Memory in 3-month-old infants benefits from a short nap.

A broad range of studies demonstrate that sleep has a facilitating role in memory consolidation (see Rasch & Born, ). Whether sleep-dependent memory consolidation is also apparent in infants in their first few months of life has not been investigated. We demonstrate that 3-month-old infants only remember a cartoon face approximately 1.5-2 hours after its first presentation when a period of sleep followed learning. Furthermore, habituation time, that is, the time to become bored with a stimulus shown repetitively, correlated negatively with the density of infant sleep spindles, implying that processing speed is linked to specific electroencephalographic components of sleep. Our findings show that without a short period of sleep infants have problems remembering a newly seen face, that sleep enhances memory consolidation from a very early age, highlighting the importance of napping in infancy, and that infant sleep spindles may be associated with some aspects of cognitive ability.

Frequent daytime naps predict vocabulary growth in early childhood.

BACKGROUND: The facilitating role of sleep for language learning is well-attested in adults and to a lesser extent in infants and toddlers. However, the longitudinal relationship between sleep patterns and early vocabulary development is not well understood. METHODS: This study investigates how measures of sleep are related to the development of vocabulary size in infants and toddlers. Day and night-time sleeping patterns of infants and toddlers were compared with their concurrent and subsequent vocabulary development. Sleep assessments were conducted using a sleep diary specifically designed to facilitate accurate parental report. Sleep measures were used as predictors in a multilevel growth curve analysis of vocabulary development. RESULTS: The number of daytime naps was positively associated with both predicted expressive (p = .062) and receptive vocabulary growth (p = .006), whereas the length of night-time sleep was negatively associated with rate of predicted expressive vocabulary growth (p = .045). Sleep efficiency was also positively associated with both predicted receptive (p = .001) and expressive vocabulary growth (p = .068). CONCLUSIONS: These results point to a longitudinal relationship between sleep and language development, with a particular emphasis on the importance of napping at this age.

Reliability and validity of the Hungarian version of the Pittsburgh Sleep Quality Index (PSQI-HUN): comparing psychiatric patients with control subjects.

PURPOSE: The Pittsburgh Sleep Quality Index is used to evaluate subjective sleep quality, and it is commonly used in clinical research. Subjective sleep quality is also an important clinical measure in patients with psychiatric disorders. The aim of the present study was to evaluate the reliability and validity of the Hungarian version of the Pittsburgh Sleep Quality Index (PSQI-HUN) in both clinical and non-clinical samples. METHODS: The original version of PSQI was translated into Hungarian according to standard guidelines. The PSQI-HUN and the Athens Insomnia Scale (AIS) were subsequently administered to 53 psychiatric patients (schizophrenia, recurrent depressive disorder, mixed anxiety, and depressive disorder) and 178 healthy controls. RESULTS: Internal consistency as measured by Cronbach's alpha in the whole sample was 0.79. Pearson's product-moment correlations between component scores and the global scores were high (0.59-0.88) in the PSQI-HUN indicating the homogeneity of the scale. PSQI-HUN global and component scores differed significantly between psychiatric patients and control subjects. In the psychiatric patient subsample, schizophrenics had lower global scores compared to the other two patient groups. The analysis of convergent validity showed significant correlations between the AIS and the global as well as the component scores of the PSQI-HUN (except the component of sleep latency). CONCLUSIONS: The present study concludes that the PSQI-HUN is a reliable, valid, and standardized measure for assessment of the subjective sleep quality in clinical and research settings.

Napping facilitates word learning in early lexical development.

Little is known about the role that night-time sleep and daytime naps play in early cognitive development. Our aim was to investigate how napping affects word learning in 16-month-olds. Thirty-four typically developing infants were assigned randomly to nap and wake groups. After teaching two novel object-word pairs to infants, we tested their initial performance with an intermodal preferential looking task in which infants are expected to increase their target looking time compared to a distracter after hearing its auditory label. A second test session followed after approximately a 2-h delay. The delay contained sleep for the nap group or no sleep for the wake group. Looking behaviour was measured with an automatic eye-tracker. Vocabulary size was assessed using the Oxford Communicative Development Inventory. A significant interaction between group and session was found in preferential looking towards the target picture. The performance of the nap group increased after the nap, whereas that of the wake group did not change. The gain in performance correlated positively with the expressive vocabulary size in the nap group. These results indicate that daytime napping helps consolidate word learning in infancy.

