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Background: Restless sleep is a common complaint in children with sleep and other disorders, when it occurs as an isolated symptom it can depict a separate condition called restless sleep disorder (RSD). A key diagnostic feature of RSD is the polysomnographic (PSG) scoring of five or more large muscle movements (LMM) per hour of sleep. Initial publications on RSD used video-PSG (vPSG) analysis to count LMM. However, recently, scoring criteria for LMM on PSG signals alone have been published, but their correlation with vPSG scoring has not been done. In this study we compare vPSG to PSG scoring of LMM in a group of children with restless sleep., Methods: Video-PSG studies from 20 children (14 boys and six girls, mean age 11.3 years, SD 4.17) were reviewed by a blinded scorer. First, scorer used a video analysis (video-LMM), then on a different day the scorer used PSG criteria for LMM without video (PSG-LMM)., Results: PSG-LMM were found to be significantly more numerous than video-LMM (mean LMM index 8.6 ± 2.95 SD vs. 6.9 ± 2.40 SD, respectively) while their duration was not statistically different (mean LMM duration 11.6 ± 2.33 s vs. 11.6 ± 2.99 s, respectively). 95.4% of video-LMM were also detected by PSG. Both LMM indexes and durations obtained by the two methods correlated significantly between them. A cut off of 6.24 LMM/hour by PSG-LMM was calculated to be equivalent to 5 LMM by video-LMM., Conclusions: PSG-LMM scoring criteria detects >95% of LLM scored by video-PSG. PSG-LMM lead to the detection of a higher number of movements, indicating their higher sensitivity in picking up LMM in PSG recording. This further supports that these criteria need adequate consideration for their eventual inclusion into the current sleep scoring manual. A higher index may be needed to diagnose RSD., Competing Interests: Declaration of competing interest The authors have no financial conflicts of interest to disclose., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Background: A parent survey was conducted to assess the sleep habits of children residing in various countries before and during the SARS-CoV-2 pandemic. It was hypothesized that lockdown would be associated with increased sleep duration., Methods: Outcomes were changes in bedtime, wake time, and sleep duration in the pandemic compared to before. Logistic regression was applied to evaluate the effects of age and covariates on outcomes., Results: A total of 845 questionnaires completed from May 1 to June 10, 2020 were analyzed (45.8% female; age 3-17 years). During the pandemic, 23.1% of preschoolers, 46.2% of school-age children, and 89.8% of adolescents were going to bed after 10 p.m. on weekdays compared to 7.1%, 9.4%, and 57.1% respectively before the pandemic, with these proportions being higher on weekends. Likewise, 42.5% of preschoolers, 61.3% of school-age children, and 81.2% of adolescents were waking after 8 a.m. on weekdays (11.6%, 4.9%, and 10.3%, before) with these proportions being greater on weekends. Sleep duration did not change in 43% of participants on weekdays and in 46.2% on weekends. The 14-17 years group had fourfold increased odds for longer sleep duration on weekdays (p < .01), and children aged 6-13 years had twofold increased odds for longer sleep duration on weekends relative to the 3-5 years age group (p = .01)., Conclusions: Although lockdown was associated with later bedtime and wake time, this shift did not alter sleep duration in more than 40% of children. Yet, compared to preschoolers, high school-aged children were more likely to sleep more on weekdays and primary school children on weekends., (© 2021 Wiley Periodicals LLC.)

Sleep is an essential component of physical and emotional well-being, and lack, or disruption, of sleep due to insomnia is a highly prevalent problem. The interest in complementary and alternative medicines for treating or preventing insomnia has increased recently. Centuries-old herbal treatments, popular for their safety and effectiveness, include valerian, passionflower, lemon balm, lavender, and Californian poppy. These herbal medicines have been shown to reduce sleep latency and increase subjective and objective measures of sleep quality. Research into their molecular components revealed that their sedative and sleep-promoting properties rely on interactions with various neurotransmitter systems in the brain. Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter that plays a major role in controlling different vigilance states. GABA receptors are the targets of many pharmacological treatments for insomnia, such as benzodiazepines. Here, we perform a systematic analysis of studies assessing the mechanisms of action of various herbal medicines on different subtypes of GABA receptors in the context of sleep control. Currently available evidence suggests that herbal extracts may exert some of their hypnotic and anxiolytic activity through interacting with GABA receptors and modulating GABAergic signaling in the brain, but their mechanism of action in the treatment of insomnia is not completely understood.

Sleep is essential for human life. It has different characteristics in the early stages of life compared to later periods: during development, qualitative and quantitative changes in sleep features occur such as the onset of REM/NREM sleep at 3 months, the progressive increase of night sleep duration, and the reduction of total sleep time. Sleep seems to be essential in the cognitive functions' development, especially in the first period of life. Indeed, higher rates of night sleep at the age of 12 and 18 months are associated with higher executive functions' performance. Furthermore, memory consolidation occurs during sleep and sleep contributes to children's learning not only in retaining information but also in organizing memories most efficiently. Therefore, sleep problems could cause negative effects on some features of cognitive development like memory, executive functions, and learning process. There is also an intimate relationship between sleep and regulation of emotional brain functions, with a link between sleep disturbance and behavioral problems., Competing Interests: Financial disclosure The authors have no financial relationships to disclose. Conflicts of interest The authors have no conflicts of interest relevant to this article to disclose., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Objectives: To compare sleep in young children at different obesity risks, which were based on parental weight, as well as to explore the longitudinal associations of sleep characteristics with adiposity., Methods: In total, 107 children from an obesity prevention project were included, of which 43 had normal-weight parents (low obesity risk) and 64 had overweight and/or obese parents (high obesity risk). Sleep was measured yearly from ages 2 to 6 years by using actigraphy. Five sleep characteristics, that of late sleep, long sleep latency, short sleep duration, low sleep efficiency, and irregular sleep onset, were defined and scored across ages, with a higher score indicating more frequent exposure. The outcome variables, also measured yearly, were BMI z score and waist circumference., Results: There was no difference in sleep patterns among children at different risks. Higher short sleep duration score was associated with a greater increase in BMI z score (0.12; 95% confidence interval [CI] 0.01 to 0.25) across ages. Independently of sleep duration, higher late sleep score was associated with greater increases in BMI z score (0.16; 95% CI 0.05 to 0.27) and waist circumference (0.60 cm; 95% CI 0.23 to 0.98). Moreover, compared with children at low risk and without habitual late sleep, children at high risk and with habitual late sleep had greater increases in BMI z score (0.93; 95% CI 0.40 to 1.45) and waist circumference (3.45 cm; 95% CI 1.78 to 5.12)., Conclusions: More frequent exposures to late sleep were associated with greater increases in adiposity measures from ages 2 to 6 years, particularly in children with obese parents., Competing Interests: POTENTIAL CONFLICT OF INTEREST: The authors have indicated they have no potential conflicts of interest to disclose., (Copyright © 2020 by the American Academy of Pediatrics.)

