Boosting Baby’s Brain

Uncovering the Causal Effects of Sleep in Infant Cognitive Development

Babies spend most of their time asleep, and the critical importance of sleep for their development has long been recognized. Much of the research on sleep’s impact on cognitive development has historically been correlational, such as findings that infants with stable circadian rhythms have broadly higher cognitive performance. 

The correlational nature of these studies prevents understanding causation; it is equally possible that increased development leads to improved sleep as it is that improved sleep leads to increased development.  Recently, researchers have used experimental approaches to address this question of causality.  

Photo by Ivone De Melo |

FABBS journal Policy Insights from the Behavioral and Brain Sciences(PIBBS) published the article: “Infant Sleep as a Cornerstone for Cognitive Development,” by Dr. Sabine Seehagen, a psychology professor at Ruhr University in Germany. In the article, Dr. Seehagen reviews the importance of sleep for infant cognitive development, particularly memory, and provides evidence-based recommendations for policy and practice.  

In one approach, researchers assign infants to different experimental groups to assess how sleep affects memory formation. Within one group, infants receive learning experiences right before periods of extended sleep, and in the other, they learn right before periods of wakefulness. Additionally, in some studies all infants then receive a second, delayed period of sleep, to assess how the timing of sleep affects memory and to account for general fatigue.  

These studies have shown that sleep soon after learning experiences improves memory formation and later application of memory. Two such studies found that infants who took a nap shortly after seeing a face were able to recognize it and infants that sleep shortly after receiving new information improve their ability to solve problems and detect language principles. 

Together, observational and experimental research points to proper infant sleep as being critical to cognitive development, such as learning and memory processes. These findings have several key implications for policy and practice, as Dr. Seehagen summarizes:  

  • Childcare settings should reconsider standard sleep windows. Research shows that sleep schedules, frequencies, and durations are highly variable between infants, and missing a naturally occurring nap has detrimental cognitive consequences. Settings such as daycares should provide personalized schedules for infants and particularly encourage sleep after stimulating experiences and social interactions.  
  • There should be increased research communication to caregivers. While there is strong literature on how to best parent infant sleep health, there is inadequate communication of this research to those who need it. Development of fact sheets, phone apps, and community resources could provide immediate benefits to caregivers and their infants.  
  • Nurseries and early childhood educators should consider sleep schedules in their daily plans. Learning activities should likely take place near naptime, rather than shortly after waking, to increase knowledge retainment. Additionally, educators should be made aware of signs of sleepiness so that they can best support each individual child.  
  • Parents should be given flexible parental leave arrangements and working hours. Though expensive, extended paid periods of parental leave are recommended for several reasons. First, inflexible working hours reinforce parent’s own sleep deprivation, which increases risk for mental disorders such as postpartum depression and reduces caregiving ability. Second, increased flexibility enables parents to allow infants to sleep according to their needs, rather than based on externally determined schedules, which would improve infant cognitive development.  

Overall, developmental research has made key progress into the causal relationships between infant sleep quality and their cognitive development. Childcare practice and policy recommendations related to improving sleep quality, personalizing schedules to each infant, and providing paid parental leave will better support infant development.  

Child Health and Human Development