Written by: Jenn Schoen, Certified Pediatric Sleep Consultant
Sleep training is one of the most debated topics in early parenting. While many families find it transformative, others worry it might cause stress, harm emotional development, or damage attachment. These fears are understandable—nurturing a baby’s emotional well-being is every parent’s top priority.
The good news: decades of high-quality research consistently show that sleep training is safe, developmentally appropriate, and not harmful to a baby’s emotional or psychological health. In fact, when done thoughtfully, sleep training often supports healthier sleep, stronger emotional regulation, and more positive parent-child interactions.
This guide breaks down what science really tells us about sleep training, how it affects babies, and why it’s a tool you can use confidently if it aligns with your family’s needs.
What Is Sleep Training—and What Isn’t It?
Sleep training is the process of helping a baby learn independent sleep skills: falling asleep on their own at bedtime and resettling after normal night wakings. It does not mean ignoring your baby, withholding comfort, or forcing them to sleep through hunger.
There are many approaches to sleep training—including gentle, gradual, and intermediate methods—that allow parents to stay responsive while teaching new skills. The goal is consistency and predictability, not abandonment.
Is Sleep Training Harmful? The Evidence Says No.
Concerns about attachment, emotional well-being, and long-term effects are among the most common questions parents ask about sleep training—and they are valid questions. Fortunately, decades of high-quality, peer-reviewed research consistently show that sleep training is safe, developmentally appropriate, and does not harm a baby’s emotional health, stress regulation, or relationship with caregivers.
The Strongest Evidence: Long-Term Outcomes
The most comprehensive research to date is a five-year longitudinal study by Price et al. (2012). This study followed families who used behavioral sleep interventions and compared them to families who did not.
After five years, researchers found:
- No increase in emotional or behavioral problems
- No differences in attachment security—meaning the bond between parent and child remained strong
- No harm to parent-child relationships
- No long-term stress patterns or cortisol abnormalities
In simpler terms: babies who were sleep trained were just as emotionally healthy, securely attached, and well-adjusted as babies who were not sleep trained—even years later.
Additional Research Confirms Sleep Training Is Safe
Sleep training has been one of the most studied parenting interventions in infant sleep science. Across dozens of studies, results remain consistent:
- Mindell et al. (2006). A meta-analysis of 52 studies found that behavioral sleep interventions reliably improve sleep without harming attachment or development.
- Hiscock et al. (2007). Families who used behavioral sleep training saw a reduction in infant sleep problems and a significant decrease in maternal depression, showing benefits for both parent and child.
- Gradisar et al. (2016). When researchers measured stress, cortisol levels, and emotional outcomes in babies undergoing sleep training, they found no evidence of long-term harm and no disruptions to emotional regulation.
- Paulus et al. (2019). Follow-up research showed that infants who developed independent sleep skills actually demonstrated better emotion regulation over time.
Across all of these studies, one message is clear: sleep training does not harm infants—and often supports healthier routines and emotional stability.
Understanding Crying During Sleep Training
For many parents, the hardest part of sleep training is the crying. It’s important to understand what this crying represents.
- Crying during sleep training is a protest to change, not a signal of trauma or fear.
- Babies cry because something familiar—like rocking or feeding to sleep—is no longer happening, and they are adjusting to new expectations.
- Crying during sleep training does not mean your baby feels abandoned or unsafe.
What protects attachment is not the absence of crying—it’s the presence of consistent, loving, responsive caregiving throughout the day, which sleep training does not change. Snuggles, holding, playtime connection, eye contact, and attentive feeding continue to build secure attachment even while nighttime routines shift.
The Takeaway
Sleep training does not cause emotional harm, attachment issues, or long-term stress. Babies who are sleep trained are just as bonded, loved, and emotionally healthy as those who are not. And in many families, sleep training actually improves emotional well-being by supporting better sleep, more predictable routines, and more regulated parents.
Sleep training is not only safe—it can be transformative for the entire household.
Why Sleep Training Can Actually Support Emotional Health
Parents often worry that sleep training may cause emotional stress, but research shows the opposite: well-rested babies are better able to regulate emotions, handle transitions, and engage with the world around them. Sleep is a biological foundation for emotional well-being, and when babies get consolidated, high-quality sleep, their brains function in a far more regulated, resilient state.
