Nap Condition Research Articles

Age-related differences in problem-solving skills: Reduced benefit of sleep for memory trace consolidation

We investigated the behavioural and neuronal functional consequences of age-related differences in sleep for gaining insight into novel cognitive strategies. Forty healthy young adults (20–35 years), and twenty-nine healthy older adults (60–85 years) were assigned to either nap or wake conditions. Participants were trained on the Tower of Hanoi in the AM, followed by either a 90-minute nap opportunity or period of wakefulness, and were retested afterward. Functional magnetic resonance imaging scans examined differences in brain activation from training to retest in young versus older adults as a function of sleep. Sleep enhanced performance and transformed the memory trace in young adults via hippocampal-neocortical transfer, but not older adults. This is consistent with the notion that as the consolidation of a newly formed memory trace progresses, the hippocampus becomes less involved; especially so when sleep occurs during that time. These results demonstrate a critical role for sleep in supporting problem-solving skills and suggest that the benefit of sleep for consolidation of these skills is reduced with age.

P 87 Slow wave sleep of a 90-minute nap relates to hippocampus-dependent spatial memory consolidation

Introduction : The hippocampus is critical for learning and consolidation of behaviourally-relevant spatial information. During spatial learning, spatially-related firing patterns of hippocampal place cells reflecting the subjects‘ location can be detected. It is widely acknowledged that the stabilization of newly encoded memory traces during active system consolidation is promoted by post-learning slow wave sleep (SWS). Here, hippocampal neural sequences are reactivated (“replay”) accompanied by neocortical slow oscillations thereby synchronizing spindle-ripple events originating from hippocampal and thalamic regions. Studies in rodents and humans reported a facilitation of spatial memories after full nights of sleep, in particular in early sleep SWS (i.e., sharp-wave ripples and slow waves). In this ongoing study, we investigated the effect of a 90-min nap on sleep-associated memory consolidation of spatial information. The advantage of an isolated nap condition is the possibility to selectively study the effect of SWS on memory consolidation. Patients & Methods: Forty healthy students between 21 and 32 years were divided into a sleep group (24±1,64 years, 55% female) and a wake group (24±2,68 years, 55% female). For testing spatial learning, the Virtual Water Maze (VWM), a digitalised version of the established Morris Water Maze Test for hippocampus-dependent place learning was used. Here, students had to find a treasure box hidden in the same position on a virtual island. Between learning and the recall sessions of the VWM (90 minutes), students either performed a mid-day nap accompanied by polysomnography (sleep condition) or watched emotionally neutral documentaries (wake condition). The improvement in the recall session was then compared between the groups and the influence of EEG sleep measures was analysed. Results: We found a significant positive correlation between spatial memory consolidation and time spent in SWS (SWS [min]: r=0,612, p=0,004). Accordingly, there was a tendency of a stronger consolidation when amounts of slow oscillations and sleep spindles were higher. When directly compared, there was no significant difference in the various consolidation measures of VWM between the groups . Conclusion: We found that consolidation of hippocampus-dependent spatial memory in a young healthy population was related to longer time spent in SWS as well as the amount of sleep spindles and slow oscillations during NonREM sleep of a 90-minute nap. Our data support the notion that the efficacy of hippocampus-dependent spatial memory consolidation depends on the duration of SWS.

Prior sleep timing and visual recognition of emotional faces in 6-month-old infants

Face recognition is an important mnemonic ability for infants when navigating the social world. While age-related changes in face processing abilities are relatively well documented, less is known about short-term intra-individual fluctuations in this ability. Given that sleep deprivation in adults leads to impairments in information processing, we assessed the role of prior sleep on 6-month-old infants’ (N = 17) visual recognition of faces showing three emotional expressions (neutral, sad, angry). Visual recognition was inferred by assessing novelty preferences for unfamiliar relative to familiarized faces in a visual recognition memory paradigm. In a within-subject design, infants participated once after they had recently woken up from a nap (nap condition) and once after they had been awake for an extended period of time (awake condition). Infants failed to show visual recognition for the neutral faces in either condition. Infants showed recognition for the sad and angry faces when tested in the awake condition, but not in the nap condition. This suggests that timing of prior sleep shapes how effectively infants process emotionally relevant information in their environment.

