Exploring Differences in Hippocampal Structure between Habitual vs Non-habitual Nappers during Early Childhood

Abstract

When we sleep, our memories are consolidated and become less vulnerable to interference, both during overnight sleep and during naps. Previous research in adults suggests this effect is at least partially due to a “transfer” of these memories from the hippocampus to the cortex. Although a similar process likely takes place in young children, there is little research investigating it. The existing literature suggests habitually napping children may need naps more than non-habitually napping children because their brain is less mature. This study aims to examine relations between habitual versus non-habitual nappers and brain development in early childhood. The focus was on the hippocampus, a structure that is critical for memory and shows protected development during early childhood. At the time of this report, 21 children provided useable data (Mage = 4.49 years, SD = 0.51, 9 female). Of these participants, 8 were habitual nappers and 13 were non-habitual nappers. Hippocampal volumes were extracted using a combination of manual and automated methods. Results revealed in the left hippocampal tail, habitual nappers had larger volumes compared to non-habitual nappers. Although these are preliminary results and do not survive correction for multiple comparisons, the findings support that variation in hippocampal development may relate to nap status in developing children. Future research will examine a larger sample size and investigate other brain regions to determine the specificity of these effects.