Is Sleep Training Helpful or Harmful?

If you’ve ever googled “sleep training,” you’ve probably landed somewhere between panic and promise. One post says it’s traumatic. Another says it saved their sanity. Meanwhile, you’re just trying to help your baby (and yourself) get some rest.

Here’s the truth: sleep training isn’t one-size-fits-all. And it’s not just “cry it out.” But in reality, it’s a broad umbrella of strategies designed to help babies learn to fall asleep independently and resettle during the night. But parents often wonder: How safe are these methods? What do they actually mean for a baby’s stress levels, development, or long-term attachment?

So, how can parents make sense of all the available information out there–and make a decision that feels right for their child and their family?

Heads up–this is a deep dive! If you’re in the thick of sleep challenges or just want clarity on what’s safe, effective, and realistic, this newsletter includes the most relevant research to guide you. Save this one. Revisit it. Share it with a friend.

What Do We Mean by Sleep Training?

When people hear “sleep training,” they often picture one thing: closing the door and letting a baby cry alone. But that image doesn’t reflect the range of tools available–or the way most families actually approach it.

Sleep training isn’t a single method. It’s a group of behavioral strategies that aim to support independent sleep–gradually, gently, or with more structure, depending on what works for your baby. These approaches vary in how much parental involvement they include, and not every one involves tears. 

And my established definition of “independent sleep” means a child  being able to go down to sleep with minimal assistance (rocking and cuddling is fine!) and be able to connect sleep cycles without assistance. 

Remember: we all wake up briefly during the night to shift or adjust. But if a baby or toddler has strong sleep associations—like needing to be fed, rocked, or held to fall asleep—they often can’t resettle on their own when they naturally wake between cycles.

Here are the most common types

Sleep training doesn’t have to be harsh, rigid, or all-or-nothing. Think of it less like boot camp and more like sleep coaching–some days you're the cheerleader, other days you're the referee. And sometimes, you're just the exhausted parent in pajamas doing their best.

Choosing whether–or how–to support independent sleep is a personal decision, and there’s no one-size-fits-all approach. What matters most is that your choice aligns with your child’s needs, your parenting values, and your family’s well-being.

That said, it’s also important to separate fact from fiction when weighing your options. This newsletter will dive into that–clearing up common misconceptions and helping you make informed decisions, whether you choose formal sleep training or not.

Some families blend strategies. Others decide not to sleep train at all and let their child gradually develop independent sleep on their own–and that’s okay too. The goal isn’t perfection–it’s finding what works for your child and your family.

In my experience, many children do begin to learn independent sleep with time and support. However, I often see persistent sleep struggles related to strong sleep associations–especially after 18 months. That’s why I’m a proponent of some degree of sleep teaching by 18 months–not just for the child’s sleep health, but for the well-being of the entire family.

Signs it might be time to gently support independent sleep: If after a period of allowing baby to do it on their own:

• Your baby needs the exact same input (feeding, rocking) every time they wake

• You or your partner are feeling exhausted, resentful, or anxious

• Sleep disruptions are affecting bonding, routines, or mental health

Does Sleep Training Work?

One of the biggest questions parents have about sleep training is whether it actually works. Not just in theory–but in real life, with real babies.

It makes sense to want a clear answer. After all, if you're going to try a strategy that involves disrupted nights or emotional moments, you want to know it’s worth it. Thankfully, this is one area where the research is consistent: sleep training can improve sleep for both babies and parents.

We have multiple high-quality studies—and even long-term follow-ups—that show real improvements in how long babies sleep, how easily they fall asleep, and how rested and confident parents feel.

One of the strongest studies we have on sleep training is a 2016 randomized controlled trial by Gradisar and colleagues. The study followed 43 babies aged 6–16 months. Families used either graduated extinction, bedtime fading, or received sleep education only. Researchers tracked sleep patterns, stress markers, and attachment outcomes over a 12-month period. Researchers used a mix of sleep diaries, actigraphy (movement-based sleep trackers), salivary cortisol (a stress hormone), and parent questionnaires.