Effects of 2-hour nighttime nap on melatonin concentration and alertness during 12-hour simulated night work.

A nighttime nap is expected to mitigate melatonin suppression during night work by blocking light input to the retina, but it is unclear. In the present study, we investigated the effects of a nap break on melatonin level, subjective sleepiness, and vigilance performance during simulated night work. Eleven healthy young males (mean ± SD age: 22.2 ± 4.1 years) participated in counterbalanced crossover design experiments with two conditions (nap vs. no nap). The subjects performed 12-hour simulated night work from 21:00 to 09:00 h (illuminance: ∼500 lx). Subjects with a nap condition took a nap for 2 hours in a dark room from 03:00, while subjects with a no nap condition continued the simulated night work. The results showed that immediately after the 2-h nap break, the melatonin level at 05:00 h temporarily recovered from light-induced melatonin suppression during the simulated night work but significantly suppressed again at 07:00 and 09:00 h. Subjective alertness and vigilance performance were impaired immediately after the nap break but subsequently enhanced. The results suggest that a single nap break for 2 hours could be a strategy to enhance alertness during the last part of night shift but inadequate for mitigating melatonin suppression.

Mental health and sleep habits/problems in children aged 3\u20134 years: a population study

BackgroundSleep is essential for mental health at all ages, but few studies have investigated the importance of sleep for mental health in early childhood. Therefore, this study examined the association between mental health and sleep habits/problems in children aged 3–4 years.MethodsChildren aged 3 to 4 years who were living in the community (n = 415; 211/204 boys/girls) were recruited for this study. Their mental health was assessed using the Strengths and Difficulties Questionnaire (SDQ), and their sleep habits/problems were evaluated using the Child and Adolescent Sleep Checklist.ResultsBased on the total difficulties score of the SDQ, the children were divided into two groups: a poor mental health group (n = 76) and a control group (n = 339). In terms of sleep habits, which included total sleep time, bedtime, wake time, and nap conditions, there were no differences between the two groups. Regarding sleep-related problems, however, anxiety before going to sleep (p = 0.026), circadian rhythm abnormalities (p = 0.014), and sleepiness during classes outside of naptimes (p = 0.031) were significantly higher in the poor mental health group than in the control group. Multiple regression analysis showed that poor mental health status was significantly associated with sleepiness and snoring (p = 0.017 and p = 0.018, respectively).ConclusionsThe mental health status of 3–4-year-old children was associated with sleep-related problems, namely sleepiness and snoring. Healthcare providers should pay attention to children’s irregular sleep-wake patterns; moreover, interventions for appropriate sleep hygiene will reduce the psychological burden on both children and their families.

080 Is Napping Only Beneficial to Evening Chronotypes? A Pilot Study

Abstract Introduction Research shows associations between chronotype and behavior. While eveningness is associated with lower levels of self-control, morningness is associated with increased conscientiousness. Additionally, throughout the day, the increase in homeostatic sleep pressure due to wakefulness can affect executive functioning, including emotional regulation. Napping is an effective countermeasure to sleepiness and associated emotional dysregulation, but the impact of chronotype on this benefit is unknown. Therefore, this study aimed to examine the impact of chronotype and a midday nap on an aspect of emotional regulation: frustration tolerance. Methods 40 participants between the ages of 18–50 were randomized into a 60-minute, midday nap or no-nap condition. Chronotype was measured using the Horne-Östberg Morningness-Eveningness Questionnaire (MEQ). Frustration tolerance (FT) was measured pre and post nap using an adaption of Feather’s frustration tolerance task where FT was measured as the time spent on an impossible task. To examine the association of chronotype and FT, correlational analysis was used. Chronotype was also determined using a median split of the MEQ due to few true morning and evening types in the sample. This data was then subjected to a repeated measures ANOVA with condition (pre or post-nap) as a within-subjects factor and group (nap or no-nap; high or low MEQ score) as between-subject factors. Results Results revealed a significant correlation between MEQ score and change in time spent on the impossible task, with those with lower MEQ scores (more evening) showing an increase in time spent on the impossible task, r(20) = -.51, p = .016. Similarly, results of the ANOVA revealed a significant condition (pre or post-nap) by group (nap, no nap; high, low MEQ) interaction, F(1,1) = 4.694, p = .039, such that, those in the nap group with lower MEQ (more evening) spent more time on the impossible task following the nap. Conclusion Our results indicate that chronotype may impact a nap’s positive effect on emotional regulation, with greater benefit for those with the eveningness chronotype. Because napping is currently practiced by 1/3 of American adults, from a personalized medicine perspective, it’s imperative that its chronotype-dependent benefits be investigated further to effectively guide evidence-based recommendations. Support (if any):