Background: Habitually snoring children are at risk of manifesting disease-related problems even if their sleep studies are overall within normal limits., Study Objectives: To compare sleep spindle activity in children with primary snoring and healthy controls., Methods: Sleep spindle activity including analysis of fast and slow spindles (ie, >13 Hz and <13 Hz, respectively) was evaluated in polysomnographic (PSG) recordings of 20 randomly selected children with primary snoring (PS; normal PSG recordings except for objective presence of snoring; 12 boys, mean age 6.5 ± 2.1 years), and 20 age- and gender-matched PSG-confirmed non-snoring controls., Results: PS children showed significantly lower spindle indices in all non-rapid eye movement (NREM) sleep stages (p < 0.05). In contrast, fast spindles were found in 40% (n = 8) children with PS and in 25% (n = 5) controls. Sleep spindle activity was particularly higher in NREM sleep stage 2 in controls compared PS (76% versus 43% of all marked sleep spindles events in NREM sleep stage 2, p < 0.001)., Conclusions: Children with PS exhibit significantly reduced spindle activity when compared to matched controls. Reduced sleep spindle activity may be an indicator of sleep disruption and, therefore, could be involved in the development of disease-related consequences in snoring children., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Introduction : Sleep disturbances are highly prevalent in children with neurodevelopmental disabilities. Without appropriate treatment, sleep disorders can become chronic and last for many years. However, there are no sleep medications approved by the United States Food and Drug Administration and only one has been approved by the European Medicines Agency for pediatric insomnia; thus, most medications are prescribed off-label. Areas covered : In this narrative review, the authors highlight and summarize the most common drugs and supplements used for the treatment of sleep problems in children with neurodevelopmental disabilities. Recommendations are formulated regarding the use of melatonin and melatonin receptor agonists, sedating antidepressants, antipsychotics, antihistamines, gabapentin, clonidine and orexin receptor antagonists, and benzodiazepines and hypnotic benzodiazepine receptor agonists. Expert opinion : The choice of pharmacological agents and their dosage should be individualized taking into consideration multiple factors, including the severity and type of sleep problem and the associated neurological pathology. Melatonin is widely used and safe in children with neurodevelopmental conditions. Gabapentin, clonidine, trazodone, and mirtazapine hold promise but require further study. Supplements (iron, vitamin D, and 5-hydroxytryptophan) might be helpful. Due to the lack of clinical data, there is still uncertainty concerning dosing regimens and tolerability.

Objective: Changes of sleep architecture have been reported in children with Spinal Muscular Atrophy type 2 (SMA2), mainly represented by a decrease of arousability. No studies have evaluated the effect of long-term ventilation on sleep parameters in these children. The aim of this study was to evaluate the effects of long-term non-invasive positive pressure ventilation (LTNPPV) on sleep architecture and to assess the residual differences from normal controls., Methods: Nine consecutive children with SMA2 underwent two distinct polysomnographic (PSG) studies, one in spontaneous breathing, and subsequently after LTNPPV. The results were then compared to 15 age-matched controls., Results: SMA2 patients showed only slightly modified sleep architecture on LTNPPV: increased stage N2% and decreased number of awakenings, while several significant differences persisted between SMA2 patients on LTNPPV and controls (decreased total sleep time, number of awakenings, sleep efficiency, and percentage of REM sleep). Sleep microstructure, evaluated by means of the Cyclic alternating pattern (CAP) showed only marginal changes on LTNPPV (small shortening of CAP A1 subtype duration and small increase in CAP A3 index). Conversely, CAP parameters on LTNPPV showed significant differences between SMA2 patients vs. controls, with increased A1 subtype percentage and decreased percentage of A2 and A3 subtypes., Conclusions: This is the first study in children affected by SMA2 reporting data on sleep microstructure and their changes after LTNPPV. We found persisting, small but important changes in sleep microstructure during LTNPPV in these children, suggesting that this treatment only partially improves their arousability., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Study Objectives: To evaluate leg movement activity during sleep (LMS) in normal school-age children and adolescents, to eventually establish age-specific periodic LMS (PLMS) index thresholds that support the diagnosis of restless legs syndrome (RLS), and to evaluate the utility of other LMS indices., Methods: Polysomnographic recordings from 61 controls, 46 children with RLS, and 44 children with narcolepsy type 1 (NT1) were analyzed for total leg movements (LMS), PLMS, and isolated leg movements (ISOLMS) duration and indices, separately for school-age children and adolescents. Moreover, intermovement interval (IMI) graphs and time-of-night distribution of LMS were analyzed, and cut-off thresholds for PLMS index and total LMS index were assessed for the separation of RLS from controls., Results: All indices tended to decrease from school-age children to adolescents in normal controls and in NT1, whereas in RLS, only PLMS index increased. All school-age children had a similar IMI distribution with a single peak at IMI 2-4 s followed by gradual decline. In adolescents with RLS, a second peak at IMI 10-50 s was seen. Time-of-night distribution of most indices decreased in RLS, whereas most tended to increase in NT1. A PLMS index cutoff of 2 per hour best differentiated RLS from controls in school-age children (accuracy 70.0%) and in adolescents (accuracy 70.8%); however, most participants with NT1 also showed PLMS indices higher than this threshold., Conclusions: PLMS index alone does not reliably predict the diagnosis of RLS in children and adolescents. However, analyses of IMI distribution and time-of-night distribution provide additional elements to support a diagnosis of RLS.

Periodic leg movements during sleep (PLMS) are sequences of ≥4 motor events with intermovement intervals (IMI) of 10-90 s. PLMS are a supportive diagnostic criterion for restless legs syndrome (RLS) and entail cardiac activation, particularly when associated with arousal. RLS patients also over-express short-interval leg movements during sleep (SILMS), which have IMI <10 s and are organized mainly in sequences of two movements (doublets). We tested whether the cardiac activation associated with SILMS doublets differs from that associated with PLMS in a sample of 25 RLS patients. We analysed time-series of R-R intervals synchronized to the onset of SILMS doublets or PLMS that entailed an arousal during non-rapid eye movement (NREM) sleep. We assessed cardiac activation based on the R-R interval decrease with respect to baseline during NREM sleep without leg movements. We found that the duration of the R-R interval decrease with SILMS doublets was significantly longer than that with PLMS, whereas the maximal decrease in R-R interval was similar. Scoring SILMS in RLS patients may therefore be relevant from a cardiac autonomic perspective., (© 2017 European Sleep Research Society.)

