Normative values of polysomnographic parameters in childhood and adolescence: quantitative sleep parameters

Does Sleep Help Prevent Forgetting Rewarded Memory Representations in Children and Adults?

Sleep fosters the consolidation of rewarded memory representations in adults. However, sleep and its memory-supporting functions change through healthy development, and it is unclear whether sleep benefits the consolidation of rewarded memory representations in children as it does in adults. Based on previous findings, we expected sleep to benefit the consolidation of rewarded memory representations in children more than it does in adults. For that reason, 16 children (7–11 years) and 20 adults (21–29 years) participated in this experiment. During the encoding session, participants were asked to learn the location of 18 object pairs. Thereafter, one-half of the object locations were allocated to a high-rewarded condition and the other half to a low-rewarded condition. In the sleep condition, the encoding session took place in the evening (for children 7–8 pm, for adults 8–9 pm). After a fixed retention interval of 12 h the retrieval session was conducted the next morning (for children 7–8 am, for adults 8–9 am). In the wake condition, the time schedule was the same but reversed: the encoding session started in the morning (for children 7–8 am, for adults 8–9 am), and retrieval took place in the evening (for children 7–8 pm, for adults 8–9 pm). Sleep/wake had no impact on the memory performance regarding the low-rewarded memory items. In contrast, wakefulness in comparison to sleep reduced the memory performance on high-rewarded memory items. The interaction between sleep/wake and the degree of reward on memory performance was only significant in children. These results show that 12 h of wakefulness can deteriorate the memory performance for high-rewarded representations, whereas sleep can prevent the forgetting of these rewarded representations. It is discussed whether ontogenetic changes in sleep may play a role in conserving relevant but fragile memory representation.

Sleep Instabilities Assessed by Cardiopulmonary Coupling Analysis Increase During Childhood and Adolescence

The electrocardiogram-based cardiopulmonary coupling (CPC) technique may be used to track sleep instabilities. With progressing age, maturational changes during childhood and adolescence affect sleep. The objective was to assess developmental changes in sleep instabilities in a natural setting. ECGs during nighttime sleep on regular school days were recorded from 363 subjects aged 4 to 22 years (204 females). The estimated total sleep time (ETST) decreased from 598 to 445 min during childhood and adolescence. Stable sleep linearly decreased with progressing age (high frequency coupling (HFC): 70–48% ETST). Unstable sleep [low frequency coupling (LFC): 9–19% ETST], sleep fragmentation or disordered breathing (elevated LFC: 4–12% ETST), and wake/REM states [very low frequency coupling (VLFC): 20–32% ETST] linearly increased with age. Hence, with progressing age the sleep of children and adolescents shortens, becomes more unstable and is more often affected by fragmentation or sleep disordered breathing, especially in the age group >13 years. It remains to be clarified whether some of the changes are caused by a social jetlag, i.e., the misalignment of body clock and social time especially in adolescents.

Overnight auto-adjusting continuous airway pressure + standard care compared with standard care alone in the prevention of morbidity in sickle cell disease phase II (POMS2b): study protocol for a randomised controlled trial

Background

In addition to pain, sickle cell anaemia (HbSS) complications include neurocognitive difficulties in attention and processing speed associated with low daytime and night-time oxygen saturation compounded by obstructive sleep apnoea (OSA). In the general population OSA is treated with continuous positive airways pressure (CPAP). The aim of this single-blind, randomised, controlled phase II trial is to compare auto-adjusting CPAP (APAP) with standard care to standard care alone in individuals with HbSS to determine whether the intervention improves attention and processing speed, brain structure, pain and quality of life.

Methods/Design

Eligibility criteria include: ability to provide informed consent; age > 8 years; diagnosis of HbSS; and mean overnight saturation of < 90% for < 30% of the night (i.e. not meeting current criteria for overnight oxygen therapy). Key exclusion criteria are: overnight respiratory support; respiratory or decompensated cardiac failure; chronic transfusion; or contraindications to APAP therapy or magnetic resonance imaging (MRI).

Sixty individuals with HbSS (30 children and 30 adults) will be randomised to standard care + APAP or standard care alone for six months. Minimisation factors are: age group (8–11, 12–15, 16–22 and > 23 years); silent infarction on MRI; minimum overnight oxygen saturation > 90% or < 90%; and hydroxyurea use.