Electroencephalographic and autonomic alterations in subjects with frequent nightmares during pre-and post-REM periods.

Abnormal arousal processes, sympathetic influences, as well as wake-like alpha activity during sleep were reported as pathophysiological features of Nightmare Disorder. We hypothesized that in Nightmare Disorder, wake-like cortical activity and peripheral measures linked to arousals would be triggered by physiological processes related to the initiation of REM periods. Therefore, we examined electroencephalographic (EEG), motor and autonomous (cardiac) activity in a group of nightmare (NM) and healthy control (CTL) subjects during sleep-state-transitions while controlling for the confounding effects of trait anxiety. Based on the second-nights' polysomnographic recordings of 19 Nightmare Disordered (NM) and 21 control (CTL) subjects, we examined the absolute power spectra focusing on the alpha range, measures of heart rate variability (HRV) and motor (muscle tone) activity during pre-REM and post-REM periods, separately. According to our results, the NM group exhibited increased alpha power during pre-REM, but not in post-REM, or stable, non-transitory periods. While CTL subjects showed increased HRV during pre-REM periods in contrast to post-REM ones, NM subjects did not exhibit such sleep state-specific differences in HRV, but showed more stable values across the examined sleep stages and less overall variability reflecting generally attenuated parasympathetic activity during sleep-state-transitions and during stable, non-transitory NREM states. These differences were not mediated by waking levels of trait anxiety. Moreover, in both groups, significant differences emerged regarding cortical and motor (muscle tone) activity between pre-REM and post-REM conditions, reflecting the heterogeneity of NREM sleep. Our findings indicate that NM subjects' sleep is compromised during NREM-REM transitions, but relatively stabilized after REM periods. The coexistence of sleep-like and wake-like cortical activity in NM subjects seems to be triggered by REM/WAKE promoting neural activity. We propose that increased arousal-related phenomena in NREM-REM transitions might reflect altered emotional processing in NM subjects.

Objective and subjective components of the first-night effect in young nightmare sufferers and healthy participants.

The first-night effect--marked differences between the first- and the second-night sleep spent in a laboratory--is a widely known phenomenon that accounts for the common practice of excluding the first-night sleep from any polysomnographic analysis. The extent to which the first-night effect is present in a participant, as well as its duration (1 or more nights), might have diagnostic value and should account for different protocols used for distinct patient groups. This study investigated the first-night effect on nightmare sufferers (NM; N = 12) and healthy controls (N = 15) using both objective (2-night-long polysomnography) and subjective (Groningen Sleep Quality Scale for the 2 nights spent in the laboratory and 1 regular night spent at home) methods. Differences were found in both the objective (sleep efficiency, wakefulness after sleep onset, sleep latency, Stage-1 duration, Stage-2 duration, slow-wave sleep duration, and REM duration) and subjective (self-rating) variables between the 2 nights and the 2 groups, with a more pronounced first-night effect in the case of the NM group. Furthermore, subjective sleep quality was strongly related to polysomnographic variables and did not differ among 1 regular night spent at home and the second night spent in the laboratory. The importance of these results is discussed from a diagnostic point of view.

Altered sleep in Borderline Personality Disorder in relation to the core dimensions of psychopathology.

The aim of the study was to review the literature regarding sleep disturbances in Borderline Personality Disorder (BPD) and to relate the reported sleep alterations to the underlying core dimensions of BPD pathology. We present a qualitative and theoretical review regarding the empirical studies that investigated objective and subjective sleep quality in BPD and in different psychiatric conditions showing high co-morbidity with this disorder. We show that disturbed sleep including sleep fragmentation, alterations in Slow Wave Sleep and REM sleep, and dysphoric dreaming are prevalent symptoms in BPD. We provide a framework relating the specific sleep alterations to the core dimensions of BPD pathology in order to clarify the inconsistencies of the different findings. The specific sleep disturbances in BPD seem to be related to different dimensions of psychopathological functioning and may have detrimental consequences on waking affect and cognition. Investigating disturbed sleep in BPD in relation to waking symptoms and underlying neural functioning would shed more light on the nature of this complex disorder. Moreover, a stronger emphasis on sleep disturbances would enrich the treatment protocols of BPD.

