a parent feels supported in the choices they’re making.
So, no, Emily, it’s not that we are scared of sleep training. It’s that we know our babies and have chosen to lean into our intuition that tells us to respond to them. It’s because responsiveness creates order and peace in our homes, where sleep training would feel chaotic and stressful. That choice is usually made with education, wisdom, reason, and discernment.
If you’ve ruled out infant sleep red flags, and you are wanting support shift sleep patterns that no longer work for your family, grab one of my comprehensive eCourses, such as The Infant Sleep Foundations eCourse or the Toddler Sleep Foundations eCourse. If you’d prefer 1:1 support, you can book a call or support package.
References:
Hall WA, Hutton E, Brant RF, et al. A randomized controlled trial of an intervention for infants’ behavioral sleep problems. BMC Pediatr. 2015;15:181. Published 2015 Nov 13. doi:10.1186/s12887-015-0492-7
Santos IS, Del-Ponte B, Tovo-Rodrigues L, et al. Effect of Parental Counseling on Infants’ Healthy Sleep Habits in Brazil: A Randomized Clinical Trial. JAMA Netw Open. 2019;2(12):e1918062. Published 2019 Dec 2. doi:10.1001/jamanetworkopen.2019.18062
Armitage R, Flynn H, Hoffmann R, Vazquez D, Lopez J, Marcus S. Early developmental changes in sleep in infants: the impact of maternal depression. Sleep. 2009;32(5):693-696. doi:10.1093/sleep/32.5.693
Douglas PS, Hill PS. Behavioral sleep interventions in the first six months of life do not improve outcomes for mothers or infants: a systematic review. J Dev Behav Pediatr. 2013;34(7):497-507. doi:10.1097/DBP.0b013e31829cafa6
Bei B, Milgrom J, Ericksen J, Trinder J. Subjective perception of sleep, but not its objective quality, is associated with immediate postpartum mood disturbances in healthy women. Sleep. 2010;33(4):531-538. doi:10.1093/sleep/33.4.531
Alimi R, Azmoude E, Moradi M, Zamani M. The Association of Breastfeeding with a Reduced Risk of Postpartum Depression: A Systematic Review and Meta-Analysis. Breastfeed Med. 2022;17(4):290-296. doi:10.1089/bfm.2021.0183
Huang Y, Hauck FR, Signore C, et al. Influence of Bedsharing Activity on Breastfeeding Duration Among US Mothers. JAMA Pediatr. 2013;167(11):1038–1044. doi:10.1001/jamapediatrics.2013.2632
Zimmerman D, Bartick M, Feldman-Winter L, Ball HL; Academy of Breastfeeding Medicine. ABM Clinical Protocol #37: Physiological Infant Care-Managing Nighttime Breastfeeding in Young Infants. Breastfeed Med. 2023;18(3):159-168. doi:10.1089/bfm.2023.29236.abm