For APAP individuals, the intervention is administered at home. Adherence and effectiveness are recorded using software documenting hours of use each night and overnight oximetry. Participant support in terms of appropriate facemask and facilitating adherence are provided by an unblinded sleep physiologist.

The primary outcome is change in the cancellation subtest from the Wechsler scales. Secondary outcomes include general cognitive functioning, quantitative brain MRI, blood and urine chemistry, quality of life and daily pain via a smartphone App (GoMedSolutions, Inc) and, where possible MRI heart, echocardiography, and 6-min walk. These outcomes will be assessed at baseline and after six months of treatment by assessors blind to treatment assignment.

Discussion

Altering oxygen saturation in HbSS may lead to bone marrow suppression. This risk will be reduced by monitoring full blood counts at baseline, two weeks, three months and six months, providing treatment as appropriate and reporting as safety events.

Trial registration

ISRCTN46012373. Registered on 10 July 2015.

Protocol Version: 6.0 Date: 24th December 2015

Sponsor: University Hospital Southampton. Sponsor’s protocol code: RHMCHIOT53

Sleep and Skin Temperature in Preschool Children and Their Mothers

The purpose of this study was to investigate and compare sleep and skin temperature (Tsk) of preschool children with those of their mothers. The subjects included 18 pairs of preschool children and their mothers. The actigraphic measurement of sleep, Tsk, heart rate, bedroom climate, and the microclimate temperature and humidity (bed climate) were measured. Proximal and distal Tsk, the temperature gradient of distal and proximal Tsk (DPG), and bed climate temperature were significantly lower in the children. Approximately 70% of the children slept without bed covering. Heat dissipation during sleep in preschool children may primarily rely on the proximal Tsk. The lower Tsk than adults, and behavioral thermoregulation, may be important for sleep in preschoolers.

Clinical and polysomnographic characteristics of excessive daytime sleepiness in children

PURPOSE

This study aimed to delineate the clinical and polysomnography (PSG) characteristics of sleep disorders in children with excessive daytime sleepiness (EDS).

METHODS

Between February 2002 and June 2015, 622 pediatric patients with EDS were evaluated with overnight PSG and the Multiple Sleep Latency Test at the Samsung Medical Center. The medical records; questionnaire responses about depression, sleepiness, sleep habits; and sleep study data of 133 patients without obstructive sleep apnea (OSA) were reviewed retrospectively.

RESULTS

The patients (63 girls, 70 boys) slept for an average of 7 h 30 min and 8 h 44 min on weekdays and weekends, respectively. The mean Epworth Sleepiness Scale score was 11.01 ± 4.09 and did not differ significantly among sleep disorders. Among the 102 patients who completed the depression questionnaire, 53 showed depressive feelings, which were moderate or severe in 39, with no significant differences among specific sleep disorders. Thirty-four patients exhibited normal PSG results. Seventeen of them were concluded as not having any sleep disorders, and the others as having delayed sleep phase disorder (DSPD). Narcolepsy (n = 78) was the most common disorder, followed by DSPD (n = 17) and idiopathic hypersomnia (n = 12).

CONCLUSIONS

Pediatric patients with EDS had various sleep disorders and some did not have any sleep disorder despite EDS. More than half the patients with EDS showed depressive feelings affecting their daily lives. For pediatric patients with EDS, a systematic diagnostic approach including questionnaires for sleep habits and emotion and PSG is essential for accurate diagnosis and treatment.

Sleep Architecture Linked to Airway Obstruction and Intracranial Hypertension in Children with Syndromic Craniosynostosis

BACKGROUND

Children with syndromic craniosynostosis often have obstructive sleep apnea and intracranial hypertension. The authors aimed to evaluate (1) sleep architecture, and determine whether this is influenced by the presence of obstructive sleep apnea and/or intracranial hypertension; and (2) the effect of treatment on sleep architecture.

METHODS

This study included patients with syndromic craniosynostosis treated at a national referral center, undergoing screening for obstructive sleep apnea and intracranial hypertension. Obstructive sleep apnea was identified by polysomnography, and categorized into no, mild, moderate, or severe. Intracranial hypertension was identified by the presence of papilledema on funduscopy, supplemented by optical coherence tomography and/or intracranial pressure monitoring. Regarding sleep architecture, sleep was divided into rapid eye movement or non-rapid eye movement sleep; respiratory effort-related arousals and sleep efficiency were scored.

