0321 Increased Slow-Wave Activity Predicts Slower Processing Speed in Toddlers

Introduction

Slow-wave activity (SWA) shows an inverted U-shaped time course during development. Specifically, maximal SWA undergoes a posteroanterior shift from 2 to 20 years of age, which may reflect cortical maturation. Previously, we showed that greater slow sigma power during sleep predicted faster reaction time in preschool-aged children. To date, little is known about the relationship between SWA and processing speed (PS), a basic fundament underlying complex cognitive skills in early development.

Methods

This project examined the relationship between SWA and PS in 2.5-3.0-year-old children (n=26, 50% males) via home-based assessments. After a 5-day stabilization sleep schedule, a baseline sleep EEG recording was performed on participants at 4 electrode placements: Fz, Oz, C3, and C4. SWA EEG spectral power was quantified in the 0.75-4.5 Hz rangeduring the first 60 minutes of NREM sleep. PS was obtained as part of a standard cognitive assessment via a computer-based task one hour after waking from a midday nap.

Results

On average, reaction time (PS) was 2111 ± 08 ms and SWA was 856.4 ± 300.7 µV2/Hz. Increased SWA in the occipital region was predictive of a longer reaction time and therefore slower PS (r = 0.44, p = 0.03). This relationship showed differences between sexes, suggesting that females (r = 0.26, p = 0.07) may show a stronger association between SWA in the occipital brain region and PS than males (r = 0.09, p = 0.33).

Conclusion

Interestingly, these findings contradict our hypothesis based on previous data with older children indicating that greater SWA was associated with more advanced behavioral and cognitive skills. This discrepancy may reflect the stark individual differences present within this rapidly maturing age group.

Support

Research support from NIH R01-MH086566 to MKL.

0322 Napping, Inhibitory Control, and Self-Regulation in 2-Year-Old Children

Introduction

Poor sleep in early childhood is linked to reduced school readiness. This study examined the role of acute sleep loss in behavioral self-regulation using a delay of gratification task. We hypothesized that after acute nap deprivation, toddlers would have worse inhibitory control and resort to more maladaptive self-regulation strategies than after a nap.

Methods

25 healthy children (11 males, 34.1±2.3 months-old) followed a strict sleep schedule for ≥5 days before a baseline (nap) and an acute nap deprivation condition (no-nap). After being introduced to an age-appropriate toy, children were instructed not to touch the toy and left alone for 3-minutes. To assess inhibitory control, videos of the waiting period were behaviorally coded for latency to touch and 11 self-regulation strategies. We combined strategies into adaptive and maladaptive composites; higher scores on each composite indicated greater use.

Results

During the nap condition, 19 children touched the toy (latency to touch=70.0±60.7 sec); during the no-nap condition, 18 children touched the toy (latency to touch=65.4±71.6 sec). The adaptive composite score was 1.58±0.25 for the nap condition and 1.17±0.27 for the no-nap condition. The maladaptive score was 0.92±0.17 for the nap condition and 0.83±0.19 for the no-nap condition. We found no differences between conditions in the number of children who touched the toy (X2=0, p=0.50), mean latency to touch (t=0.27, p=0.39), or the composite scores of adaptive (z=0.35, p=0.12) and maladaptive strategies (z=0.09, p=0.69).

Conclusion

Findings indicate that acute nap deprivation may not have an immediate impact on inhibitory control and self-regulation in toddlers. 30-36 months old children may not have sufficient cognitive resources to exert inhibitory control and self-regulate whether or not they have obtained adequate daytime sleep. Future research should examine developmental changes in the effects of acute sleep restriction on behavioral self-regulation.

Support

Research support from NIH R01-MH086566 to MKL.

0338 Interactions Between Sleep, Stress Reactivity and Cognition in Early Childhood

Introduction

During early childhood, sleep impacts the development of the cognitive, behavioral and stress systems. Specifically, acute sleep restriction reduces the subsequent cortisol awakening response, predicts self-regulation strategies and moderates correlations between self-regulation strategies and response inhibition. However, little is known about the interaction between sleep, stress reactivity and cognition in early childhood. This preliminary cross over study aimed to determine how acute sleep restriction moderates the relationship between stress reactivity and cognition in 4-year-olds.

Methods

Healthy children (N=17; 57.4 months +/- 2.1; 10 female) participated in a sleep restriction protocol that included counterbalanced cognitive and behavioral assessments during baseline and sleep restriction conditions. An age appropriate inhibitory control task was administered and salivary cortisol samples (N=6) were collected during the task. Mean processing speed was measured, and stress reactivity was computed as area under the curve with respect to ground (AUCg).

Results

Two tailed correlation analyses were performed to examine the relationship between AUCg and mean processing speed. Under baseline conditions, AUCg and mean processing speed were positively associated (r=0.45; p=0.05). When children were sleep restricted, there was no association between AUCg and mean processing speed (r=0.05; p=0.83). Although not statistically significant, AUCg was predicted by an interaciton between sleep condition and mean processing speed B=-1.92; p=0.06).

Conclusion

These results suggest that healthy sleep may promote the coupling of stress and cognitive systems, which is likely adaptive when facing life’s challenges in early childhood. Examining the developmental trajectory of these interactions and incorporating individual difference factors will build upon this model that may eventually be applied in intervention approaches to sleep, stress and behavioral problems in preschool-aged children.

Support

NIH R01-MH086566 to Dr. Monique LeBourgeois

0333 Electronic Media Use is Associated with Poor Sleep In 3-6 Year-Old Children

Introduction

Recent surveys estimate that electronic media use among young children is increasing and that behavioral sleep problems are prevalent. In this study, we employed assessments of sleep and media use and tested the hypothesis that poor sleeping children would be more likely to engage with media than good sleeping children.

Methods

Participants were 44 children from two different cohorts: (1) Healthy, good sleepers (n=26, 13 males, 4.3±0.4 years) who reportedly obtained ≥10.5 hours per night and had no behavioral sleep problems and (2) Poor sleepers (n=18, 9 males, 5.5±0.7 years) who reportedly obtained chronic insufficient sleep ≤9 hours per night and/or had behavioral sleep problems for ≥6 months. Sleep duration and sleep onset latency (SOL) were quantified through 7 nights of actigraphy and verified with sleep diaries. Media use, defined as any electronic device involving screen time that engages children, was assessed across 2 weekdays and 2 weekend days through a parental media diary. Independent t-tests compared the duration of media use and actigraphy variables between groups.

Results

Poor sleeping children on average had longer SOL (28.6±17.9 vs. 17.3±8.66 minutes, t=-2.5, p<0.05) and shorter sleep duration (589.6±37.5 vs. 627.4±27.4 minutes, t=3.7, p<0.01) compared to good sleeping children. Additionally, average daily media use (125.1±88.5 vs. 66.5±48.3 minutes, t=-2.6, p<0.05), evening media use (22.0±21.3 vs. 4.2±10.4 minutes, t=-3.3, p<0.01), and weekend media use (154.4±105.9 vs. 79.8±55.6 minutes, t=-2.7, p<0.05) duration was higher in poor than good sleepers.

Conclusion

Our findings indicate that media use duration and timing likely play an important role in early childhood sleep health. Young children who use more evening media are more likely to take longer to fall asleep and have shorter sleep duration overall. Time displacement (time spent using media instead of sleeping), psychological stimulation, and the effects of screen light on circadian timing are potential mechanisms underlying these associations.

Support

NIH R01-MH086566 and R21-MH110765 to MKL