The Impact of Virtual Reality (VR) on Psychological and Physiological Variables in Children Receiving Chemotherapy: A Pilot Cross-Over Study.

BACKGROUND: Virtual reality (VR) is a novel technology which provides a great opportunity to reduce some of the adverse effects of chemotherapy. OBJECTIVE: Our study aims to investigate the effects of VR on the emotional states of paediatric oncology patients (n = 29, age: 10-18 years) receiving chemotherapy in a clinical setting with a crossover design. METHODS: Children played a VR game in the experimental, and a mobile game in the control condition. Psychological (happiness, joy, fear, nervousness, anxiety, alertness, patience) and physiological variables (heart rate, systolic blood pressure, electrodermal activity), as well as pain and nausea were measured before and after the sessions. Data were analysed with multiple 2-way repeated measures ANOVA. RESULTS: Joy (P = .003) and happiness (P < .001) increased significantly when using VR, while there was no change in the control condition. Anxiety decreased (P = .002) and patience increased (P = .015) in both conditions, implying no additional benefit of VR. Children were more fearful before the VR session (P = .005), which disappeared after it. In case of physiological parameters, electrodermal activity decreased (P = .01) significantly after playing the mobile game, but not after the VR one. CONCLUSIONS: Our investigation point to the positive effects of VR on mood in paediatric oncology inpatients, thus, it could be used as a new tool in improving patients' well-being during chemotherapeutical treatment. Our results indicate that VR is an effective tool in improving patients' well-being during chemotherapeutic treatment.

Impaired executive functions in subjects with frequent nightmares as reflected by performance in different neuropsychological tasks.

Nightmare disorder is a prevalent parasomnia characterized by vivid and highly unpleasant dream experiences during night time sleep. The neural background of disturbed dreaming was proposed to be associated with impaired prefrontal and fronto-limbic functioning during REM sleep. We hypothesized that the impaired prefrontal and fronto-limbic functioning in subjects with frequent nightmares would be reflected at the behavioral level during waking tasks as well. 35-35 Subjects with frequent nightmares and matched controls participated in Study 1, involving an Emotional Go/NoGo, an Emotional Stroop task, and a Verbal Fluency task. Nightmare subjects exhibited longer reaction times in the Emotional Go/NoGo and Emotional Stroop tasks. Moreover, they committed more perseveration errors and showed less fluent word generation in the Verbal Fluency task. Nightmare subjects showed an overall slowing irrespective of the valence of the stimuli. While the effects of sleep quality and waking anxiety were associated to these deficits in some cases, these factors could not solely explain the difference between the two groups. In Study 2, 17 subjects with frequent nightmares and 18 controls were compared by a Color-word and an Emotional, block design Stroop task in order to avoid the slow effects of emotional interference potentially caused by previous items. Nightmare subjects were characterized by an overall slowing in the Emotional Stroop task, irrespective of the valence of the stimuli. In the Color-word Stroop task, nightmare subjects were not significantly slower in comparison with controls. Our results suggest that individuals with frequent nightmares are impaired in executive tasks involving the suppression of task-irrelevant semantic representations.

Disturbed dreaming and sleep quality: altered sleep architecture in subjects with frequent nightmares.

Nightmares are intense, emotionally negative mental experiences that usually occur during late-night sleep and result in abrupt awakenings. Questionnaire-based studies have shown that nightmares are related to impaired sleep quality; however, the polysomnographic profile of nightmare subjects has been only scarcely investigated. We investigated the sleep architecture of 17 individuals with frequent nightmares and 23 control subjects based on polysomnographic recordings of a second night spent in the laboratory after an adaptation night. Nightmare subjects in comparison with control subjects were characterized by impaired sleep architecture, as reflected by reduced sleep efficiency, increased wakefulness, a reduced amount of slow wave sleep, and increased nocturnal awakenings, especially from Stage 2 sleep. While these differences were independent of the effects of waking psychopathology, nightmare subjects also exhibited longer durations of REM sleep that was mediated by heightened negative affect. Our results support that nightmares are related to altered sleep architecture, showing impaired sleep continuity and emotion-related increase in REM propensity.

