Summary: A University of Arizona study reports that while afternoon naps support memory and learning in typically developing preschoolers, naps may worsen memory retention in children with Down syndrome.
Researchers at the University of Arizona have found that naps do not benefit all children equally. For typically developing preschoolers, a nap shortly after learning boosts memory retention, but in children with Down syndrome, napping was associated with poorer retention of newly learned words.
The study tested whether natural, in-home naps supported memory consolidation in two groups of young children: 24 typically developing children (average age about 2.5 years) and 25 children with Down syndrome (average age about 4.5 years). Both groups had comparable scores on basic cognitive assessments and were habitual nappers who regularly slept during the day.
The research team visited families in their homes to teach each child a set of novel words paired with pictures of unfamiliar objects. The made-up labels—words like “tobe,” “wame,” “bope” and “neek”—were constructed to resemble English words but ensured that every child was hearing them for the first time.
Retention was assessed at multiple intervals: five minutes after learning, four hours after learning following a period of wakefulness, four hours after learning when the child took a nap soon after the learning session, and again 24 hours later to measure longer-term retention. Testing in the children’s natural home environment allowed the researchers to follow typical nap schedules and avoid disrupting normal sleep patterns.
Results showed a clear difference between the two groups. Typically developing children who took an approximately 90-minute nap shortly after learning retained new word–object associations better at both the four-hour and 24-hour tests than when they stayed awake. In contrast, children with Down syndrome performed worse after naps: retention at the four-hour and 24-hour intervals was poorer when they napped after learning than when they remained awake.
Sleep-stage differences between groups may help explain these opposite effects. The study recorded sleep stages during naps using home-based polysomnography and tracked overall sleep quality with wrist-worn activity monitors and parent sleep logs. Forty-four percent of the children with Down syndrome did not enter REM sleep during their naps, compared with about six percent of the typically developing children. Previous research suggests that interactions between REM sleep and deep non-REM (slow-wave) sleep contribute to memory consolidation. Reduced REM sleep or interrupted progression through sleep stages—conditions that are more common in Down syndrome and often associated with sleep problems such as sleep apnea—could disrupt the consolidation process.
“In children with Down syndrome, there was something about napping right after learning that seemed to interfere with retention, which contrasts with the benefit we saw in typically developing children,” said Jamie Edgin, associate professor of psychology at the University of Arizona and senior author of the study. “REM sleep appears to be a promising factor to examine, because incomplete or insufficient REM during a nap may be linked to poorer memory outcomes.”
First author Goffredina Spanò, who conducted the home visits during her doctoral work at the UA Department of Psychology, emphasized the ecological approach. The team deliberately avoided lab-based sleep testing to preserve each child’s normal routine and comfort. The wake condition was scheduled at times when children would not normally nap, so the study did not involve sleep deprivation.
The observed pattern—naps benefiting typical preschoolers but hindering children with Down syndrome—persisted even after an intervening night of sleep. That suggests the nap-related difference in consolidation has lasting effects on learning across a full day.
The findings have practical and clinical implications. Sleep quality and sleep stage composition may influence how children with developmental disorders learn and retain information. Clinical trials and interventions for children with Down syndrome may need to consider sleep as a key variable when assessing learning outcomes and treatment effects. Edgin’s lab is exploring whether altering nap routines could be a useful intervention to improve learning in children with Down syndrome.
About the research
The study, published in Proceedings of the National Academy of Sciences, is titled “REM sleep in naps differentially relates to memory consolidation in typical preschoolers and children with Down syndrome.” It demonstrates that naps are not universally beneficial for learning: in healthy preschoolers, REM-rich naps appeared to support memory consolidation, while in children with Down syndrome—many of whom experienced reduced or absent REM during naps—napping was associated with increased memory loss.
Funding and collaborators: The research was supported in part by the Molly Lawson Foundation, Jerome Lejeune Foundation, and LuMind Research Down Syndrome Foundation. Collaborators included Rebecca Gómez, Bianca Demara and Stephen Cowen from the UA Department of Psychology and Mary Alt from the UA Department of Speech, Language and Hearing Sciences.
The authors caution that additional work is needed to pinpoint the precise mechanisms linking sleep stages to memory outcomes and to determine whether changes to nap timing or duration could improve learning for children with Down syndrome. For clinicians, educators, and parents, these results underscore the importance of considering sleep quality and sleep architecture when designing learning activities or interventions for young children, especially those with developmental disorders.