If you're considering sleep training, you've probably encountered frightening claims: that it causes psychological damage, harms the parent-child bond, or leads to emotional problems later in life. These fears cause many exhausted parents to suffer through months or years of sleep deprivation, believing they're protecting their child. But what does the actual research say? A rigorous five-year follow-up study provides the clearest evidence yet that sleep training causes no emotional harm.
The Landmark Five-Year Study
In 2012, researchers from the Royal Children's Hospital in Melbourne, Australia published a groundbreaking study in Pediatrics, the official journal of the American Academy of Pediatrics. This study followed 326 children who had parent-reported sleep problems at 7 months of age, tracking them until age 6 to determine if behavioral sleep interventions caused any long-term harm.[1]
The study was a follow-up to a randomized controlled trial—the gold standard of scientific research. In the original trial, families were randomly assigned to either receive behavioral sleep training (the intervention group) or standard care (the control group). The behavioral techniques were delivered over 1 to 3 individual nurse consultations when infants were 8 to 10 months old.
Study Design and Methodology
The researchers measured a comprehensive range of outcomes at the five-year follow-up:
- Child outcomes: Mental health, sleep quality, psychosocial functioning, and stress regulation (including cortisol levels)
- Child-parent relationship: Closeness, conflict, global relationship quality, and attachment patterns
- Maternal outcomes: Mental health (depression, anxiety, stress) and parenting styles
Of the original 326 families, 225 (69%) participated in the follow-up study—a remarkably high retention rate that strengthens the validity of the findings.
The Results: No Evidence of Harm
The study's findings were unequivocal: there was no evidence of differences between intervention and control families for any outcome.[1] Let's examine the specific findings:
Child Mental Health
Children who were sleep trained as infants showed no differences in emotional behavior scores (P = 0.8) or conduct behavior scores (P = 0.6) compared to children who weren't sleep trained. Both groups had similar rates of sleep problems at age 6 (9% vs 7%, P = 0.2) and comparable sleep habits scores (P = 0.4).
Stress Regulation
One of the most important findings relates to cortisol, the stress hormone. Critics of sleep training often claim that allowing babies to cry elevates cortisol levels, potentially causing brain damage. However, this study found no difference in chronic stress levels between groups (29% vs 22%, P = 0.4). This directly refutes the claim that sleep training causes emotional harm through stress-related mechanisms.
Parent-Child Relationship
Perhaps the most reassuring findings relate to the parent-child bond. The study found:
- No difference in child-parent closeness (P = 0.1)
- No difference in parent-child conflict (P = 0.4)
- No difference in global relationship quality (P = 0.9)
- No difference in attachment patterns, including disinhibited attachment (P = 0.3)
Both parent-reported and child-reported psychosocial functioning showed no differences between groups (P = 0.7 and P = 0.8, respectively).
Maternal Outcomes
Mothers in both groups showed similar levels of depression, anxiety, and stress (P = 0.9), and similar rates of authoritative parenting (63% vs 59%, P = 0.5).
What the Researchers Concluded
The study's conclusion is clear and directly applicable to the concerns many parents have: "Behavioral sleep techniques have no marked long-lasting effects (positive or negative). Parents and health professionals can confidently use these techniques to reduce the short- to medium-term burden of infant sleep problems and maternal depression."[1]
This conclusion provides strong evidence that the fears surrounding sleep training are not supported by scientific research.
Addressing Common Concerns
The Cortisol Argument
Critics of sleep training often cite studies showing that crying increases cortisol levels in infants. However, it's important to understand context. Normal, healthy babies experience elevated cortisol in many situations—during diaper changes, baths, car rides, and vaccinations. Brief elevations in cortisol are not harmful and are part of normal stress response development.
The concern about cortisol damage comes from research on children who experienced severe abuse or neglect—situations of chronic, extreme stress that bear no resemblance to a few nights of bedtime protests during sleep training. As Dr. Craig Canapari, Director of the Yale Pediatric Sleep Center, explains: "Long term persistent elevation in cortisol can be dangerous to development, but this is not going to occur with intermittent crying in otherwise healthy children who are well cared for."[2]
The Attachment Concern
The five-year study specifically measured attachment outcomes and found no differences between groups. This makes sense when we understand what attachment research actually shows. The founders of attachment theory, Mary Ainsworth and John Bowlby, emphasized that secure attachment develops from the overall quality of care a child receives, not from specific parenting techniques.