Here’s what they found:

• Babies fell asleep faster in both intervention groups.

• Graduated extinction reduced night wakings and nighttime restlessness.

• Cortisol levels (a stress marker) slightly declined.

• Parents reported lower stress during the first month (turns out, getting more than two hours of sleep in a row really is magic. Who knew?).

• No differences in emotional or behavioral development.

• Attachment security was the same across all groups.

Like all research, this study had limits–it was small and only followed families for a year. But it’s still an important piece of evidence that both bedtime fading and graduated extinction can improve sleep without harming stress levels or the parent-child bond.

Another randomized controlled trial published in 2015, explored whether a brief behavioral sleep intervention could make a meaningful difference for families. It included infants aged 6-8 months and compared families who received sleep education and support with those who received general safety guidance.

Here’s what they found:

• Night wakings didn’t change much based on sleep trackers.

• Only 4% of intervention parents rated their baby’s sleep as a serious problem (vs. 14% in the control group). 

• Parents in the sleep training group reported improvements in: depression symptoms, fatigue, sleep quality, and confidence in managing sleep and setting limits.

This study reminds us that success isn’t always measured by how many times a baby wakes up–it’s also about how supported, rested, and capable parents feel. Even if night wakings continued, families felt better equipped to handle them. And that can be just as meaningful as a longer stretch of sleep.

To zoom out a bit, a 2022 meta-analysis looked at 10 randomized controlled trials on behavioral sleep interventions (BSIs) for children under 3 years old. These interventions included methods like self-soothing strategies, extinction techniques, and consistent bedtime routines. The researchers focused on both infant sleep and maternal well-being.

Here’s what they found:

• Parents were about 50% less likely to report sleep problems in the intervention group.

• Moms in the intervention group slept better overall.

• Night wakings didn’t change much between the intervention and control groups.

• Maternal depression scores didn’t improve, but sleep quality did.

So, what does this mean for families? Behavioral sleep strategies may not eliminate every night waking, but they can still lead to meaningful changes–especially in how parents experience and manage sleep. While they may not eliminate all night wakings, they can reduce sleep struggles overall. More research is still needed to better understand how age, temperament, and intervention type influence outcomes.

Is Sleep Training Safe? What About Stress, Attachment, and Long-Term Impact?

When sleep training comes up, many parents aren’t just thinking about whether it works–they’re wondering what it means for their baby’s stress, emotional development, and long-term wellbeing. Is it safe to let them cry? Could it impact bonding or brain development?

These are valid questions. And thankfully, they’re not new–researchers have been studying the emotional and physiological impact of sleep training for years. While no method is right for every baby, the evidence so far is largely reassuring.

In one of the most widely cited long-term studies, researchers followed families five years after using behavioral sleep training methods like graduated extinction. The goal? To see if there were any lasting effects on children’s emotional development, behavior, or attachment.

Here’s what they found:

• No differences in children’s emotional or behavioral health.

• Similar sleep habits and rates of sleep problems between groups.

• No differences in parent-child attachment, closeness, or conflict.

• No changes in maternal depression, anxiety, or parenting style.

• Overall, no evidence of lasting harm–or lasting benefit.

This study provides strong reassurance that sleep training doesn’t harm children’s development or the parent-child relationship in the long term. One limitation? About 30% of families didn’t complete the follow-up, which could influence results. Still, this remains one of the most rigorous long-term studies we have–and it supports the safety of behavioral sleep interventions well beyond infancy.

TLDR? No lasting harm, no lifelong trauma–just some families sleeping better and some babies learning the fine art of falling asleep solo.

Another important part of the safety conversation is how sleep training affects parents–especially during a time when mental health and exhaustion often go hand in hand. One study looked at whether brief, nurse-led sleep support during routine well-child visits could improve both infant sleep and maternal well-being.