Study Objectives: We aimed to compare 2-year-old children born preterm with children born full term regarding: (1) sleep characteristics, (2) temperament, and (3) relations between sleep pattern and habits and temperament., Methods: The study included 51 preterm children with normal cognitive, language, and motor development (mean = 20.94 months, standard deviation [SD] = 4.08) and 57 full-term children (mean = 21.19, SD = 4.32). To assess sleep-related difficulties and habits and child temperament, mothers completed the following questionnaires: the (1) Sleep Disturbance Scale for Children-adapted (SDSC); (2) Brief Infant Sleep Questionnaire (BISQ); and (3) Italian Temperament Questionnaires-version 12-36 months (QUIT)., Results: Preterm children needed less support to fall asleep and fell asleep more often alone in their own bed compared to those born at full term; however, preterm children showed more frequent sleep difficulties, such as restlessness and breathing problems during the night. In addition, preterm children had lower scores in the temperamental dimension of attention and higher scores in negative emotionality than full-term children. Finally, sleep problems were correlated with higher motor activity, lower social orientation and attention, and increased negative emotionality; a shorter nocturnal sleep duration was related to higher motor activity and lower inhibition to novelty whereas an earlier rise time was associated with lower attention and social orientation., Conclusions: Preterm children showed sleep pattern problems and disturbance, predominance of attention problems, and negative emotionality related to sleep disruption., (© 2017 American Academy of Sleep Medicine)

The aim of this study was to define the time structure of leg movements during sleep occurring with an intermovement interval (onset-to-onset) shorter than 10 s in patients with restless legs syndrome and controls, and to compare it to the structure of movements with intervals of 10-90 s or >90 s. Polysomnographic recordings of 141 untreated patients and 68 age-matched normal controls were analysed. All movements were detected and classified into three categories, separated by intervals of <10, 10-90 or >90 s. The number of movements included in each category was significantly higher in patients than in controls. The movements with an interval of >90 s occurred steadily during the night, whereas the hourly distribution of movements with intervals of <10 or 10-90 s was decreasing or bell-shaped in patients or controls, respectively. Movements with an interval of <10 s tended to have a shorter duration and constituted shorter sequences than movements with intervals of 10-90 or >90 s. The time structure features of the three categories of movements considered in this study were found to be clearly different. This, together with previous observations on the differential effects of dopamine agonists on movements with different intervals, suggests that movements with intervals of <10 and >90 s are regulated by neurotransmitter mechanisms different from those modulating movements with an interval of 10-90 s., (© 2017 European Sleep Research Society.)

A coherent body of evidence supports the notion that sleep is a local and use-dependent process. Significant changes in brain morphology and function occur in the first years of life, revealing a postero-anterior trajectory of cortical maturation. On this basis, a recent study demonstrated that regional cortical maturation between early childhood and late adolescence is reflected in regional changes of sleep slow wave activity (SWA) during non-rapid eye movement (NREM) sleep. Our hypothesis is that changes of electroencephalogram (EEG) rhythms during sleep from birth to childhood are also mirrored by parallel regional changes in the EEG rhythms of sleep according to the assumption of a postero-anterior gradient in cortical maturation. We studied all-night EEG of 39 healthy, full-term, infants and children aged between 0 and 48 months, evaluating regional differences in NREM sleep. We confirmed the strictly local nature of sleep with frequency-specific regional differences. Specifically, we found a general shift of maxima of the upper alpha activity from occipital to prefrontal regions, expressed mainly by the ~11 Hz frequency. This shift corresponds to a postero-anterior trajectory of the so-called 'slow spindles'. The theta and alpha EEG activity of the frontal cortex exhibits a clear, positive, correlation with age. We conclude that specific local differences during NREM sleep, parallel cortical maturation also in the first 4 years of life., (© 2016 European Sleep Research Society.)

Study Objectives: Pediatric type 1 narcolepsy is often challenging to diagnose and remains largely undiagnosed. Excessive daytime sleepiness, disrupted nocturnal sleep, and a peculiar phenotype of cataplexy are the prominent features. The knowledge available about the regulation of circadian rhythms in affected children is scarce. This study compared circadian rest-activity rhythm and actigraphic estimated sleep measures of children with type 1 narcolepsy versus healthy controls., Methods: Twenty-two drug-naïve type 1 narcolepsy children and 21 age- and sex- matched controls were monitored for seven days during the school week by actigraphy. Circadian activity rhythms were analyzed through functional linear modeling; nocturnal and diurnal sleep measures were estimated from activity using a validated algorithm., Results: Children with type 1 narcolepsy presented an altered rest-activity rhythm characterized by enhanced motor activity throughout the night and blunted activity in the first afternoon. No difference was found between children with type 1 narcolepsy and controls in the timing of the circadian phase. Actigraphic sleep measures showed good discriminant capabilities in assessing type 1 narcolepsy nycthemeral disruption., Conclusions: Actigraphy reliably renders the nycthemeral disruption typical of narcolepsy type 1 in drug-naïve children with recent disease onset, indicating the sensibility of actigraphic assessment in the diagnostic work-up of childhood narcolepsy type 1., (© 2016 Associated Professional Sleep Societies, LLC.)

Objective: To evaluate the diagnostic accuracy of the standard periodic leg movement during sleep (PLMS) index, a recently introduced alternative one, and the periodicity index (PI) for restless legs syndrome (RLS)., Subjects and Methods: A total of 107 patients with RLS were retrospectively identified and included (47 males and 60 females, mean age 56.9 years), along with 48 normal controls (24 males and 24 females, mean age 52.0 years). The standard PLMS index, the alternative PLMS index, and the PI were calculated from polysomnographic recordings. In order to establish the best performing threshold for the diagnosis of RLS, sensitivity and specificity were calculated with a series of threshold values ranging from 5 to 20/hour for the two PLMS indices, and from 0.2 to 0.9 for the PI., Results: The optimal threshold was found to be between 15 and 16/hour for the standard PLMS index, close to 13/hour for the alternative index, and around 0.5 for the periodicity index. With these thresholds, all methods showed high values of sensitivity and specificity, with corresponding high positive and negative predictive values and accuracy; the receiver operating characteristic (ROC) curve areas were similar, and the Kappa coefficient of agreement indicated a 'very good' agreement between the PLMS indices., Conclusions: This study assessed the cut-off values of the standard (15-16/hour) and alternative (13/hour) PLMS indices, and of the PI (0.5). The diagnostic accuracy of all indices for RLS vs controls was found to be acceptably high, with the new alternative PLMS index performing slightly higher than the other two indices., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Objectives: We aimed to investigate the impact of different habits concerning television (TV) use and the time of day in which TV is watched on the sleep quality of young children., Methods: Parents of 100 healthy children (58% boys, mean age of 2.7 ± 1.5 years) attending a routine health check completed the Sleep Disturbance Scale for Children (SDSC) and a questionnaire concerning TV and electronic media use. Children were divided into those with a normal (SDSC-) or abnormal (SDSC+) questionnaire score. TV viewing habits were compared between groups., Results: The total sleep time and total TV viewing time were not different between groups. A TV set was inside each child's bedroom in 51% of participants. Children with a TV in their bedroom showed significantly higher scores in the "sleep terrors," "nightmares," "sleep talking," and "tired when waking up" responses of the SDSC (P = 0.02, 0.01, 0.01, and 0.01, respectively). Children with a TV in their room had an odds ratio (95% confidence interval) of 3.29 (1.08-9.99) for having an abnormal SDSC. Evening TV viewers had significantly higher SDSC scores compared with those who watched TV earlier during the day (P = 0.04)., Conclusions: The presence of a TV set in the child's bedroom was associated with significant reductions in the quality of young children's sleep. Evening exposure to TV was associated with significantly worse sleep quality., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Study Objectives: The aim of this study was to describe and analyze the association between bilateral leg movements (LMs) during sleep in subjects with restless legs syndrome (RLS), in order to eventually support or challenge the current scoring rules defining bilateral LMs., Methods: Polysomnographic recordings of 100 untreated patients with RLS (57 women and 43 males, mean age 57 y) were included. In each recording, we selected as reference all LMs that occurred during sleep and that were separated from another ipsilateral LM by at least 10 sec of EMG inactivity. For each reference LM and an evaluation interval from 5 sec before the onset to 5 sec after the offset of the reference LM, we evaluated (1) the presence or absence of contralateral leg movement activity and (2) the distribution of the onset-to-onset and (3) the offset-to-onset differences between bilateral LMs., Results: We selected a mean of 368 (± 222 standard deviation [SD]) reference LMs per subject. For 42% (± 22%) of the reference LMs no contralateral leg movement activity was observed within the evaluation interval. In 55% (± 22%) exactly one and in 3% (± 2%) more than one contralateral LM was observed. A further evaluation of events where exactly one contralateral LM was observed showed that in most (1) the two LMs were overlapping (93% ± 9% SD) and (2) were classified as bilateral according to the World Association of Sleep Medicine and the International Restless Legs Syndrome Study Group (WASM/ IRLSSG) (96% ± 6% SD) and (3) the American Academy of Sleep Medicine scoring rules (99% ± 2% SD). Although there was a systematic and statistically significant difference in standard LM indices during sleep based on the two different definitions of bilateral LMs, the size of the difference was not clinically meaningful (maximum individual, absolute difference in LM indices ± 2.5). In addition, we found that the duration of LMs within bilateral LM pairs was longer compared to monolateral LMs and that the duration of the single LMs in bilateral LM pairs tended to correlate., Conclusions: The results of this study indicate that the two current standard scoring rules for the definition of bilateral LMs during sleep provide largely corresponding classifications in subjects with RLS and, in a clinical context, can be considered to be equivalent., (© 2016 Associated Professional Sleep Societies, LLC.)

