1. Starting questions
What effect does insufficient sleep have on infants, toddlers, and their parents?
What evidence exists for sleep training? Does it have positive or negative effects on the baby — and in particular on the parent–child bond?
2. Summary of findings
Sleep problems in infancy affect approximately 20–30% of children. They can become chronic and persist until preschool age.
Poor sleep negatively affects the socio-emotional development of babies and toddlers and increases the risk of obesity in preschool age.
Persistent short sleep duration brings long-term negative effects on children’s health and quality of life.
Nearly half of mothers who seek advice at sleep clinics are already in the clinically relevant range for depressive symptoms. Over 80% lose those symptoms after sleep training.
94% of studies confirm the effectiveness and positive long-term impact of behavioral interventions for sleep problems (based on a meta-analysis covering 50+ studies).
No emotional or psychological harm related to sleep training was found within a 5-year follow-up period.
Repeated positive effects on the baby, maternal mood, parent–child bond, and the overall family were demonstrated.
3. Background
Even though the effectiveness of sleep training is hard to dispute, the topic remains one of the most controversial in the field of infancy and toddlerhood. Particularly the aspect of “letting babies cry” and fears about negative consequences unsettle parents — and often medical professionals too.
But what is myth? And what is scientifically proven?
After more than 30 years of research and over 100 studies on sleep problems and sleep training — what does science recommend?
4. Definitions
The term “sleep problems” in infants and toddlers is difficult to define precisely. It is generally understood to mean frequent nighttime waking (2 or more times) in babies from 4–6 months of age.
“Sleep training” refers to behavioral interventions aimed at improving sleep problems in infants and toddlers. The studies analyzed here primarily use two methods:
Method A
Unmodified extinction
Also called “cry it out”. The baby is allowed to cry without parental presence until they fall asleep independently.
Method B
Graduated extinction
Controlled crying / Ferber method. Parents briefly check in at regular, gradually increasing intervals.
Note: In the German-speaking world, almost exclusively gentler sleep coaching methods are used today, which allow parental presence in the room. According to the experience of sleep consultants worldwide, these can be equally effective when implemented consistently — and are easier on parents’ conscience.
5. Effects of sleep problems on child, mother and family
5.1 Crying and sleep problems as a cause of marital tension
A Dutch study¹ of 107 married couples found that infant crying in the first year of life was a major cause of dissatisfaction and tension in marriage. The study underscores the importance of educating new parents about treatment options for their baby’s sleep problems.
5.2 Short sleep duration and risk of obesity
An Israeli study² found that short sleep duration was associated with significant weight gain in the first six months of life. An American study³ of 915 children showed that infants sleeping fewer than 12 hours per day had a significantly higher risk of obesity at age 3.
5.3 The importance of naps for learning and memory
An American study⁴ with 15-month-old toddlers showed that those who napped after learning an artificial grammar retained the pattern better, while those without a nap retained nothing. This confirms the important role of naps in promoting long-term memory in early childhood.
5.4 Impact of sleep duration on health and quality of life
A comprehensive Australian longitudinal study⁵ analyzing the sleep behavior of 2,926 children identified four different sleep duration types. Persistent short sleepers had significantly worse physical, emotional, and social health than normally sleeping peers.
5.5 Socio-emotional problems due to sleep deprivation
A 2017 US study⁶ of 117 mother–child pairs found that insufficient sleep in babies and toddlers correlates with a range of psychological problems including anxiety, depressive symptoms, and social inhibition.
5.6 Link between infant sleep problems and maternal depression
45% of mothers who sought help at an Australian sleep clinic due to their baby’s sleep problems showed signs of postnatal depression at clinically relevant levels⁷. These findings highlight the need for appropriate support for mothers dealing with their baby’s sleep challenges.
6. Sleep training — application, safety, and effects
6.1 Reduction of maternal depression through coaching and sleep training
An Australian study⁸ showed that a single consulting session on sleep information and sleep training produced significant improvements in infant sleep problems and maternal mental wellbeing — including a dramatic reduction in stress levels, anxiety, and depression. The number of mothers with depression fell by 85%.
Mothers’ depression rate fell by 85% after their baby’s sleep improved.
6.2 No negative effects on parent–child bond or later emotional health
An Australian study⁹ of 43 infants examined the effects of two sleep training methods. Both led to significant improvements in sleep, with no negative effects on stress levels, parent–child bond, or emotional and behavioral wellbeing after one year.
6.3 Real-world application of sleep training
A study¹⁰ of 2,090 parents in the US found no significant differences in maternal depression or parent–child relationship when comparing either sleep training method with a no-intervention control group. This confirms that sleep training is effective and safe in real-world conditions.