The intervention included behavioral strategies–like controlled comforting and camping out–delivered through personalized sleep plans, educational materials, and follow-up for families with 7-month-olds.

Here’s what they found:

• Fewer mothers reported sleep problems at 10 and 12 months in the intervention group.

• Mothers had lower depression scores and reported better sleep quality.

• The intervention also reduced healthcare costs and was widely seen as helpful and easy to follow.

• Most parents continued using the strategies and felt supported by their partners.

While all outcomes were self-reported and follow-up ended at 12 months, this study offers strong short-term evidence that behavioral sleep training can improve both baby sleep and parent well-being, without adding burden or cost to families.

While most long-term studies offer strong reassurance, there’s one smaller study that often comes up in critiques of extinction-based methods. It doesn’t show lasting harm, but it does raise thoughtful questions about what babies experience physiologically during the early stages of sleep training.

This short-term study followed 25 mother-infant pairs during a five-day inpatient extinction program. Researchers measured cortisol (a stress hormone) before and after the sleep routine on days one and three.

Here’s what they found:

• On day one, babies cried and had high cortisol–and so did their mothers.

• By day three, babies stopped crying–but cortisol remained elevated.
  Mothers’ cortisol dropped, suggesting a disconnect between the baby’s internal stress and what the parent perceived.

• Researchers called this a temporary “loss of synchrony” between baby and caregiver.

This study often raises concerns because it shows that crying can stop before internal stress resolves. But it’s important to interpret it within its limits: it involved a small sample, a short timeframe, and no long-term follow-up. It doesn’t tell us whether babies adapt physiologically over time–or whether this early stress mismatch has any lasting impact.

What About Study Limitations?

By now, you’ve seen that we have a solid body of research on behavioral sleep training. But like any area of science–especially one that involves babies, parenting, and home life–every study has its limitations.

Many rely on parent-reported data–which means the results may depend on whether mom had one coffee or five before filling out the survey. Others use small sample sizes or lack long-term follow-up. Some use cortisol as a marker for stress, which gives us useful but incomplete insight into how a baby is actually coping.

And then there are the things that no study can fully account for: a child’s temperament, a parent’s mental load, genetics, family routines, cultural norms, or the presence of other siblings. Sleep is deeply personal, and no two children–or families–are the same.

So, will we ever have a perfect sleep training study? Probably not.

Because sleep–just like parenting–is multifactorial. It’s shaped by feeding, temperament, parental mental health, cultural norms, daytime connection, routines, and more. You can’t fully isolate sleep training from the rest of a baby’s environment–and maybe that’s the point.

What the research can offer is a strong foundation, not a script. It gives us clues, trends, and reassurance. And from there, it’s up to each family to make the decision that feels right for them.

How I approached sleep training with my children

After residency, I worked at a pediatric practice in NYC known for recommending sleep training as early as 2 months. At first, I was surprised–most guidelines suggest starting around 4 months. But then I saw something interesting: it was working. Babies were stretching their nighttime feeds, and many families were avoiding the dreaded four-month sleep regression altogether.

Now, this timing is still considered controversial, and I only recommend it if a baby is developmentally ready and already stretching nighttime feedings by then (Hello Newborn Sleep Workshop on how you can do this). 

With our son Ryaan, we used the full extinction method at around 2.5 months. Yes, there were tears–and I talk more about the details and our thought process in this podcast episode. But it worked well for him. To this day, Ryaan is an excellent sleeper, not just because of that initial training, but because of how we also supported him through regressions and nap refusals as he got older.

When our daughter came along, I took a more individualized approach. My husband asked, “Are we going to sleep train her too?” I told him we’d have to see–because temperament matters. She was much more of a contact sleeper, needed more physical closeness, and responded differently than Ryaan. We didn’t end up needing formal sleep training because I followed the same principles from the Newborn Sleep Workshop, and she was sleeping 11 hours by 12 weeks.