Study Objectives: The purpose of this study was to analyze differences between preadolescents and adolescents on the use of technology and to test the contribution of using Internet and mobile phone, and circadian preference on sleep quality., Methods: We recruited a sample of 850 (364 males) preadolescents and adolescents. Self-report questionnaires about sleep schedule, sleep wake behavior problems, circadian preferences, and the use of technology (e.g., Internet and mobile phone) were administered. Students were asked to fill out the School Sleep Habits Survey, a self-report questionnaire on the use of technology, the Mobile Phone Involvement Questionnaire (MPIQ), and the Shorter Promis Questionnaire (SPQ)., Results: Adolescents reported more sleep problems, a tendency toward eveningness, and an increase of Internet and phone activities, as well as social network activities, while preadolescents were more involved in gaming console and television viewing. The regression analysis performed separately in the two age groups showed that sleep quality was affected by the circadian preference (eveningness) in both groups. Adolescents' bad sleep quality was consistently associated with the mobile phone use and number of devices in the bedroom, while in preadolescents, with Internet use and turning-off time., Conclusions: The evening circadian preference, mobile phone and Internet use, numbers of other activities after 21:00, late turning off time, and number of devices in the bedroom have different negative influence on sleep quality in preadolescents and adolescents., (© 2015 American Academy of Sleep Medicine.)

Study Objectives: To analyze statistically the association between periodic leg movements during sleep (PLMS) and arousals, in order to eventually support or challenge the current scoring rules and to further understand their reciprocal influence., Setting: Sleep research center., Patients: Twenty untreated consecutive patients with restless legs syndrome (RLS) (13 women and 7 males, mean age 60.9 y)., Methods: In each recording, we selected all PLMS/arousal pairs that met the following inclusion criteria: (a) PLMS events that were separated from another PLMS event (preceding or following) by at least 10 s of EMG inactivity; (b) arousal events separated from another arousal event (preceding or following) by at least 10 s of stable EEG baseline activity; (c) PLMS/arousal pairs were then selected among events identified according to the previous two criteria, when PLMS and arousals were separated (offset-to-onset) by no more than 10 s, regardless of which was first., Measurements and Results: We selected a mean of 46.1 (SD 25.55) PLMS/arousal pairs per subject; in these pairs, average PLMS duration was 3.2 s (0.65) and average arousal duration was 6.5 s (0.92). Within these event pairs, the great majority (on average 98.4%, SD 3.88) was separated by less than 0.5 s (i.e., between the end of one event and the onset of the other, regardless of which was first). Arousal onsets preceded PLMS onset in 41.2% of pairs, while the opposite was true for the remaining 58.8% of pairs. A significant correlation between PLMS duration and arousal duration was also found (r = 0.447, P < 0.000001)., Conclusion: The results of this study support the current rule for the definition of the association between periodic leg movements during sleep (PLMS) and arousals. The tight time relationship between PLMS and arousals and their correlated durations seem to indicate that both events might be regulated by a complex mechanism, rather than being connected by a simple reciprocal cause/effect relationship., (© 2015 Associated Professional Sleep Societies, LLC.)

Background/purpose: Melatonin, an indoleamine secreted by the pineal gland, plays a key role in regulating circadian rhythm. It has chronobiotic, antioxidant, anti-inflammatory and free radical scavenging properties., Methods: A conference in Rome in 2014 aimed to establish consensus on the roles of melatonin in children and on treatment guidelines., Results and Conclusion: The best evidence for efficacy is in sleep onset insomnia and delayed sleep phase syndrome. It is most effective when administered 3-5 h before physiological dim light melatonin onset. There is no evidence that extended-release melatonin confers advantage over immediate release. Many children with developmental disorders, such as autism spectrum disorder, attention-deficit/hyperactivity disorder and intellectual disability have sleep disturbance and can benefit from melatonin treatment. Melatonin decreases sleep onset latency and increases total sleep time but does not decrease night awakenings. Decreased CYP 1A2 activity, genetically determined or from concomitant medication, can slow metabolism, with loss of variation in melatonin level and loss of effect. Decreasing the dose can remedy this. Animal work and limited human data suggest that melatonin does not exacerbate seizures and might decrease them. Melatonin has been used successfully in treating headache. Animal work has confirmed a neuroprotective effect of melatonin, suggesting a role in minimising neuronal damage from birth asphyxia; results from human studies are awaited. Melatonin can also be of value in the performance of sleep EEGs and as sedation for brainstem auditory evoked potential assessments. No serious adverse effects of melatonin in humans have been identified., (Copyright © 2014 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.)