How Better Sleep Supports Babies’ Emotional Development
Consolidated sleep is linked with:
- Stronger coping skills: Babies who sleep well have a more stable stress response system and recover from frustration more quickly.
- More stable moods: Adequate sleep reduces irritability and supports steadier emotional expression throughout the day.
- Better attention and learning: Research shows that sleep improves memory consolidation and supports the neural pathways involved in early learning.
- Reduced fussiness and overtired meltdowns: When babies aren’t fighting a biological sleep debt, they’re more adaptable, social, and calm.
Studies have shown that infant sleep quality plays a significant role in temperament, emotional reactivity, and self-soothing abilities. In other words, better sleep helps babies feel more regulated, not less connected.
Sleep Training Supports Restorative, Developmentally Crucial Sleep
Sleep training doesn’t “teach a baby to sleep”—it teaches them how to fall asleep independently so they can access the restorative sleep their bodies already crave. Once babies can fall asleep and return to sleep on their own, they experience:
- More deep sleep
- More time in REM (important for processing emotions)
- More predictable nap cycles
- Less overnight stress
These improvements directly support healthier emotional and behavioral development.
Why Parental Sleep Matters Just as Much
Sleep training benefits parents, too—and this has a powerful ripple effect on emotional connection.
When parents get more sleep, they experience:
- More patience and emotional bandwidth
- More positive, attuned interactions with their baby
- Lower irritability and stress
- Improved ability to read and respond to their baby’s cues
- Greater consistency in caregiving, which strengthens attachment
A well-rested parent is more present, more responsive, and more capable of providing the sensitive caregiving that drives secure attachment.
Better Sleep Can Strengthen the Parent-Child Bond
Many families report that once sleep stabilizes:
- Bedtimes feel calmer
- Days feel more enjoyable
- Parents feel more connected and less overwhelmed
- Babies are happier, more engaged, and easier to comfort
Far from weakening emotional connection, improved sleep often creates the conditions for deeper, healthier bonding because both baby and parent are better regulated, more rested, and more emotionally available.
In short, high-quality sleep supports emotional health—and sleep training is often the bridge that helps families get there.
When Sleep Training Should Not Be Used
While sleep training is safe and effective for most babies, there are moments when it’s not the right time to start—or when you should temporarily pause your plan. Sleep training requires consistency, predictable routines, and a baby who feels physically comfortable enough to learn new skills. When those conditions aren’t in place, the process can feel harder, take longer, or become emotionally stressful for both parents and baby.
Here are the key situations when sleep training should wait:
Do NOT Sleep Train During Illness or Fever
If your baby is sick—with a fever, cold, virus, stomach bug, or respiratory symptoms—they need comfort, hydration, and rest more than they need independent sleep training. Illness disrupts sleep temporarily, and babies often require more soothing than usual. Trying to sleep train during this time can lead to increased distress and slower recovery.
Do NOT Sleep Train During Acute Discomfort (e.g., Teething Pain, Eczema Flare, Reflux Flare-up)
Pain or irritation makes settling and staying asleep much harder. Babies experiencing teething discomfort, intense eczema itching, reflux symptoms, or other sources of physical discomfort cannot focus on learning new sleep skills. These situations often result in increased crying or restless sleep, which can be mistaken for sleep training “not working.”
Do NOT Sleep Train When Medical Concerns are Present and Not Yet Evaluated
If your baby has symptoms such as extreme fussiness, poor feeding, abnormal breathing, growth concerns, or persistent discomfort, it’s important to consult a pediatric provider before beginning or continuing sleep training. Addressing the root cause typically leads to much easier and more successful sleep learning afterward.
Do NOT Sleep Train Before 4 Months of Age
Babies before 4 months of age are not developmentally ready for formal sleep training. Their sleep cycles are immature, feeding needs are still stabilizing, and circadian rhythms are just beginning to develop. During this stage, the focus should be on gentle habit-building, including predictable routines, safe sleep environments, and brief practice with putting the baby down drowsy but awake.
Do NOT Sleep Train During Major Transitions or Disruptions
Although not always a full “pause,” sleep training can be more challenging when:
- You’ve just returned from travel
- Your baby has started daycare
- You’ve recently moved
- A new caregiver has been introduced
These transitions can temporarily increase clinginess and sleep disruption. A few days of adjustment often help before restarting or initiating training.