Of course, like most babies, she still went through regressions. During those times, we used a modified Ferber approach, adjusting the timing and check-ins as she grew.

That’s the beauty of understanding different strategies: you can adapt as your child grows and their needs evolve. Maybe you start with full extinction and later shift to Ferber. Or maybe, like we did with Ryaan during toddler regressions, you lay next to them until a timer goes off. Flexibility is key.

Final Thoughts

There’s no one “right” way to approach sleep–and there’s no gold star for choosing a particular method. Some families choose the full extinction method and see quick, lasting results. Others go slowly, responding more during regressions or teething. Some wait it out entirely, and that works for them, too.

Even with a plan, sleep can still be unpredictable. Sleep plans are like roadmaps with detours: helpful, but babies will still find their own route. Sometimes that route includes 2 a.m. dance parties. Babies go through leaps, illnesses, growth spurts–and sometimes they just need more help. Sleep training doesn’t guarantee smooth nights forever. It’s a strategy some families use to support more restful sleep, not a measure of parenting success.

What matters most is that you feel supported. That your baby feels safe and loved. That you’re making choices not from fear or pressure–but from clarity and confidence.

As a pediatrician and a parent, I believe sleep training is worth considering–because I’ve seen how it helps families, both in my clinical practice and with my children. I used full extinction with my son at 2 months, and later took a more gradual approach with my daughter during developmental leaps. Both remained securely attached, well-rested, and thriving.

Sleep training isn’t about whether your baby cries or doesn’t cry. It’s about helping them learn a new skill–with plenty of love, connection, and responsiveness in the mix. Whether you’re team extinction, team gradual, or team “let’s just survive tonight”–you’re doing great. You’re showing up, learning, and leading with love. And that’s what truly matters.

You’re not doing this wrong. You’re not behind. And you’re not alone.

On The Podcast

You’ve probably heard the claim that sleep training—especially methods like “cry-it-out”—can flood babies with toxic stress. But is that actually what the science says? In this episode, I sit down with a leading developmental expert to unpack the research on cortisol, stress, and infant development. We cover how the stress response system works, what truly qualifies as toxic stress, and why common fears about sleep training may be missing important context. Whether you’re team sleep-train or not, this episode offers clarity, compassion, and evidence-backed guidance.

Key Takeaways:

• Cortisol is a normal, necessary hormone that helps us respond to stress.

• Not all stress is toxic—especially when it’s brief and supported by a caregiver.

• There’s no evidence linking sleep training with long-term harm.

• Misinterpreting small or flawed studies can create unnecessary fear for parents.

• Sleep training, when developmentally appropriate, can be a positive and adaptive experience for both babies and parents.

Are you still hearing that you should wait days between introducing new foods—or that food causes eczema? Are you stressed about feeding your baby the top 9 allergens?

In this episode, I sit down with pediatric allergist Dr. Dave Stukus to bust the biggest myths about food allergies. We’re talking real science, not fear: when to introduce allergens, why elimination diets can do more harm than good, and what’s actually driving the rise in allergies today. 

We discuss: 

• Early allergen introduction helps prevent food allergies.

• Food doesn’t cause eczema—here’s what actually does.

• Vaccines don’t cause allergies—here’s what’s behind the rise.

On YouTube

Learn 8 key facts every parent should know about food allergies in babies—risks, signs, prevention, and what actually helps. The video covers:

• What’s the difference between food allergies and a food intolerance?

• Are food allergies on the rise?

• Who is the most at risk for food allergies?

• Does early introduction prevent food allergies?

• What do food allergy reactions look like?

• What to do if my child has an allergic reaction to a food?

• Should I get my child tested for allergies before starting solids?

• Can food allergies be outgrown?

Ask Dr. Mona

An opportunity for YOU to ask Dr. Mona your parenting questions!

Dr. Mona will answer these questions in a future Sunday Morning Q&A email. Chances are if you have a parenting concern or question, another parent can relate. So let's figure this out together!