Study Objectives: To longitudinally examine sleep patterns, habits, and parent-reported sleep problems during the first year of life., Methods: Seven hundred four parent/child pairs participated in a longitudinal cohort study. Structured interview recording general demographic data, feeding habits, intercurrent diseases, family history, sleep habits, and parental evaluation of the infant's sleep carried out at 1, 3, 6, 9, and 12 months., Results: Nocturnal, daytime, and total sleep duration showed a high inter-individual variability in the first year of life associated with changes in the first 6 months and stability from 6 to 12 months. Bedtime was at around 22:00 and remained stable at 6, 9, and 12 months of age. Approximately 20% of the infants had more than 2 awakenings and slept more often in the parent bed. Nearly 10% of the infants were considered as having a problematic sleep by parents and this significantly correlated with nocturnal awakenings and difficulties falling asleep., Conclusions: Sleep patterns change during the first year of life but most sleep variables (i.e., sleep latency and duration) show little variation from 6 to 12 months. Our data provide a context for clinicians to discuss sleep issues with parents and suggest that prevention efforts should focus to the first 3-6 months, since sleep patterns show stability from that time point to 12 months.

Objective: To analyze the acute effects of sodium oxybate (SO) on polysomnographic night-time recordings (PSG) and multiple sleep latency test (MSLT) on patients with narcolepsy with cataplexy (NC)., Methods: Sixteen NC adult patients were recruited, together with 16 normal controls. Two consecutive PSG followed by two MSLT sessions were carried out, before and during the first night of SO assumption, respectively., Results: The administration of SO was followed by a significant decrease in number of stage shifts and awakenings, wakefulness after sleep onset, and percentage of sleep stage 1. Sleep efficiency and slow wave sleep percentage increased. REM latency decreased significantly from 73 to 12 min. Cyclic alternating pattern (CAP) rate remained unchanged but the percentage of CAP A3 subtypes decreased. The number of CAP A3 subtypes per hour of NREM sleep decreased significantly, whereas that of A1 remained unchanged. The duration of A1 and A3 subtypes was slightly increased. Chin muscle tone was not modified by SO as well as periodic leg movements during sleep, but their periodicity index decreased, becoming similar to that of controls. MSLT sleep latency also significantly improved after SO intake., Conclusions: The administration of SO in NC patients is followed by immediate important and complex effects on PSG parameters and MSLT, including an evident (over)increase in slow wave sleep, which does not display a physiological microstructure, a moderate decrease in periodic and isolated LMs, possibly mediated by a disinhibited dopaminergic neuronal activity, and an improvement on daytime mean sleep latency at the MSLT., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background: The existence of a correlation and/or comorbidity between sleep disorders and headache, related to common anatomical structures and neurochemical processes, has important implications for the treatment of both conditions., Methods: The high prevalence of certain sleep disorders in children with migraine and the fact that sleep is disrupted in these patients highlight the importance of a specific therapy targeted to improve both conditions., Findings: The treatment of sleep disorders like insomnia, sleep apnea, sleep bruxism and restless legs syndrome, either with behavioral or pharmacological approach, often leads to an improvement of migraine. Drugs like serotoninergic and dopaminergic compounds are commonly used for sleep disorders and for migraine prophylaxis and treatment: Insomnia, sleep-wake transition disorders and migraine have been related to the serotonergic system abnormality; on the other hand prodromal symptoms of migraine (yawning, drowsiness, irritability, mood changes, hyperactivity) support a direct role for the dopaminergic system that is also involved in sleep-related movement disorders., Conclusions: Our review of the literature revealed that, beside pharmacological treatment, child education and lifestyle modification including sleep hygiene could play a significant role in overall success of the treatment. Therefore comorbid sleep conditions should be always screened in children with migraine in order to improve patient management and to choose the most appropriate treatment., (© International Headache Society 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.)

Study Objectives: To analyze the electroencephalographic (EEG) spectral content in untreated patients with restless legs syndrome (RLS) during the sleep onset period (SOP) and during the quiet wakefulness preceding sleep, in order to test the hypothesis that a state of hyperarousal might be present during the SOP with RLS., Setting: Sleep Research Centre., Patients: Twenty-seven untreated consecutive patients with RLS (mean age = 53.6 y), 11 untreated consecutive patients with primary insomnia (mean age = 58.9 y), and 14 normal controls (mean age = 50.3 y)., Methods: SOP was defined as the 10-min period centered with the occurrence of the first sleep spindle in the EEG, and then subdivided into SOP-1 (period of 5 min before the first spindle) and SOP-2 (period of 5 min following). Leg movements occurring during SOP were counted and used as a covariate in the statistical analysis. Also, one period of 1 min of artifact-free quiet wakefulness after lights off was identified. EEG spectral analysis was run during these periods using the C3/A2 or C4/A1 channel., Measurements and Results: Increased EEG alpha and beta bands and/or beta/delta ratio in RLS versus normal controls, during both wakefulness preceding sleep and SOP (both parts SOP-1 and SOP-2) were found, which were, however, smaller than the increases found in patients with insomnia., Conclusion: The results of this study support the hypothesis of the presence of a state of hyperarousal in restless legs syndrome (RLS) during the sleep onset period. Treatment for RLS might need to take these findings into consideration., Citation: Ferri R, Cosentino FI, Manconi M, Rundo F, Bruni O, Zucconi M. Increased electroencephalographic high frequencies during the sleep onset period in patients with restless legs syndrome.