6.4 Reduction of nighttime waking and improvement in parental quality of life
A 6-week US study¹¹ with 235 infants showed that sleep training significantly reduced serious sleep problems and nighttime waking while simultaneously improving parental fatigue, sleep quality, and mood.
6.5 Marked improvement in behavior and wellbeing — especially in anxious babies
A Swedish study¹² of 94 families showed that sleep training — teaching children aged 4–45 months to fall asleep independently — led to improved sleep patterns, daytime behavior, and family health after just two weeks. Notably, previously anxious and insecure babies showed the most pronounced improvements in behavior and wellbeing.
6.6 No long-term negative effects on emotional or mental health
A 5-year Australian follow-up study¹³ found no significant differences in emotional and mental health at age six between children who had received sleep training as infants and those who had not. No differences in parent–child bond, conflict behavior, attachment, or parental depression were found.
After 5 years: no differences in parent–child bond, emotional health, or mental wellbeing.
6.7 Recommendations from the American Academy of Sleep Medicine
The AASM recommends, based on an analysis of 52 studies¹⁴, early use of behavioral methods to treat sleep problems in children. These are not only effective and safe, but also produce lasting improvements. Methods specifically recommended include Extinction, Graduated Extinction, Bedtime Fading, preventive parent education, and scheduled wake times.
7. Conclusions
In summary, sleep training has been shown to be both effective and safe. The extensive body of research clearly demonstrates that sleep patterns in babies and toddlers, as well as the psychological wellbeing of the entire family, improve rapidly and durably through sleep programs.
For parents struggling with their baby’s sleep difficulties, these methods offer valuable support. It therefore seems crucial that both parents and healthcare professionals are well informed.
Parents deserve to be educated about healthy baby sleep and to receive the information and support they need to effectively resolve persistent sleep problems.
“We hope this article helps to understand the severity of infant sleep problems and their massive impact on the entire family — and that it has taken some of the fear away from recommending or using strategies to improve baby sleep.
It’s important to know that today there are many gentle and alternative methods to the harder, classic sleep training approaches analyzed here. And what remains clear: even these harder methods showed no negative effects.
At Land of Little Dreamers, we recommend 5 attachment-oriented methods that are equally effective and all allow parental presence in the room. It doesn’t have to be ‘cry it out’ — there are many paths to helping exhausted parents and overtired babies.”
References
- ¹ Meijer AM, van den Wittenboer GL. Contribution of infants’ sleep and crying to marital relationship of first-time parent couples in the 1st year after childbirth. J Fam Psychol. 2007;21(1):49–57.
- ² Tikotzky L et al. Sleep and physical growth in infants during the first 6 months. J Sleep Res. 2010;19(1):103–10.
- ³ Taveras EM et al. Short sleep duration in infancy and risk of childhood overweight. Arch Pediatr Adolesc Med. 2008;162(4):305–11.
- ⁴ Hupbach A et al. Nap-dependent learning in infants. Dev Sci. 2009;12(6):1007–12.
- ⁵ Magee CA, Gordon R, Caputi P. Distinct developmental trends in sleep duration during early childhood. Pediatrics. 2014;133(6):e1561–e1567.
- ⁶ Mindell JA et al. Sleep and social-emotional development in infants and toddlers. J Clin Child Adolesc Psychol. 2017;46(2):236–246.
- ⁷ Hiscock H, Fisher J. Sleeping like a baby? Infant sleep: impact on caregivers and current controversies. J Paediatr Child Health. 2015;51(4):361–4.
- ⁸ Symon B et al. Reducing postnatal depression, anxiety and stress using an infant sleep intervention. BMJ Open. 2012;2(5):e001662.
- ⁹ Gradisar M et al. Behavioral interventions for infant sleep problems: a randomized controlled trial. Pediatrics. 2016;137(6):e20151486.
- ¹⁰ Kahn M, Barnett N, Gradisar M. Implementation of behavioral interventions for infant sleep problems in real-world settings. J Pediatrics. 2022.
- ¹¹ Hall WA et al. A randomized controlled trial of an intervention for infants’ behavioral sleep problems. BMC Pediatr. 2015;15:181.
- ¹² Eckerberg B. Treatment of sleep problems in families with young children. Acta Paediatr. 2004;93(1):126–34.
- ¹³ Price AM et al. Five-year follow-up of harms and benefits of behavioral infant sleep intervention. Pediatrics. 2012;130(4):643–51.
- ¹⁴ Morgenthaler TI et al. Practice parameters for behavioral treatment of bedtime problems and night wakings in infants and young children. Sleep. 2006;29(10):1277–81.