Reactive interaction of isopropanol with Co3O4(1 1 1) and Pt/Co3O4(1 1 1) model catalysts

The structure and chemical composition of the catalyst may change under reaction conditions resulting in changes of the active sites and, thereby, loss of selectivity. In this work, we investigated the reactive interaction of isopropanol with well-defined Co3O4(111)/Ir(100) and Pt/Co3O4(111)/Ir(100) model catalysts by means of synchrotron radiation photoelectron spectroscopy (SRPES), near ambient pressure X-ray photoelectron spectroscopy (NAP−XPS), scanning tunneling microscopy (STM), and temperature programmed desorption (TPD). We found that adsorption at 150 K yields molecularly adsorbed isopropanol on both model catalysts accompanied by small fractions of isopropoxide and enolate species on Co3O4(111) and supported Pt nanoparticles, respectively. The reactive interaction of isopropanol-derived species with the model catalysts upon annealing in UHV and in 1×10-7 mbar and 1 mbar of isopropanol results in the reduction of Co3O4(111) followed by its conversion to CoO(111) and, finally, to metallic Co and Pt–Co alloy. The mechanism of isopropanol decomposition reveals remarkable sensitivity to the oxidation state and morphology of the model catalysts. On as-prepared Pt/Co3O4(111) catalyst, Pt particles densely cover the Co3O4(111) substrate steering isopropanol decomposition to acetone and hydrogen. Selective channels towards acetone and propene, both accompanied by water, open after temperature-driven sintering of the supported Pt particles. The selectivity of these channels is controlled by the degree of reduction of the Co3O4(111) substrate and the chemical composition of the supported nanoparticles. At high degrees of reduction of Co3O4(111), the formation of both propene and acetone through selective channels decline due to the strong preference for C–C bond scission. Under NAP conditions, the formation of acetone resumes after complete reduction of model catalysts to metallic Co and Pt–Co alloy.

Naps not as effective as a night of sleep at dissipating sleep pressure.

The two-process model of sleep posits that two processes interact to regulate sleep and wake: a homeostatic (Process S) and a circadian process (Process C). Process S compensates for sleep loss by increasing sleep duration and intensity. Process C gates the timing of sleep/wake favouring sleep during the circadian night in humans. In this study, we examined whether taking six naps throughout a 24-hr period would result in the same amount of dissipation of homeostatic pressure at the end of the day as a night of sleep, when time in bed is equivalent. Data from 46 participants (10-23years; mean=14.5 [± 2.9]; 25 females) were analysed. Slow-wave energy, normalized to account for individual differences in slow-wave activity, was used as a measure of sleep homeostasis. In the nap condition, slow-wave energy of six naps distributed equally during a 24-hr period was calculated. In the baseline condition, slow-wave energy was measured after 9-hr time in bed. A paired t-test was used to compare nap and baseline conditions. A linear regression was used to examine whether slow-wave energy varied as a function of age. Slow-wave energy was greater during baseline than the nap condition (p<.001). No association between age and slow-wave energy was found for baseline or nap conditions. Our findings indicate that multiple naps throughout the day are not as effective at dissipating sleep pressure as a night of sleep. This is likely due to the influence of the circadian system, which staves off sleep during certain times of the day.