Objectives: To evaluate the leg movement (LM) time structure (periodicity and night distribution) during sleep in children with attention-deficit/hyperactivity disorder (ADHD) and their eventual changes after treatment with levodopa (L-DOPA)., Subjects and Methods: One group of ADHD patients (n=18) and another group of normal controls (n=17) were recruited; those with ADHD were randomized to L-DOPA or placebo therapy. At baseline (both groups) and after therapy (only patients) subjects underwent full-night polysomnography (PSG) and the leg motor pattern was evaluated with advanced tools of analysis particularly able to detect and describe LM time structure (periodicity and distribution)., Results: With respect to controls ADHD children showed prolonged sleep latency, increased number of stage shifts, awakenings, and percentage of sleep stage 1. Arousal index was higher in ADHD and also their PLMS index was slightly but considerably higher than controls; however, their periodicity was low and not different from controls. Only sleep latency was significantly reduced by L-DOPA treatment with all the other parameters (sleep scoring and LM activity) remaining substantially unmodified., Conclusions: LMs during sleep in children with ADHD do not show a highly periodic character and are not considerably modified by L-DOPA treatment; this finding has potential implications for drug treatment that might target the most prominent changes observed in our study including arousals and sleep structure disruption., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Preliminary evidence suggests a possible association between Attention-Deficit/Hyperactivity Disorder and Restless Legs Syndrome with or without Periodic Limb Movements during Sleep. When comorbid, Restless Legs Syndrome/Periodic Limb Movements during Sleep might aggravate Attention-Deficit/Hyperactivity Disorder symptoms. Pharmacological treatment of Attention-Deficit/Hyperactivity Disorder may be associated, at least in some cases, with adverse cardiovascular events, including clinically significant elevation in heart rate and systemic blood pressure. However, the characteristics of patients with Attention-Deficit/Hyperactivity Disorder at risk for cardiovascular events during pharmacological treatment are poorly understood. Here, we hypothesize that Restless Legs Syndrome and/or Periodic Limb Movements during Sleep comorbid with Attention-Deficit/Hyperactivity Disorder increase cardiovascular risk via imbalance in activity of the autonomic nervous system. Such an imbalance of the could be related to alterations of sleep microarchitecture also detected by cyclic alternating pattern analysis. If empirical studies confirm our hypothesis, the clinician would be advised to systematically screen for and effectively treat Restless Legs Syndrome/Periodic Limb Movements during Sleep even before starting treatment with Attention-Deficit/Hyperactivity Disorder drugs. The management of Restless Legs Syndrome/Periodic Limb Movements during Sleep might reduce cardiovascular risk during pharmacological treatment of Attention-Deficit/Hyperactivity Disorder., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Objective: The aims of this study were to evaluate the sleep habits of children with drug resistant epilepsy and to correlate sleep abnormalities with epilepsy and level of intelligence., Subjects and Methods: Twenty five subjects with drug resistant epilepsy (14 males, age range 2-16.4 years) were recruited for this study. A control group was formed by 23 normal children. Two instruments to assess sleep habits were administered to the patients with epilepsy: a questionnaire on sleep habits (to preschool children) and a questionnaire on sleep behavior (for children aged more than seven years old); a cognitive test (Wechsler Intelligence Scale for Children-WISC) was also performed. Patients underwent a complete polysomnographic study and sleep parameters, including CAP, were analyzed and correlated according to cognitive-behavioral measures in children with epilepsy., Results: Children with drug-resistant epilepsy and severe mental retardation showed sleep abnormalities such as low sleep efficiency, high percentage of wakefulness after sleep onset, reduced slow wave sleep, and reduced REM sleep. Sleep microstructure evaluated by means of CAP analysis showed a decrease in A1 index during N3 in patients with more severe cognitive impairment. Children with epilepsy and cognitive impairment (n=10) had higher Sleep Behavior Questionnaire for Children (SBQC) total scores (65.60 ± 18.56) compared to children with epilepsy and normal IQ (50.00 ± 10.40), p<0.05., Conclusions: Children with drug-resistant epilepsy have a greater incidence of sleep problems regarding qualitative aspects, macrostructure, and CAP. The decrease of CAP rate and of A1, mainly during slow wave sleep (associated to REM sleep reduction), might represent a sleep microstructural pattern of intellectual disability., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Objective: Children with GH deficiency (GHD) show a general decrease in electroencephalographic (EEG) arousability represented by a significant global decrease in Cyclic Alternating Pattern (CAP). The aim of the present study was to evaluate if sleep structure is influenced by GH substitutive therapy by analyzing the classical sleep architecture parameters and sleep microstructure by means of CAP., Subjects and Methods: Laboratory polysomnographic sleep recordings were obtained from five children affected by GHD (two girls and three boys; mean age: 4.6 ± 3.1 years), at baseline and after GH therapy, and from 10 normal healthy children (four girls and six boys, mean age: 5.6 ± 2.2 years)., Results: Compared to controls, GHD subjects showed a reduced total sleep time with increased wakefulness and a consequent decrease in sleep efficiency; GH therapy was associated with an increase of the awakenings/hour and a large effect size was evident for sleep latency, sleep efficiency, and stage N3, which were decreased, and for stage W, which was increased. CAP appeared to be globally reduced and all phase A subtypes and CAP cycle showed a longer duration in GHD children vs. controls. GH substitutive treatment was followed by an increase in CAP rate (total, in N2, and in N3); additionally, A1 index was also significantly increased, especially during stage N3, with a very large effect size. On the other hand, A2 and A3 index and CAP cycle mean duration were reduced., Conclusion: Sleep stage architecture seems to be influenced by the GH status, but the analysis of sleep microstructure by means of CAP reveals an enhancement of EEG slow oscillations in GHD patients (demonstrated by an increase in CAP rate and A1 index during N3) after the start of GH replacement therapy. These findings deserve to be verified in a larger trial., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Cyclic alternating pattern CAP is the EEG marker of unstable sleep, a concept which is poorly appreciated among the metrics of sleep physiology. Besides, duration, depth and continuity, sleep restorative properties depend on the capacity of the brain to create periods of sustained stable sleep. This issue is not confined only to the EEG activities but reverberates upon the ongoing autonomic activity and behavioral functions, which are mutually entrained in a synchronized oscillation. CAP can be identified both in adult and children sleep and therefore represents a sensitive tool for the investigation of sleep disorders across the lifespan. The present review illustrates the story of CAP in the last 25 years, the standardized scoring criteria, the basic physiological properties and how the dimension of sleep instability has provided new insight into pathophysiolology and management of sleep disorders., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Background/aims: Growth hormone (GH) is preferentially secreted during slow wave sleep and the interactions between human sleep and the somatotropic system are well documented, although only few studies have investigated the sleep EEG in children with GH deficiency (GHD). The aim of this study was to evaluate the sleep structure of children with dysregulation of the GH/insulin-like growth factor axis., Methods: Laboratory polysomnographic sleep recordings were obtained from 10 GHD children and 20 normal healthy age-matched children. The classical sleep parameters were evaluated together with sleep microstructure, by means of the cyclic alternating pattern (CAP), in GHD patients and compared to the control group., Results: GHD children showed a significant decrease in total sleep time, sleep efficiency, movement time and in non-rapid eye movement sleep stage 2. Although some indicators of sleep fragmentation were increased in GHD children, we found a general decrease in EEG arousability represented by a significant global decrease in the CAP rate, involving all CAP A phase subtypes., Conclusions: The analysis of sleep microstructure by means of CAP, in children with GHD, showed a reduction of transient EEG amplitude oscillations. Further studies are needed in order to better clarify whether GH therapy is able to modify sleep microstructure in GHD children, and the relationships between sleep microstructure, hormonal secretion and neurocognitive function in these patients., (Copyright © 2011 S. Karger AG, Basel.)

Aim: The purpose of this review was to examine the possible pathophysiological links between epilepsy, cognition, sleep macro- and microstructure, and sleep disorders to highlight the contributions and interactions of sleep and epilepsy on cognitive functioning in children with epilepsy., Method: PubMed was used as the medical database source. No language restriction was placed on the literature searches, and citations of relevant studies in the paediatric age range (0-18 y) were checked. Studies including a mixed population but with a high percentage of children were also considered., Results: The searches identified 223 studies. One reviewer scanned these to eliminate obviously irrelevant studies. Three reviewers scanned the remaining 128 studies and their relevant citations. The review showed that several factors could account for the learning impairment in children with epilepsy: aetiology, electroencephalographic (EEG) discharges, and persistence and circadian distribution of seizures, etc. EEG discharges may affect cognition and sleep, even in the absence of clinical or subclinical seizures. The sleep deprivation and/or sleep disruption affect the neurophysiological and neurochemical mechanisms important for the memory-learning process, but also influence the expression of EEG discharges and seizures. Learning and memory consolidation can take place over extended periods, and sleep has been demonstrated to play a fundamental role in these processes through neuroplastic remodelling of neural networks. Epilepsy and EEG paroxysms may affect sleep structure, interfering with these physiological functions., Interpretation: Improvement in the long-term cognitive-behavioural prognosis of children with epilepsy requires both good sleep quality and good seizure control. The antiepileptic drug of choice should be the one that interferes least with sleep structure and has the best effect on sleep architecture--thus normalizing sleep instability, especially during non-rapid eye movement sleep.

