Why you shouldn’t sleep train before age 1: What science says about your baby’s sleep and brain development

If you’re a new parent, you’ve probably spent time with other new parents, at playdates, in doctors’ waiting rooms, or during those quick stroller walks, and somehow the conversation always circles back to sleep. And right after that comes the big question: “When should we start sleep training?”

The tricky part? Everyone seems to have a different answer. One parent says early is best, another swears you should wait, and family members might chime in with advice from “back in their day.” It’s no wonder you’re left wondering, So what’s actually right for my baby?

To help cut through the noise, we spoke with Debbie Gerken, RNC-NICU, a Certified Registered NICU Nurse, Certified Pediatric Gentle Sleep Coach, Postpartum Parent Educator, and founder of Sleep Like a Baby Consulting. With 30+ years of experience supporting families through newborn care, pediatric sleep, and early development, she reminded us of something reassuring: when it comes to babies under one year old, the science and developmental reality often support pausing formal sleep training.

Yes, sleep matters, but so does development.

What’s happening in your baby’s brain during the first year?

1. The first year is a time of explosive brain growth

Your baby’s brain almost doubles in size in year one, and sleep plays a central role in that growth. A 2023 study, published in Neurobiology of Sleep and Circadian Rhythms, found that longer infant sleep duration was associated with larger total brain volumes at 12 months. This rapid growth helps support:

• Neural connections
• Learning
• Emotional regulation

Debbie notes that this neurological maturation is part of why formal sleep training rarely makes sense early on.

 “The 5–6 month parameter is based on neurodevelopment and sleep science,” she explains. “At this age, a baby’s circadian rhythm is firmly in place, and they have consolidated sleep cycles.”

In other words, your baby’s brain is doing a lot of foundational building before then.

2. Babies under 1 are still developing the ability to self-soothe

Self-soothing is development, not discipline. Researchers note that infants rely heavily on caregivers to regulate stress responses and sleep-wake cycles.

Debbie expands on this beautifully: “Mature self-soothing skills are an essential part of sleep training readiness, things like bringing hands to mouth, rolling to the side, rolling to the belly, or picking up their legs and flopping them onto the mattress. These skills are rhythmic in nature, similar to rocking or bouncing from a caregiver.” 

These abilities typically strengthen between 4–6 months, but some babies may need much longer. 

What do pediatric guidelines actually say about sleep training under age 1?

Trying to understand official recommendations can feel like piecing together a puzzle: different terms, different approaches, lots of fine print. But when you zoom out, major pediatric organizations are remarkably aligned:

• Most babies under one still need nighttime feeding
• Frequent night waking is developmentally normal
• Responsiveness from caregivers supports healthy growth and emotional regulation

The AAP notes that overnight waking and feeding support healthy digestion and emotional development.
The CDC backs this up, explaining that night waking in the first year is not a “problem” but a normal part of infant sleep biology.

This is why many pediatricians recommend waiting until closer to age 1, or at least the second half of the first year, before introducing anything structured or rigid.

Why formal sleep training may not be ideal before age 1

1. Young infants aren’t developmentally ready for strict self-soothing

According to the AAP, newborns and infants still rely on caregiver regulation. Expecting them to self-soothe the way an older baby can is simply not aligned with their brain development.

Debbie puts it simply: “Formal, structured sleep training is most successful, and most respectful of a baby’s developmental stage, when we ensure the baby is truly ready, both neurologically and emotionally.”

2. Cry-based methods may interfere with neurological processes

Sleep cycles are tied to learning, memory, and brain plasticity. Disrupting these cycles too early may reduce some of those developmental benefits.

3. Attachment foundations are forming now

Responsive care during the first year supports secure attachment, which plays a significant role in emotional development.

4. Night waking is biologically normal

Waking for feeds, growth spurts, or comfort is part of typical infant development. A baby who wakes at night is not behind, in fact, they’re on track. Debbie reinforces this: “Babies do not fall behind for needing more support. Just like walking, every baby develops at their own pace.”

When sleep training can make more sense

Most pediatric sleep experts agree on a general timeline, not as a rule, but as a developmental pattern.

• 4–6 months → Gentle sleep shaping only
• 6–12 months → Structured methods may be introduced, depending on readiness
• After 12 months → Most babies can self-soothe more consistently

Debbie’s opinion aligns closely here: “Many babies are developmentally ready for formal sleep training closer to 5–6 months. But readiness varies widely. Age alone is not the determining factor.”

What parents can do before formal sleep training 

Debbie shared her favorite under-one strategies, gentle, supportive, and totally developmentally appropriate:

• Regulating daytime sleep (not too much, not too little)
• Creating a sleep environment that aligns with the baby’s temperament
• Establishing calming, predictable pre-sleep routines
• Gradually reducing tough sleep associations (like always nursing or rocking to sleep)

These steps lay the groundwork so that if and when you choose to sleep train later, it feels much easier.

If you feel pressure to sleep train “now”

Debbie has a message she tells all parents: “If the way your baby is currently sleeping is working for your baby and your family, there is no need to change anything.”

She also encourages stepping away from social media noise and well-meaning pressure from family or friends. She adds, it helps to focus on gentle tweaks, daytime activities, adjusting wake windows, optimizing sleep environments, rather than forcing skills a baby is not developmentally ready for.

When to wait on sleep training and talk to a pediatrician

According to Debbie, these signs mean: pause, don’t sleep train yet, and check with a specialist:

• Snoring
• Excessive sweating during sleep
• Fragmented or very restless sleep
• Arching or signs of discomfort
• Discomfort lying flat
• Feeding difficulties or concerns about growth
• Prematurity or medical complexities

These issues may signal underlying sleep, airway, or feeding challenges that require evaluation, not sleep training.

Conclusion

Healthy sleep is important. But so is supporting your baby’s development, feeding needs, emotional regulation, and neurological growth.

With the right timing, and the right readiness, sleep training can be effective and respectful. Before then, gentle sleep shaping and responsive care are not only okay, they’re developmentally aligned.

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Sources

1. Neural development and infant sleep patterns. PubMed. 2023. “Infant sleep development: pathways, predictors, and outcomes.”
2. Why babies don’t sleep through the night yet. HealthyChildren.org (AAP). “Sleeping Through the Night.”
3. How sleep affects early development. CDC. “Understanding Your Baby’s Sleep Patterns.”
4. How babies learn to self-soothe. HealthyChildren.org (AAP). “Self-Soothing: Helping Your Baby Learn This Life Skill.”
5. Early-life stress and infant sleep regulation. National Institutes of Health (PMC). 2016. “Sleep and Circadian Rhythms in Early Life: Health Implications.”
6. Practical sleep guidance for new parents. HealthyChildren.org (AAP). “Getting Your Baby to Sleep.”
7. Foundational neuroscience on how early life builds the brain’s wiring. National Scientific Council on the Developing Child, Center on the Developing Child at Harvard University. 2007. “The Timing and Quality of Early Experiences Combine to Shape Brain Architecture
8. Caregiver-infant co-regulation in real-life cultural contexts. Infant Behavior & Development. 2021. “Studying caregiver-infant co-regulation in dynamic, diverse cultural contexts: A call to action.”