New research suggests that napping is beneficial for memory processing in early childhood. The study, published in Child Development, found that the combination of napping and overnight sleep improves retrieval of emotional memories compared to overnight sleep alone. The findings highlight the importance of naps in supporting memory and emotional processing in young children.
The study sought to investigate the impact of napping on emotional memory consolidation in early childhood. Specifically, the researchers wanted to determine if naps protect emotional memories from interference, indicating consolidation, or if napping only prepares memories for consolidation during overnight sleep. The study focused on emotional memories in the domain of social learning.
“We were led to this question from two directions. First, our work on naps in children showed us that naps at this age (preschool age, 3-5 yrs) benefit learning. Second, our work in adults has shown us that sleep is really important for emotional memory processing. So this led us to consider whether the naps in children benefit emotional processing,” explained study author Rebecca Spencer, a professor of psychological and brain sciences at the University of Massachusetts, Amherst.
The study involved 63 participants, aged 33 to 67 months, enrolled in preschools in western Massachusetts. Eligible children had normal or corrected-to-normal vision and no reported developmental, learning, sleep, or neurological disorders.
The participants were divided into two groups: an interference group and a no-interference group. The groups were matched in terms of age, sex, household income, and race/ethnicity. There were no significant differences in nap length or nap habituality between the groups. Children’s self-reported sleepiness and mood were also similar across the nap and wake conditions.
The task used in the study involved an emotional memory task adapted from previous research. During the encoding phase, neutral face images were paired with audio recordings presented through headphones. The audio consisted of neutral or mean descriptions referencing the faces, aiming to associate them with age-appropriate neutral or rule-violating actions.
The study included three recognition phases: immediate, delayed, and 24-hour recognition. Immediate recognition occurred right after the encoding phase, delayed recognition took place about 30 minutes after the child’s nap or equivalent wake period, and 24-hour recognition occurred the following morning, approximately 24 hours after the encoding phase.
In each recognition phase, children were presented with a simple memory task. They had to select the familiar face from a pair, which included one face from the encoding phase and one novel distractor face of the same gender.
The procedure involved two testing conditions: nap promotion and wake promotion. Each child participated in both conditions, with the order counterbalanced across participants. The encoding phase and immediate recognition phase were completed in the morning. Afterward, children returned to their normal classroom routine until the nap opportunity, during which they were either promoted to nap or to stay awake.
The interference group underwent the interference phase after their nap or wake intervals, followed by delayed recognition. During the interference phase, participants were exposed to stimuli that were unrelated to the emotional faces they had initially encountered. This was designed to create interference between the initial encoding of the emotional faces and the subsequent memory retrieval.
Spencer and her colleagues found that napping (without interference) provided immediate and next-day benefits to children’s emotional memory performance. In the interference group, napping showed mixed results depending on the emotional valence of the faces, while in the no-interference group, napping consistently improved memory accuracy over the 24-hour period.
Simply put, participants who napped the previous day showed improved face recognition. This suggests that the combination of napping and overnight sleep enhances the retrieval of emotional memories compared to overnight sleep alone.
“This study shows us that naps are important at this age,” Spencer told PsyPost. “They support memory and emotional processing and these functions can’t be made up for by overnight sleep – most kids need both naps and overnight sleep and when we withhold these, their memory and emotional reactivity can be compromised.”
“So until a child is ready to transition out, we should not push them. This is particularly important because with the move to universal pre-K, these preschools are not always allowing for a nap opportunity which could be counter-effective to the benefits of preschool.”
Surprisingly, the researchers observed a marginal memory decay effect for negatively valenced faces after napping. Although naps initially seemed to destabilize emotional memories in the short term, previous research has shown that this destabilization can lead to longer-term memory stability and enhanced consolidation.
“Initially we thought naps would give an immediate memory benefit but here we show for an emotional memory, right after the nap the memory gets worse, it is destabilized by sleep,” Spencer explained. “However, these are the memories that then do the best following subsequent overnight sleep so they still ‘win’ in the end. It just suggests a different mechanism as to how the memory evolves.”
The study’s findings provide valuable insights into how naps and overnight sleep interact during the processing of emotional memories. However, it is unclear whether naps are equally beneficial for emotional learning in children who are transitioning away from napping and those who nap regularly. Due to a small number of non-habitual nappers in the study, further analyses were not possible.
“It’s important to consider how these effects change as kids transition out of naps,” Spencer said. “As these were almost all habitual nappers, we could not discern how this changes as they are developmentally read to transition out of naps.”
The study, “Early childhood naps initiate emotional memory processing in preparation for enhanced overnight consolidation“, was authored by Olivia Hanron, Gina M. Mason, Jennifer F. Holmes, and Rebecca M. C. Spencer.