Study Objectives: To analyze cyclic alternating pattern (CAP) in restless legs syndrome (RLS) and the eventual changes induced by the acute administration of pramipexole., Setting: Sleep clinic in a scientific research institute., Interventions: Placebo or pramipexole 0.25 mg., Methods: Thirty-four patients were included: 19 patients received 0.25 mg of pramipexole and 15 were given placebo. The control group included 13 normal subjects. Nocturnal polysomnography was carried out in all subjects, and a second night was recorded after pramipexole or placebo was administered to patients with RLS. Sleep stages, CAP, and leg movement activity were scored following standard criteria., Measurements and Results: At baseline, rapid eye movement sleep latency was significantly longer in patients with RLS than in normal control subjects, and the periodic leg movement during sleep index (PLMS) was also significantly higher. On the contrary, many CAP parameters appeared to be significantly different, with a general increase in CAP rate in patients with RLS. Acute administration of pramipexole induced moderate changes in sleep architecture (increased number of stage shifts/h, sleep efficiency, and percentage of stage 2 sleep; decreased wakefulness after sleep onset; and a lower PLMS index. No effects of treatment on CAP were observed., Conclusion: Patients with RLS show significant abnormalities in sleep microstructure, represented by an excessive sleep instability/discontinuity. Acute pramipexole administration seems to exert no action on these abnormalities; the moderate effects seen on sleep architecture might be interpreted as the beneficial consequence of the removal of presleep RLS symptoms and PLMS.

Recently, the new American Academy of Sleep Medicine (AASM) rules and the old Rechtschaffen and Kales (R&K) criteria for sleep scoring have been shown to produce significantly different results in adults. The aim of this study was to describe in detail such differences in a group of normal children. Polysomnographic recordings from 45 healthy children (18 females and 27 males) aged between 3 and 16 years were scored following both systems and the results compared. Several significant differences between the two scoring systems were found: N1 (AASM) was significantly higher than S1 (R&K) while Stages N2 and R (AASM) were significantly smaller than S2 and rapid eye movement (R&K). The Kendall Tau correlation coefficient revealed a relatively low concordance between the two systems for the scoring of number of stage shifts per hour, minutes and percentage of Stage N1/S1, and of a percentage of Stage S2/N2. The significant differences between R&K and AASM scoring systems suggest taking some caution in adopting the new scoring criteria in children; these might be shown to be potentially useful if careful selection of the appropriate indicators derived from this new method is carried out, such as the percentage of N1 and the number of stage shifts, which are measures very sensitive to the occurrence of arousals in the new AASM system.

Background: Laron syndrome (LS), known as growth hormone (GH) receptor deficiency, is a rare form of inherited GH resistance. Sleep disorders were described as a common feature of adult LS patients, while no data are available in children. Bi-directional interactions between human sleep and the somatotropic system were previously described, mainly between slow wave sleep and the nocturnal GH surge., Aims: To analyze the sleep macro- and microstructure in LS and to evaluate the influence of substitutive insulin-like growth factor 1 (IGF-1) therapy on it., Methods: Two young LS females underwent polysomnography; the first study was performed during IGF-1 therapy, the second one after a 3-month wash-out period., Results: In both patients, the sleep macrostructure showed that time in bed, sleep period time, total sleep time, sleep efficiency and rapid eye movement (REM) percentage were all increased during wash-out. The sleep microstructure (cyclic alternating pattern: CAP) showed significantly higher EEG slow oscillations (A1%) in NREM sleep, both during IGF-1 therapy and wash-out., Conclusions: Sleep macrostructure in LS children is slightly affected by substitutive IGF-1 therapy. Sleep microstructure shows an increase of A1%, probably related to abnormally high hypothalamic GHRH secretion, due to GH insensitivity., (Copyright 2010 S. Karger AG, Basel.)

Objective: To analyze the functional connectivity patterns of the different EEG bands during wakefulness and sleep (different sleep stages and cyclic alternating pattern (CAP) conditions), using concepts derived from Graph Theory., Methods: We evaluated spatial patterns of EEG band synchronization between all possible pairs of electrodes (19) placed over the scalp of 10 sleeping healthy young normal subjects using two graph theoretical measures: the clustering coefficient (Cp) and the characteristic path length (Lp). The measures were obtained during wakefulness and the different sleep stages/CAP conditions from the real EEG connectivity networks and randomized control (surrogate) networks (Cp-s and Lp-s)., Results: We found values of Cp and Lp compatible with a small-world network organization in all sleep stages and for all EEG bands. All bands below 15Hz showed an increase of these features during sleep (and during CAP-A phases in particular), compared to wakefulness., Conclusions: The results of this study seem to confirm our initial hypothesis that during sleep there exists a clear trend for the functional connectivity of the EEG to move forward to an organization more similar to that of a small-world network, at least for the frequency bands lower than 15Hz., Significance: Sleep network "reconfiguration" might be one of the key mechanisms for the understanding of the "global" and "local" neural plasticity taking place during sleep.

Objective: To analyze sleep architecture and NREM sleep alterations by means of the Cyclic Alternating Pattern (CAP) in children with Down syndrome (DS) and Fragile-X syndrome (fraX), the two most common causes of inherited mental retardation, in order to find out eventual alterations of their sleep microstructure related to their mental retardation phenotypes., Methods: Fourteen patients affected by fraX (mean age 13.1 years) and 9 affected by Down syndrome (mean age 13.8 years) and 26 age-matched normal controls were included. All subjects underwent overnight polysomnography in the sleep laboratory, after one adaptation night and their sleep architecture and CAP were visually scored., Results: FraX subjects showed a reduced time in bed compared to DS subjects, whereas DS subjects showed a lower sleep efficiency, a higher percentage of wakefulness after sleep onset, and a reduced percentage of stage 2 NREM compared to the other groups. Furthermore, DS and fraX subjects, compared to normal controls, showed a higher percentage of stage 1 NREM and a lower percentage of REM sleep. FraX subjects showed the most disrupted sleep microstructure with low total CAP rate and CAP rate in S2 NREM. Both patient groups showed a lower percentage of A1 and higher percentage of A2 and A3 compared to normal controls., Conclusions: The analysis of CAP might be able to disclose new important findings in the sleep architecture of children with mental retardation and might characterize sleep microstructural patterns of the different phenotypes of intellectual disability., Significance: The NREM sleep microstructure alterations found in our subjects, associated with the reduction in REM sleep percentage, seem to be distinctive features of intellectual disability.