Different nutritional screening tools and recommended screening algorithm for pediatric oncology patients.

BACKGROUND & AIMS: Cancer is one of the leading causes of death for children; however, appropriate nutritional status can positively affect disease progression and outcome. The aim of this study was to present our self-developed nutritional risk screening method, relate it to another validated tool and to objective bio-impedance measures. We intended to recommend a screening algorithm which can be used in our pediatric oncology facilities. METHODS: We analysed data from 109 pediatric oncology patients (age 3-18) at the 2nd Department of Pediatrics, Semmelweis University between 2017 and 2018. The nutritional status was assessed by the Nutrition screening tool for childhood cancer (SCAN), Nutrition risk screening for pediatric cancer (NRS-PC) our own self-developed screening tool and Bio-impedance analysis (InBody 720 and S10). Classifier properties for low muscle mass measured by Bio-impedance analysis were compared for SCAN and NRS-PC in the overall sample and in the different phases of the disease. RESULTS: The AUC of 0.67 [95% CI:0.58,0.75] of the SCAN was significantly lower (Z = -2.46, p = 0.014) than in the case of the NRS-PC (AUC = 0.75 [95% CI:0.67,0.82]), indicating that NRS-PC has better classifier properties to identify children with lower muscle mass. No significant difference was found in the different phases of the disease. CONCLUSIONS: Based on our results, we suggest screening high BMI patients first with NRS-PC. However, in case of low BMI bio-impedance measures provide more precise information on muscle mass and nutritional risk. Further data are needed to decide whether the NRS-PC is sensitive enough in normal BMI patients.

Sleep is atypical across neurodevelopmental disorders in infants and toddlers: A cross-syndrome study.

This cross-syndrome study focuses on sleep and its relationship with language development. Children with neurodevelopmental disorders present with language delay. Typical language development is constrained by numerous factors including sleep. Sleep is often disrupted in adolescents/adults with neurodevelopmental disorders. We therefore hypothesised that sleep may be disrupted, and correlate with language development, in infants/toddlers with neurodevelopmental disorders. To test our hypothesis, we obtained sleep and vocabulary size data from 75 infants/toddlers with one of three neurodevelopmental disorders (Down syndrome [DS], fragile X syndrome [FXS], Williams syndrome [WS]). Sleep was indeed disrupted in these children. It was also positively associated with receptive vocabulary size in the infants/toddlers with DS and WS (we could not test the relationship between sleep and language in FXS due to lack of power). We argue that disrupted sleep may be a common occurrence in very young children with neurodevelopmental disorders, and it may relate to their ability to acquire their first language.

Spotlight on daytime napping during early childhood.

Daytime napping undergoes a remarkable change in early childhood, and research regarding its relationship to cognitive development has recently accelerated. In this review, we summarize our current understanding of this relationship focusing on children aged <5 years. First, we evaluate different studies on the basis of the experimental design used and the specific cognitive processes they investigate. Second, we analyze how the napping status of children may modulate the relationship between learning and napping. Third, the possible role of sleep spindles, ie, specific electroencephalographic components during sleep, in cognitive development is explored. We conclude that daytime napping is crucial in early memory development.

A Daytime Nap Facilitates Generalization of Word Meanings in Young Toddlers.

STUDY OBJECTIVES: One of the key processes in language development is generalization--the selection and extension of relevant features and information to similar objects and concepts. Little is known about how sleep influences generalization, and studies on the topic are inconclusive. Our aim was to investigate how a nap affects generalization in 16-mo-olds. We hypothesized that a nap is necessary for successful generalization of word meanings. METHODS: Twenty-eight 16-mo-old, typically developing toddlers were randomly assigned to nap and wake groups. We trained toddlers with two novel object-word pairs and tested their initial ability to generalize. Toddlers took part in an intermodal preferential looking task, in which they were shown different colored versions of the original objects and heard one of the trained labels. If toddlers understand the label, they are expected to increase their looking time to the target. Looking behavior was measured with an automated eye tracker. Afterward, the nap group went to sleep, while the wake group stayed awake for approximately 2 h. We then repeated the test of their performance on the generalization task. RESULTS: A significant interaction of group and session was found in preferential looking. The performance of the nap group increased after the nap, whereas that of the wake group did not change. CONCLUSIONS: Our results suggest that napping improves generalization in toddlers.