As quoted in research on attachment parenting: "Attachment theory suggests that babies thrive emotionally because of the overall quality of the care they've experienced, not because of specific techniques. A bottle-fed baby whose mother is sensitively attuned will do better than a breastfed baby whose mother is mechanical and distant."[2]
The "Cry It Out" Misunderstanding
Many concerns about sleep training assume that all approaches involve leaving babies to cry alone for extended periods. In reality, there are many evidence-based methods, including gentle approaches that involve regular parental check-ins and reassurance. The study included various behavioral techniques, not just extinction methods.
The Benefits of Addressing Sleep Problems
While the five-year study shows that sleep training causes no emotional harm, other research demonstrates clear benefits of addressing infant sleep problems:
Reduced Maternal Depression
Poor infant sleep is strongly linked to maternal depression. When babies sleep better, mothers often experience significant improvements in mood and mental health. The original trial (before the five-year follow-up) showed benefits for maternal mental health in the sleep training group.
Better Parenting
Sleep-deprived parents struggle to be patient, present, and responsive. When parents are well-rested, they're better equipped to provide the sensitive, attuned care that truly supports healthy child development.
Improved Family Functioning
Chronic sleep deprivation affects relationships, work performance, and overall family quality of life. Addressing sleep problems can improve functioning across all these domains.
Understanding the Research Limitations
No single study is perfect, and it's important to acknowledge the limitations of this research. The study notes that researchers (but not parents) were blinded to group allocation. Additionally, some families didn't complete the follow-up assessment.
However, the study's strengths—randomized design, long follow-up period, comprehensive outcome measures, and high retention rate—make it one of the most robust investigations of sleep training outcomes available.
What About the Criticism?
The study did receive some criticism, as noted in the comments section of the Pediatrics publication. Critics raised methodological concerns about treatment integrity and the control group's practices. However, the fundamental findings—no differences between groups across a comprehensive range of outcomes—remain significant.
It's worth noting that proving a negative is always challenging. The study can't definitively prove that no child has ever been harmed by sleep training. However, if sleep training caused widespread harm, we would expect to see some signal in a study of this size and quality—and no such signal appeared.
The Real Harm: Chronic Sleep Deprivation
While parents worry about potential harm from sleep training, there's strong evidence that chronic sleep deprivation causes real problems for both parents and children:
For Parents
- Increased risk of depression and anxiety
- Impaired cognitive function and decision-making
- Increased risk of accidents, including car accidents
- Relationship difficulties
- Reduced ability to provide sensitive, responsive parenting
For Children
- Developmental impacts on memory and learning
- Behavioral difficulties
- Emotional regulation challenges
- Potential long-term health impacts
Given this evidence, addressing sleep problems—using safe, evidence-based methods—may actually protect children and families from real harm.
Making an Informed Decision
Every family must make their own decisions about sleep, based on their values, circumstances, and comfort level. However, these decisions should be based on accurate information, not fear.
The five-year follow-up study provides reassurance that behavioral sleep techniques, when used appropriately, do not cause the lasting harm that many parents fear. Sleep training causes no emotional harm when done thoughtfully and with professional guidance.
How Rose Sleep Co Can Help
At Rose Sleep Co, I help families throughout Southern and Central California develop personalized sleep plans that align with their values and comfort level. As a sleep consultant certified by the Institute of Pediatric Sleep and Parenting, I use evidence-based approaches and provide support throughout the process.
If you're struggling with sleep deprivation but worried about the effects of sleep training, I'm here to answer your questions and help you find an approach that works for your family. Book a free discovery call at (213) 935-0769 or fill out our intake form.
You don't have to choose between your baby's emotional health and getting the sleep your family needs—the research shows you can have both.
References
- 1. Price, A. M. H., Wake, M., Ukoumunne, O. C., & Hiscock, H. (2012). Five-year follow-up of harms and benefits of behavioral infant sleep intervention: Randomized trial. Pediatrics, 130(4), 643-651. https://doi.org/10.1542/peds.2011-3467
- 2. Canapari, C. (2015). Sleep Training Doesn't Hurt Your Child. Yale Pediatric Sleep Center. Retrieved from https://drcraigcanapari.com/why-fixing-your-kids-sleep-problems-is-not-selfish/
