Sleep Training Is Not One Size Fits All

Infant and Toddler Development  ·  Ages 0 to 3

Sleep Training Is Not One Size Fits All

What the research actually says, what it does not say, and how to find the approach that works for your family

By Dr. Erica Buchholz, PhD  ·  Becoming Playful

Key Points

• There is no single sleep training method that the research recommends for all families.
• Multiple approaches, including both cry-it-out and gentler methods, have research support when applied consistently.
• Temperament, family values, parental wellbeing, and the child's specific developmental picture all matter.
• The method that you can apply consistently and that preserves the quality of your relationship with your child is the right method.
• Sleep deprivation affects parents' mental health, regulation, and capacity to parent. That matters too.

Everyone Has an Opinion About This

Your mother says to let them cry. Your friend says that is cruel. The internet has eighteen different approaches with equally confident advocates. Your pediatrician said something that sounded like advice but was actually a list of options. And you are in the middle of all of it, sleep-deprived to a degree that is affecting your ability to evaluate any of the information coming at you.

Sleep training is one of the most fiercely debated topics in early parenting, and the intensity of the debate is somewhat out of proportion to what the research actually shows. Here is what the science says, as plainly as possible.

What the Research Actually Shows

Multiple randomized controlled trials and longitudinal studies have examined sleep training methods across a range of approaches. The overall finding is that behavioral sleep interventions, including graduated extinction methods (sometimes called controlled crying or Ferber method), are effective at improving infant sleep outcomes without evidence of harm to attachment, emotional development, or parent-child relationship quality when studied at follow-up (Hiscock et al., 2007; Price et al., 2012).

The 2023 Study That Made HeadlinesA 2023 study published in BMJ Open (Whittall et al., 2023) examined sleep training methods including graduated extinction, bedtime fading, and a control group and found no significant differences in child emotional or behavioral outcomes, cortisol levels, or maternal mental health at follow-up. Notably, all sleep-trained groups showed improvements in maternal depression compared to the control group, suggesting that parental sleep and wellbeing are themselves a meaningful outcome. This study received significant media attention and is one of the more recent pieces of the evidence base on this topic.

Gentler approaches, including pick-up-put-down methods, camp-it-out variations, and other low-or-no-cry approaches, have less rigorous research support primarily because they are harder to study with consistency, not because they have been found ineffective. Families who use them report success, and there is no evidence that gentler approaches cause harm.

The research does not endorse one sleep training method above all others. It suggests that multiple approaches can work when applied consistently, and that parental wellbeing is a legitimate factor in the decision.

What the Research Does Not Say

The research does not say that all babies should be sleep trained, that sleep training must begin at a particular age, or that families who choose not to sleep train are harming their children. Co-sleeping and bedsharing, practiced safely according to safe sleep guidelines, are the norm in much of the world and are associated with successful breastfeeding and mother-infant closeness in research from those contexts.

The research also does not say that cry-it-out methods are risk-free for all families in all contexts. For parents who find the method deeply distressing, or for children with certain temperamental profiles or medical considerations, the method that produces the best outcome is the one the family can actually apply consistently and compassionately.

The Consistency FactorOne of the most consistent findings across sleep training research is that consistency matters more than the specific method. An approach applied inconsistently, where the response varies unpredictably from night to night, tends to produce worse outcomes than a gentler approach applied consistently. If you choose a method, applying it reliably is more important than which method you choose.

How to Find the Right Approach for Your Family

The right sleep approach for your family is the one that accounts for your child's temperament, your family's values, your own mental health and sleep needs, and the quality of your relationship with your child. A method that leaves a parent in significant distress, regardless of its evidence base, is not the right method for that family.

Sleep deprivation in parents is a genuine public health issue with measurable effects on mental health, emotional regulation, relationship quality, and parenting capacity. The research that considers parental wellbeing as an outcome takes this seriously. An exhausted parent who finds a method that works, even if it involves some crying, is not a parent who has chosen poorly. They are a parent who has chosen sustainability.

Finding the Right Approach

1Start with your own values and capacity.

The method you can apply consistently without causing yourself significant distress is the starting point. No research-supported method works if you cannot sustain it.

2Consider your child's temperament.

Highly sensitive children may need a slower, gentler approach to sleep changes. Very easy-going children may adapt quickly to a variety of methods. Your child's individual makeup matters.

3Prioritize consistency over method.

Whatever approach you choose, the research consistently shows that consistency in application produces better outcomes than the specific method. Choose something you can maintain reliably.

4Address your own sleep needs as seriously as your child's.

Parental sleep deprivation has real effects on parenting quality and mental health. If your sleep situation is unsustainable, that is a legitimate reason to make a change, regardless of which method you choose.

5Work with your pediatrician on timing and readiness.

Developmental readiness, current health status, and any medical considerations are worth discussing with your pediatrician before beginning a sleep training approach, particularly for very young infants.

Summary

The research on sleep training is more nuanced than either side of the debate tends to represent. Multiple approaches have evidence support. No single method is endorsed by the research for all families. Parental wellbeing is a legitimate and measurable outcome. Consistency matters more than method. The right sleep approach for your family is the one you can apply reliably, that fits your values, accounts for your child's temperament, and does not require you to sustain a level of distress that depletes you further. That is a reasonable and research-informed standard.

Frequently Asked Questions

Is cry-it-out harmful to babies?

The research available to date, including multiple randomized controlled trials and long-term follow-up studies, does not find evidence of harm to attachment, emotional development, or cortisol levels in babies who underwent graduated extinction sleep training methods. This research has limitations, and families should make decisions in consultation with their pediatrician.

What age is appropriate for sleep training?

Most sleep training approaches are not recommended before four to six months, when infant sleep architecture has begun maturing enough for independent settling to be developmentally possible. Your pediatrician can help you determine readiness for your specific child.

Is it okay to never sleep train?

Yes. Sleep training is a choice, not a developmental requirement. Many families successfully manage infant sleep without formal sleep training through a combination of feeding, cosleeping, and gradual developmental changes. The relevant question is whether the current sleep situation is sustainable for the whole family.

What is the Ferber method?

The Ferber method, developed by pediatric sleep specialist Dr. Richard Ferber, is a graduated extinction approach in which parents put the baby down drowsy but awake and check in at increasing intervals if the baby cries. It is one of the most studied sleep training approaches and has a substantial evidence base.

Can sleep training affect breastfeeding?

Some research suggests that night weaning, which may accompany certain sleep training approaches, can affect milk supply if breastfeeding is still established primarily at night. This is worth discussing with a lactation consultant or your pediatrician if you are breastfeeding and considering sleep training.

Sources

Hiscock, H., and Wake, M. (2007). Randomised controlled trial of behavioural infant sleep intervention to improve infant sleep and maternal mood. BMJ, 324(7345), 1062.

Whittall, C. et al. (2023). Behavioural and developmental outcomes of sleep training in infants. BMJ Open. doi.org/10.1136/bmjopen-2022-065056

American Academy of Pediatrics. Safe sleep recommendations. healthychildren.org

Sleep is one of the most complex and emotionally loaded topics of early parenting, and navigating it alone is harder than it needs to be. If you want a personalized, non-judgmental conversation about what might work for your family, Dr. Erica works one-on-one with parents of infants and toddlers. Visit becomingplayful.com.

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