Disturbed dreaming and the instability of sleep: altered nonrapid eye movement sleep microstructure in individuals with frequent nightmares as revealed by the cyclic alternating pattern.

STUDY OBJECTIVES: Nightmares are disturbing mental experiences during sleep that usually result in abrupt awakenings. Frequent nightmares are associated with poor subjective sleep quality, and recent polysomnographic data suggest that nightmare sufferers exhibit impaired sleep continuity during nonrapid eye movement (NREM) sleep. Because disrupted sleep might be related to abnormal arousal processes, the goal of this study was to examine polysomnographic arousal-related activities in a group of nightmare sufferers and a healthy control group. DESIGN: Sleep microstructure analysis was carried out by scoring the cyclic alternating pattern (CAP) in NREM sleep and the arousal index in rapid eye movement (REM) sleep on the second night of the polysomnographic examination. SETTING: Hospital-based sleep research laboratory. PARTICIPANTS: There were 17 in the nightmare (NMs) group and 23 in the healthy control (CTLs) group. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: The NMs group exhibited reduced amounts of CAP A1 subtype and increased CAP A2 and A3 subtypes, as well as longer duration of CAP A phases in comparison with CTLs. Moreover, these differences remained significant after controlling for the confounding factors of anxious and depressive symptoms. The absolute number and frequency of REM arousals did not differ significantly between the two groups. CONCLUSIONS: The results of our study indicate that NREM sleep microstructure is altered during nonsymptomatic nights of nightmares. Disrupted sleep in the NMs group seems to be related to abnormal arousal processes, specifically an imbalance in sleep-promoting and arousing mechanisms during sleep. CITATION: Simor P; Bódizs R; Horváth K; Ferri R. Disturbed dreaming and the instability of sleep: altered nonrapid eye movement sleep microstructure in individuals with frequent nightmares as revealed by the cyclic alternating pattern. SLEEP 2013;36(3):413-419.

Fluctuations between sleep and wakefulness: wake-like features indicated by increased EEG alpha power during different sleep stages in nightmare disorder.

Although a growing body of research indicates that frequent nightmares are related to impaired sleep regulation, the pathophysiology of nightmare disorder is far from being fully understood. We examined the relative spectral power values for NREM and REM sleep separately in 19 individuals with nightmare disorder and 21 healthy controls, based on polysomnographic recordings of the second nights' laboratory sleep. Nightmare subjects compared to controls exhibited increased relative high alpha (10-14.5Hz) and fronto-central increases in high delta (3-4Hz) power during REM sleep, and a trend of increased fronto-central low alpha (7.75-9Hz) power in NREM sleep. These differences were independent of the confounding effects of waking emotional distress. High REM alpha and low NREM alpha powers were strongly related in nightmare but not in control subjects. The topographical distribution and spectral components of REM alpha activity suggest that nightmare disordered subjects are characterized by wake-like electroencephalographic features during REM sleep.

Is the social brain theory applicable to human individual differences? Relationship between sociability personality dimension and brain size.

Our study intends to examine whether the social brain theory is applicable to human individual differences. According to the social brain theory primates have larger brains as it could be expected from their body sizes due to the adaptation to a more complex social life. Regarding humans there were few studies about the relationship between theory of mind and frontal and temporal brain lobes. We hypothesized that these brain lobes, as well as the whole cerebrum and neocortex are in connection with the Sociability personality dimension that is associated with individuals' social lives. Our findings support this hypothesis as Sociability correlated positively with the examined brain structures if we control the effects of body size differences and age. These results suggest that the social brain theory can be extended to human interindividual differences and they have some implications to personality psychology too.