The effect of a daytime 60-min nap opportunity on postural control in highly active individuals.

Although napping is commonly used as a strategy to improve numerous physical and cognitive performances, the efficacy of this strategy for improving postural balance has not yet been elucidated. Thus, the aim of this study was to conduct a comprehensive examination of the effect of a 60 min nap opportunity (N60) on different components of postural control. Ten highly active individuals (age = 27 ± 3.5 y, height = 1.75 ± 0.52 m, weight = 66.02 ± 8.63 kg) performed, in a randomized order, two afternoon test sessions following no nap (NN) and N60. Postural balance was assessed using the sensory organisation test (SOT), the unilateral stance test (UST), and the limits of Stability Test performed on NeuroCom® Smart Balance Master. The subjective rating of sleepiness before and after the nap conditions was also assessed. Compared to NN, N60 improved the composite balance score (p < 0.05, ES = 0.75, Δ = 5.3%) and the average and maximum percentage balance in the most challenging postural conditions of the SOT (p < 0.05 for SOT-4 and 5 and p < 0.0005 for SOT-6; ES range between 0.58 and 1.1). This enhanced postural balance in N60 was accompanied with improved visual (p < 0.05; ES = 0.93; Δ = 8.9%) and vestibular (p < 0.05; ES = 0.81; Δ = 10.5%) ratios and a reduced level of sleepiness perception (p < 0.001, ES = 0.87). However, no significant differences were found in any of the UST and LOS components’ scores (p > 0.05). Overall, a 60 min post lunch nap opportunity may be viable for improving static balance, although further work, involving larger samples and more complex motor activities, is warranted.

Memory performance following napping in habitual and non-habitual nappers

Study ObjectivesAfternoon naps benefit memory but this may depend on whether one is a habitual napper (HN; ≥1 nap/week) or non-habitual napper (NN). Here, we investigated whether a nap would benefit HN and NN differently, as well as whether HN would be more adversely affected by nap restriction compared to NN.MethodsForty-six participants in the nap condition (HN-nap: n = 25, NN-nap: n = 21) took a 90-min nap (14:00–15:30 pm) on experimental days while 46 participants in the Wake condition (HN-wake: n = 24, NN-wake: n = 22) remained awake in the afternoon. Memory tasks were administered after the nap to assess short-term topographical memory and long-term memory in the form of picture encoding and factual knowledge learning respectively.ResultsAn afternoon nap boosted picture encoding and factual knowledge learning irrespective of whether one habitually napped (main effects of condition (nap/wake): ps < 0.037). However, we found a significant interaction for the hippocampal-dependent topographical memory task (p = 0.039) wherein a nap, relative to wake, benefitted habitual nappers (HN-nap vs HN-wake: p = 0.003) compared to non-habitual nappers (NN-nap vs. NN-wake: p = 0.918). Notably for this task, habitual nappers’ performance significantly declined if they were not allowed to nap (HN-wake vs NN-wake: p = 0.037).ConclusionsContrary to concerns that napping may be disadvantageous for non-habitual nappers, we found that an afternoon nap was beneficial for long-term memory tasks even if one did not habitually nap. Naps were especially beneficial for habitual nappers performing a short-term topographical memory task, as it restored the decline that would otherwise have been incurred without a nap.Clinical Trial InformationNCT04044885.

Effects of bright light and an afternoon nap on task performance depend on the cognitive domain.