Why Pausing Matters
Trying to sleep train when your baby is uncomfortable or dysregulated can lead to more crying, more frustration, and slower progress. When your baby is healthy and feeling well, they’re far more capable of learning—and much more likely to respond quickly and successfully.
What To Do Instead
Offer comfort, follow your baby’s cues, and prioritize rest. Once your baby is healthy and regulated again, you can resume your sleep training plan—and most babies pick up right where they left off.
In these situations, comfort always comes first. Sleep training can wait until your baby is ready to learn in a calm, supported, and well-regulated state.
Different Sleep Training Methods, Same Safety
One of the biggest misconceptions about sleep training is that it refers to a single, rigid method—usually “cry it out.” In reality, sleep training is an umbrella term that includes a wide spectrum of approaches.
Families can choose a method that fits their comfort level, their baby’s temperament, and their goals. Importantly, research shows that all evidence-based sleep training methods are safe when used appropriately and do not harm attachment or emotional development.
Gentle Sleep Training Methods
Gentle sleep training methods prioritize high parental presence and slow, supportive transitions.
- Parents stay close—often sitting by the crib or offering touch, voice, or brief pick-ups.
- Crying is minimized because changes happen in small steps over several days or weeks.
- Parents gradually reduce their level of involvement as their baby gains confidence falling asleep independently.
- Methods include techniques like the Shush/Pat, Pick-Up/Put-Down, and gradual elimination of sleep props.
Gentle methods are best for babies under 6 months of age, families who prefer minimal crying, and families who have a baby who responds better to slow change.
Intermediate Sleep Training Methods
Intermediate sleep training methods find a balance between comfort and independence.
- Parents use timed check-ins or brief intervals away from the crib while the baby practices self-settling.
- Crying may occur, but parents remain emotionally available and responsive throughout the process.
- Many families see meaningful improvement in 3–5 nights, making this a popular middle-ground option.
- Methods include techniques like the Camping Out and Quick Checks methods.
These methods are best for parents who want quicker results but still prefer active, ongoing reassurance.
Firm Sleep Training Methods
Firm sleep training methods are the most independent methods—and also the fastests.
- Parents place the baby in the crib awake and return at extending intervals while baby falls asleep or not at all.
- Crying is expected, but typically decreases quickly as the baby adapts.
- Many babies respond within 1–3 nights, with rapid consolidation of sleep.
- Methods include techniques like the Ferber and Cry It Out (CIO) methods.
Firm sleep training methods are best for families with babies at least 6+ months and with parents that don’t mind leaving their child to cry for longer periods and are seeking the fastest training methods.
FAQ: Is Sleep Training Harmful?
Questions about the safety and emotional impact of sleep training are some of the most common—and most important—questions parents ask. With so much conflicting information online, it’s natural to wonder whether sleep training could stress your baby, harm attachment, or affect long-term development. This FAQ section breaks down the concerns we hear most often and offers clear, research-backed answers to help you make confident, informed decisions that feel right for your family.
Does Sleep Training Damage Attachment?
No. Long-term research shows no differences in attachment security between sleep-trained and non–sleep-trained children.
Is Crying Harmful to My Baby?
Crying during sleep training is most often a sign of frustration at a change in routine—not emotional distress or trauma. Parents remain responsive throughout the day, which maintains healthy attachment.
Can Sleep Training Impact Emotional Development?
No. Research shows that independent sleep is associated with better emotional regulation and fewer sleep-related behavior problems.
Is Sleep Training Necessary for Every Family?
No. It’s a tool—not a requirement. If your baby sleeps well with your current routines, you don’t need to change anything.
Is Sleep Training Harmful for Sensitive or High-Needs Babies?
Sensitive babies may benefit from gentler, slower approaches, but sleep training itself is still safe when customized to their temperament.
Want Expert Support With Sleep Training? Poppins Can Help
If you're unsure where to start—or if you’ve tried sleep training and felt overwhelmed—you don’t have to navigate it alone. Poppins offers:
- Personalized sleep plans from pediatric sleep experts
- Real-time coaching for tough nights
- 24/7 access to medical and developmental guidance
- Supportive methods aligned with your parenting style
Whether you're exploring gentle approaches or need step-by-step guidance, we’ll help your whole family rest better. Check out our sleep training packages here.
