Poster #64 - Changes in memory consolidation over nocturnal sleep as children transition out of naps

• In Event: Poster Session 09

Abstract

Sleep in early childhood is unique given the transition from a biphasic sleep pattern (midday nap and overnight sleep) to a monophasic sleep pattern (just overnight sleep). Naps benefit memory consolidation at this age, a benefit associated with sleep spindles and slow wave sleep. However, naps can also modify the physiology of subsequent overnight sleep. For instance, napping is associated with reduced slow wave sleep and reduced delta activity (i.e., slow wave activity; SWA) in subsequent overnight sleep. Given this, we predict differences in memory consolidation across overnight sleep based on nap presence and nap status (habitual v. non-habitual napper).
Participants are preschool-age children (33-71 months) who are habitual nappers (5+ naps/week) or non-habitual nappers (<2 naps/week). Children are presented with a visuospatial learning task in which they learn the locations of pictures on a grid. They encode one version of the picture locations, complete an immediate recall phase, and then a delayed recall phase following a 2-hr polysomnography-recorded nap period or an equivalent time spent awake (picture versions and conditions counterbalanced, 1 week apart). Children are tested the subsequent morning (24 hr recall phase). Polysomnography is recorded during the overnight sleep bouts in both conditions.
We hypothesize that when nap deprived, SWA in subsequent overnight sleep will be greater in habitual nappers than in non-habitual nappers (reflecting greater sleep pressure). However, this increase in SWA in habitual nappers may not be serving the same function for memory consolidation as in non-habitual nappers. That is, for non-habitual nappers, it may be that their brains are sufficiently mature to maintain memories long enough that overnight sleep allows them to consolidate information more efficiently. In contrast, habitual nappers may be vulnerable to interference and the damage to learning that comes from the missed nap is not restored following overnight sleep even though accumulated sleep pressure may lead to greater SWA. Thus, we additionally predict that non-habitual nappers will show greater memory consolidation over overnight sleep than habitual nappers.
An independent samples t-test will be conducted to assess whether SWA in habitual and non-habitual nappers is significantly different. To examine whether non-habitual nappers and habitual nappers differ in their memory consolidation, a repeated measures ANOVA will be conducted assessing the effects of Napping Status (habitual vs. non-habitual) and Condition (nap vs. no-nap) on the change in recall accuracy across the interval (following the nap/no-nap condition and overnight sleep).

Authors

• Sanna Lokhandwala, University of Massachusetts Amherst
  Presenting Author

• Rebecca Spencer, University of Massachusetts, Amherst