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Author ORCID Identifier

https://orcid.org/0000-0002-4704-8138

AccessType

Open Access Dissertation

Document Type

dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Psychology

Year Degree Awarded

2024

Month Degree Awarded

February

First Advisor

Rebecca M.C. Spencer

Second Advisor

Kirby Deater-Deckard

Third Advisor

Holly Laws

Fourth Advisor

Sara Whitcomb

Subject Categories

Cognitive Neuroscience | Developmental Neuroscience | Developmental Psychology | Development Studies | Laboratory and Basic Science Research | Other Physiology

Abstract

Preschool-age children often distribute their sleep across a midday nap and overnight sleep. Skipping the nap is suggested to increase the duration and depth of deep sleep (i.e., slow wave activity; SWA). Moreover, missing the midday nap has been shown to impair learning processes. This may be because children’s brains at this point in development are immature, necessitating the intervening nap period to strengthen memories before they are forgotten. Nonetheless, at some point during the preschool years, many children begin transitioning naturally out of napping. It is unclear whether the memory benefits of overnight SWA after a skipped nap depend on children’s baseline nap frequency. To this end, Chapter 2 of my dissertation sought to examine how the consolidation of memory over nocturnal sleep changes across the nap transition. Habitually and non-habitually napping children were taught a declarative task in the afternoon, and memory was probed following a polysomnography-monitored nap and following an equivalent period of wake. Memory was also examined 24-hours later in the afternoon following polysomnography-monitored overnight sleep. While children performed better over overnight sleep had they been awake during nap time the day prior, performance was not related to overnight SWA. However, when SWA was divided into slow and fast SWA, both measures were negatively associated with performance following overnight sleep. While it is known that children transition out of naps, the mechanism behind this transition is unclear. Considering that early childhood is a time of significant changes in both sleep and the brain, it is possible that the cessation of napping may have to do with brain development. To this end, Chapter 3 examined the relations between changes in SWA and hippocampal body volume longitudinally. Hippocampal body volume decreased over time, for both habitual nappers and those who transitioned out of the nap. However, SWA decreased over time only for children who transitioned out of naps. Collectively, the results of this dissertation suggest that the transition out of napping may be indicative of more mature brains (Chapter 3) and therefore a single overnight bout of sleep may be efficient for the consolidation of memories (Chapter 2).

DOI

https://doi.org/10.7275/36337085

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