Sleep habits and circadian preference (morningness/eveningness, M/E) have been extensively analyzed in adolescents and young adults, while few studies were conducted on children and early adolescents. Aim of the present study was to investigate the developmental changes of circadian preference and to analyze its relationship with sleep habits, sleep problems and circadian preference in a large sample by means of a school-based survey. One thousand seventy-three participants (50.8% boys and 49.2% girls; mean age = 10.6; range = 8-14 years), recruited from four schools randomly extracted within the district of Rome, completed a modified version of School Sleep Habits Survey developed by Carskadon et al. The questionnaire included items about sleep habits during schooldays and weekends; a Sleepiness Scale; a Sleep-Wake Problems Behaviour Scale; a Morningness/Eveningness scale. The results show a consistent age-related change in sleep habits, particularly in the weekends. The difference in sleep duration between schooldays and weekends increases linearly with age. No gender difference was observed in morningness/eveningness, while a significant linear increase in evening preference was found with increasing ages. M/E total scores correlated significantly with both self-reported sleep/wake problems and daytime sleepiness indicating a higher prevalence of sleep complaints in evening-type subjects. Overall, the present results support the existence of consistent age-related changes in sleep habits and M/E dimension in the 8- to 14-year age range.

Study Objectives: To evaluate NREM sleep instability, as measured by the cyclic alternating pattern (CAP), in a cohort of children with mild sleep disordered breathing (SDB) or frank obstructive sleep apnea (OSA) and normal controls., Design: Prospective study., Settings: Sleep laboratory in academic center., Participants: Twenty-two patients (13 boys; mean age 6.5 +/- 2.4 years; 10 with mild SDB and 12 with OSA) and 15 normal children matched for age underwent overnight polysomnographic recordings in a standard laboratory setting. Sleep was visually scored for sleep macrostructure and CAP in a blinded fashion using standard criteria. Markovian analysis was also performed., Measurements and Results: Participants with OSA had reduced total CAP rates than normal controls and mild SDB patients. Children with mild SDB or OSA had a lower number of A1, lower A1 percentage, and lower A1 index than controls. Children with OSA also showed longer intervals between consecutive A phases and a decrease in entropy in the Markovian analysis., Conclusions: The lower CAP rate and its reduced entropy in children with mild SDB or OSA seem to indicate the presence of subtle sleep alterations that are not clearly identifiable with other approaches and might provide more robust correlates of neurocognitive and behavioral dysfunction in snoring children.

Objective: To analyze the functional connectivity patterns of the EEG slow-wave activity during the different sleep stages and Cyclic Alternating Pattern (CAP) conditions, using concepts derived from Graph Theory., Methods: We evaluated spatial patterns of EEG slow-wave synchronization between all possible pairs of electrodes (19) placed over the scalp of 10 sleeping healthy young normal subjects using two graph theoretical measures: the clustering coefficient (Cp) and the characteristic path length (Lp). The measures were obtained during the different sleep stages and CAP conditions from the real EEG connectivity networks and randomized control (surrogate) networks (Cp-s and Lp-s)., Results: Cp and Cp/Cp-s increased significantly from wakefulness to sleep while Lp and Lp/Lp-s did not show changes. Cp/Cp-s was higher for A1 phases, compared to B phases of CAP., Conclusions: The network organization of the EEG slow-wave synchronization during sleep shows features characteristic of small-world networks (high Cp combined with low Lp); this type of organization is slightly but significantly more evident during the CAP A1 subtypes., Significance: Our results show feasibility of using graph theoretical measures to characterize the complexity of brain networks during sleep and might indicate sleep, and the A1 phases of CAP in particular, as a period during which slow-wave synchronization shows optimal network organization for information processing.

The levels of EEG synchronization, in the 0.25-2.5 Hz band, during the A1 subtypes of the sleep "cyclic alternating pattern" (CAP) were measured in five healthy subjects by means of the synchronization likelihood (SL) algorithm. SL was measured for seven electrode pairs (F4-F3, C4-C3, P4-P3 for the analysis of interhemispheric SL and F4-C4, C4-P4, F3-C3, and C3-P3, for the analysis of intrahemispheric SL). During the A1 CAP subtypes, SL tended to be highest between pairs of electrodes situated over different hemispheres; in particular, SL obtained from F4-F3 was the highest, followed by that of P4-P3. These results indicate that the transient high level of synchronization in the slow-wave EEG range, during the sleep A1 CAP subtypes, is a phenomenon involving mostly the anterior parts of the brain and is probably based on interhemispheric interactions, possibly mediated by transcallosal connections.

Study Objectives: To analyze the intervals between A phases of the cyclic alternating pattern (CAP) and to describe their time structure. This might represent an additional aspect to be studied in sleep pathologies that are accompanied by CAP changes., Methods: Sleep stages and CAP A phases were identified in polysomnographic night recordings of normal adults and children. Intervals between consecutive CAP A phases were measured, counted, and used to draw individual normalized distribution graphs. The intervals during light sleep (stages 1 and 2) were analyzed separately from those occurring during slow-wave sleep (SWS). Subsequently, we performed a Markovian analysis of intervals, in order to describe in detail their time structure., Setting: N/A., Participants: Twenty-four adults and 28 children., Measurements and Results: In adults, a preponderance of intervals shorter than 60 seconds during SWS was found; light sleep showed a higher number of intervals longer than 60 seconds. A less clear-cut difference between stages was found in children, who showed a shift of the peak in their SWS histogram toward intervals shorter than in adults. Interval sequences were not determined by a random process in both groups. The Markovian analysis showed statistically significant lower values of entropy and higher values of time dependency, mostly in adults during SWS., Conclusions: The different CAP components of sleep occur in a non-random ordered fashion, and their time structure is characterized by first-order relationships., Significance: We postulate that CAP components are the expression of a timely ordered process that exhibits specific sleep stage-related features and undergoes age-related modifications.

Objective: To study the dynamics of spatial synchronization of the slow-wave activity recorded from different scalp electrodes during sleep in healthy normal controls., Methods: We characterized the different levels of EEG synchronization during sleep (in the 0.25-2.5 Hz band) of five healthy subjects by means of the synchronization likelihood (SL) algorithm and analyzed its long-range temporal correlations by means of the detrended fluctuation analysis (DFA)., Results: We found higher levels of interregional synchronization during 'cyclic alternating pattern' (CAP) sleep than during nonCAP with a small but significant difference between its A and B phases. SL during CAP showed fluctuations probably corresponding to the single EEG slow-wave elements. DFA showed the presence of two linear scaling regions in the double-logarithmic plot of the fluctuations of SL level as a function of time scale. This indicates the presence of a characteristic time scale in the underlying dynamics which was very stable among the different subjects (1.23-1.33 s). We also computed the DFA exponent of the two scaling regions; the first, with values approximately 1.5, corresponded to fluctuations with period 0.09-0.75 s and the second, with values approximately 1, corresponded to fluctuations with period 1.5-24.0 s. Only the first exponent showed different values during the different sleep stages., Conclusions: All these results indicate a different role for each sleep stage and CAP condition in the EEG synchronization processes of sleep which show a complex time structure correlated with its neurophysiological mechanisms., Significance: Very slow oscillations in spatial EEG synchronization might play a critical role in the long-range temporal EEG correlations during sleep which might be the chain of events responsible for the maintenance and correct complex development of sleep structure during the night.