Previous research revealed inconsistent effects of bright light or a short nap at noon on alertness and performance across different tasks. The current study aimed to explore whether the effects of bright light and a short nap at noon on task performance depended on the cognitive domain. Bright light (1,200lx, 4,000K at eye level), nap (near darkness) and control (200lx, 4,000K at eye level) conditions were performed from 1:00 to 1:40PM on three non-consecutive days with a counterbalanced order across participants. After being assigned to one of three conditions, participants underwent two repeated test sessions, each including a psychomotor vigilance task, a go/no-go task, and a paced visual serial addition task, with an interval of more than 1 h, to assess the persistent effects of napping and bright light. Subjective sleepiness, vitality, self-control and mood were also measured. Results showed that accuracy on the go/no-go task and the paced visual serial addition task improved significantly throughout the entire experiment session after napping, whereas reaction speed on the paced visual serial addition task improved time-dependently in the bright light intervention, with a higher reaction speed in only the first test session. Nearly all subjective states benefited from napping but not from bright light. These findings suggested that the effects of bright light and an afternoon nap on task performance would depend on the cognitive domain. An afternoon nap may elicit more effective and persistent benefits on task performance and subjective states.

A daytime nap combined with nighttime sleep promotes learning in toddlers

Napping after learning promotes consolidation of new information during infancy. Yet, whether naps play a similar role during toddlerhood, a stage when many children are beginning to transition away from napping, is less clear. In Experiment 1, we examined whether napping after learning promotes generalization of novel category exemplars 24 h later. Young children (N = 54, age range = 29–36 months) viewed three category exemplars in different contexts from each of three categories and remained awake (No-Nap condition) or napped (Nap condition) after encoding and were then tested 24 h later. Children who napped after learning showed superior generalization 24 h later relative to children who did not nap. In a Nap-Control condition tested 4 h after awakening from a nap, children performed at the same low level as in the No-Nap condition, indicating that generalization stemmed from an additional period of nighttime sleep and not simply from a nap or increased time. In Experiment 2, we examined whether nighttime sleep is sufficient for generalization if it occurs soon after learning. An additional group of children (N = 18) learned before bedtime and were tested 4 h after waking up the next day. Children did not generalize as well as those who had a nap combined with subsequent nighttime sleep. These findings suggest that naps, when combined with a period of nighttime sleep, might help toddlers to retain newly learned information and lead to delayed benefits in generalization.

Effects of a 30 min nap opportunity on cognitive and short-duration high-intensity performances and mood states after a partial sleep deprivation night

ABSTRACT This study evaluated the effects of partial-sleep-deprivation (SDN) and a 30 min nap opportunity on physical and cognitive performances and mood states. Fourteen physically active students (BMI = 232.8 ± 0.4 kg/m2) performed the reaction time, the number cancellation (i.e., assessing vigilance) and the 5-m shuttle run tests and responded to the Profile of Mood States (POMS-f) questionnaire at 18h00 after a normal-sleep (NSN) and a SDN) and after two nap conditions (Nap and no-Nap) realized between 13h00 and 13h30. Vigilance and the reaction time were better after Nap compared to no-Nap opportunity following NSN and SDN and during NSN compared to SDN only during no-Nap. Total and peak distance during the 5-m shuttle run test were higher and the fatigue index was lower during Nap compared to no-Nap condition after NSN and SDN and during NSN compared to SDN during Nap and no-Nnap. Anxiety, fatigue, confusion, and depression were lower and vigour was higher during Nap compared to no-Nap after NSN and SDN and during NSN compared to SDN during Nap and no-Nap. In conclusion, a 30-min of nap opportunity helps to overcome the negative effect of SDN on mood states as well as physical and cognitive performances.

The Effect Of Nap Duration On Sleep Inertia, Muscle Strength, And 3-km Cycling Time Trial Performance

PURPOSE: To determine the impact of napping (15-min and 30-min) on sleep inertia, peak muscle strength, and 3-km cycling time trial performance. METHODS: Six recreationally-trained college-aged participants (Age, 22 ± 1 y; VO2max, 43 ± 12 ml·kg-1·min-1) completed a familiarization- and 3 experimental trials in the afternoon. Following a night of modest sleep restriction (range: 4.6-5.8 h), participants underwent exercise testing without a nap and following 15-min (Nap15) and 30-min (Nap30) naps. Peak isokinetic leg extension force (120 deg·sec-1) and computer-simulated 3-km cycling time trial (TT) performance were assessed 30 min after napping. Sleep inertia was quantified using the Karolinska Sleepiness Scale and the Tower of London cognitive task before and after each nap. Repeated measures ANOVAs were used to assess differences in peak strength and 3-km TT performance between conditions, while a 3 x 2 (nap condition by time) repeated measures ANOVA was used to assess sleep inertia. RESULTS: 3-km TT power output was similar across conditions (no-nap = 212 ± 84 W, Nap15 = 208 ± 95 W; Nap30 = 213 ± 95 W). Though peak strength following Nap30 was not statistically lower than no-nap (p = 0.12), peak strength was 8.0 ± 0.8% lower in Nap30 compared to Nap15 (p < 0.05). Sleep inertia was similar across conditions. CONCLUSION: These data suggest that napping prior to competition will not improve performance but rather may impair peak power-oriented activities. Data should be gathered to assess the impact of longer duration napping and the potential performance benefits of napping following more severe sleep restriction.

0252 Influence of Sleep on Negative Social Judgment

Abstract Introduction Sleep plays an important role in emotional regulation. Emotional regulation can be disrupted by psychosocial stress, including social judgment. It is not known whether sleep can regulate emotions arising from social judgment. The aim of this study is to determine if sleep can reduce emotional reactivity associated with negative social judgment. Methods On day one, subjects participated in a social judgment task (SJT) in the morning, followed by a nap or wake condition. Subjects’ physiological responses to social judgment task (skin conductance and heart rate) and mood were measured before and after the SJT, after the nap/wake condition, and once on day three. Results Mood ratings decreased after social judgment for all subjects, but increased following the nap intervention. Mood ratings improved after the 2 day delay. There were no changes in social status. Skin conductance during judgment decreased for subjects in nap condition, but not wake. After a 2 day delay, skin conductance decreased across subjects, with those in nap condition experiencing greater decrease. Heart rate response during social judgment exposure decreased only for those in nap group, with a 2 day delay showing decreased heart rate response across all subjects. Conclusion A nap directly following social judgment buffers negative response to the experience by decreasing emotional reactivity as measured by mood, skin conductance, and heart rate response. No differences were found between nappers and non-nappers on day three, suggesting that sleep benefits emotional reactivity associated with the stress of social judgment and that these benefits can happen with a nap or a night of sleep, more than a period of wake. Support University of California, Irvine.

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

Abstract 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.

0207 The Effect of Naps on Inhibitory Control and Sustained Attention in Early Childhood

Abstract Introduction Sleep in adults and school-age children has been shown to improve regulatory behaviors. Specifically, slow wave sleep (SWS) disruptions have been positively associated with decreased levels of sustained attention and inhibitory control in adults, while REM sleep has been associated with inhibitory control in typically developing children. However, it is unknown whether midday naps confer a similar benefit in preschool-aged children, particularly since REM sleep is often lacking in their naps. In this study, we used a Go/No-Go task to determine whether SWS during early childhood naps benefits sustained attention and inhibitory control. We also explored nap habituality as a factor given that habitual and non-habitual nappers have different sleep architecture in adults and children. Methods Preschool children (N=22, 38–69 months) completed a Go/No-Go task, after which they either napped with polysomnography (nap condition) or stayed awake (wake condition) for an equivalent amount of time (within subject; order counterbalanced; ~1 week apart). After their nap and wake sessions, they completed the Go/No-Go task again. Results When controlling for nap frequency, participant performance (accuracy) post-session did not differ across conditions. However, by examining only the habitual nappers (5–7 days/week, N=9), we found a moderate positive correlation between percent of sleep spent in SWS and post-nap accuracy (r=0.335, p=0.037). Interestingly, we did not see the same relationship with non-habitual nappers (0–4 days/week, N=13) and found a weak negative correlation with SWS (r=0.007, p=0.031). Conclusion The findings suggest that habitually napping children show a benefit of nap SWS on regulatory behaviors while non-habitual nappers do not. Such results have important translational significance for early education settings. Support NIH R01 HL111695.

0087 Childhood Naps Promote Short-Term Destabilization but Long-Term Consolidation of Emotional Memories

Abstract Introduction Early childhood naps have been shown to support emotional memory consolidation, but this benefit only emerges the following day. It is unknown whether consolidation occurs during the nap itself, or if napping only prepares memories for overnight consolidation. In this study, we used a forced-choice recognition task to determine whether naps protect emotional memories against post-nap interference, which would indicate the occurrence of consolidation. Methods Preschool children (33–67 months; N=63) viewed neutral faces paired with negative or neutral descriptions. Following a nap or an equal interval awake (within-subjects, order counterbalanced, ~1 week apart), half of these participants (N=33) were presented with an interfering set of faces and descriptions, while the other half (N=30) did not receive interference. For all participants, recognition of the original faces was probed after encoding, after the nap or wake interval, and the next morning. Results To assess the influence of napping on changes in emotional memory, 2 (stimulus valence: negative vs. neutral) x 2 (condition: nap vs. wake) repeated-measures ANOVAs were performed. Recall of negative and neutral items did not immediately differ between the nap and wake conditions for the participants who received no interference. 24 hours later, these children trended towards recalling negative and neutral items better if they had napped the previous day (condition main effect: F(1,29)=3.539, p=0.070). In contrast, participants who received interference recalled fewer negative items than neutral items immediately following a nap (p=0.034), while this difference did not emerge following an interval awake. Conclusion Our results suggest that naps initially destabilize emotional memories rather than protecting them against interference. However, this initial destabilization may reflect the partial processing of memories during naps, perhaps allowing for enhanced long-term consolidation. Overall, our findings provide important insight into the mechanism of nap-dependent emotional processing. Support Supported by NIH R01 HL111695 and an Honors Research Grant from Commonwealth Honors College

Exercising before a nap benefits memory better than napping or exercising alone.

Sleep leads to the enhancement of memory, and physical exercise also improves memory along with beneficial effects on sleep quality. Potentially, sleep and exercise may operate independently upon memory; alternatively, they may operate synergistically to boost memory above and beyond exercise or sleep alone. We tested this hypothesis in 115 young healthy adults (23 ± 3.9 years) randomly allocated to one of the four conditions in a 2 (exercise vs. no exercise) × 2 (nap vs. no nap) design. The exercise intervention consisted of a 40-minute, moderate intensity cycling, while the no exercise condition was an equivalent period of rest. This was followed by a learning session in which participants memorized a set of 45 neutral pictures for a later test. Subsequently, participants were exposed to either a 60-minute sleep period (nap) or an equivalent time of resting wakefulness, followed by a visual recognition test. We found a significant interaction between the effects of exercise and nap (p = 0.014, η p2 = 0.053), without significant main effects of exercise or nap conditions. Participants who experienced both exercise plus nap were significantly more accurate (83.8 ± 2.9) than those who only napped (81.1 ± 5.4, p = 0.027) and those who only exercised (78.6 ± 10.3, p = 0.012). Within the combined nap plus exercise group, higher recognition accuracies were associated with higher sleep spindle densities (r = 0.46, p = 0.015). Our results demonstrate that short-term exercise and a nap improve recognition memory over a nap or exercise alone. Exercise and sleep are not independent factors operating separately upon memory but work together to enhance long-term memory.

Does upper-body elevation affect sleepiness and memories of hypnagogic images after short daytime naps?

The present study aimed to examine the effects of a somatosensory stimulus on sleepiness and memories of hypnagogic imagery during short daytime naps. Participants experienced two daytime nap conditions: (1) a somatosensory stimulus was created by raising the upper part of the bed 20min after turning off the light and (2) a somatosensory stimulus was not created; the angle of the upper part of the bed remained flat. Approximately 20min and 30s after turning off the light, participants were awakened and questioned regarding their subjective sleepiness and the presence or absence of hypnagogic imagery. Results showed that subjective sleepiness following the nap was reduced only in the raised condition, and hypnagogic imagery in the raised condition was lower than that in the flat condition. These findings may provide insight on developing new techniques for improving subjective conditions after awakening.