RESULTS

The authors included 39 patients (median age, 5.9 years): 19 with neither obstructive sleep apnea nor intracranial hypertension, 11 with obstructive sleep apnea (four moderate/severe), six with intracranial hypertension, and three with obstructive sleep apnea and intracranial hypertension. Patients with syndromic craniosynostosis, independent of the presence of mild obstructive sleep apnea and/or intracranial hypertension, have normal sleep architecture compared with age-matched controls. Patients with moderate/severe obstructive sleep apnea have a higher respiratory effort-related arousal index (p < 0.01), lower sleep efficiency (p = 0.01), and less rapid eye movement sleep (p = 0.04). An improvement in sleep architecture was observed following monobloc surgery (n = 5; rapid eye movement sleep, 5.3 percent; p = 0.04).

CONCLUSIONS

Children with syndromic craniosynostosis have in principle normal sleep architecture. However, moderate/severe obstructive sleep apnea does lead to disturbed sleep architecture, which fits within a framework of a unifying theory for obstructive sleep apnea, intracranial hypertension, and sleep.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, II.

Sleep-Dependent Consolidation of Rewarded Behavior Is Diminished in Children with Attention Deficit Hyperactivity Disorder and a Comorbid Disorder of Social Behavior

Children suffering from attention-deficit hyperactivity disorder (ADHD) often also display impaired learning and memory. Previous research has documented aberrant reward processing in ADHD as well as impaired sleep-dependent consolidation of declarative memory. We investigated whether sleep also fosters the consolidation of behavior learned by probabilistic reward and whether ADHD patients with a comorbid disorder of social behavior show deficits in this memory domain, too. A group of 17 ADHD patients with comorbid disorders of social behavior aged 8–12 years and healthy controls matched for age, IQ, and handedness took part in the experiment. During the encoding task, children worked on a probabilistic learning task acquiring behavioral preferences for stimuli rewarded most often. After a 12-hr retention interval of either sleep at night or wakefulness during the day, a reversal task was presented where the contingencies were reversed. Consolidation of rewarded behavior is indicated by greater resistance to reversal learning. We found that healthy children consolidate rewarded behavior better during a night of sleep than during a day awake and that the sleep-dependent consolidation of rewarded behavior by trend correlates with non-REM sleep but not with REM sleep. In contrast, children with ADHD and comorbid disorders of social behavior do not show sleep-dependent consolidation of rewarded behavior. Moreover, their consolidation of rewarded behavior does not correlate with sleep. The results indicate that dysfunctional sleep in children suffering from ADHD and disorders of social behavior might be a crucial factor in the consolidation of behavior learned by reward.

Sleep and melatonin secretion abnormalities in children and adolescents with fetal alcohol spectrum disorders

OBJECTIVES

Caregivers describe significant sleep disturbances in the vast majority of children and adolescents, which is diagnosed as fetal alcohol spectrum disorders (FASD), but objective data on sleep disorders in this population are almost completely lacking. Animal models suggest that intrauterine alcohol exposure may disrupt sleep wake patterns, cause sleep fragmentation, and specifically affect the suprachiasmatic nucleus, thus disrupting melatonin secretion. The objective of this pioneering study was to evaluate sleep and melatonin abnormalities in children with FASD using objective, gold-standard measures.

METHODS

Children and adolescents (N = 36, 6-18 years) with FASD participated in clinical assessments by sleep specialists, overnight polysomnography (PSG), and a dim light melatonin onset (DLMO) test in a pediatric sleep laboratory. PSG was analyzed according to standardized scoring guidelines and sleep architecture was compared with normative data. DLMOs were determined and melatonin secretion curves were evaluated qualitatively to classify melatonin profiles. Sleep disorders were evaluated according to international diagnostic criteria.

RESULTS

There was a high prevalence (58%) of sleep disorders. The most common sleep problems were parasomnias (27.9%) and insomnia (16.8%). The sleep studies showed lower than normal sleep efficiency and high rates of sleep fragmentation. Most participants (79%) had an abnormal melatonin profile.

CONCLUSIONS

This study led to the recognition that both sleep and melatonin secretion abnormalities are present in children with FASD. Therefore, to be effective in managing the sleep problems in children with FASD, one needs to consider both the sleep per se and a possible malfunction of the circadian regulation.

Identifying children's nocturnal sleep using 24-h waist accelerometry

PURPOSE

The purposes of this study were 1) to add layers and features to a previously published fully automated algorithm designed to identify children's nocturnal sleep and to exclude episodes of nighttime nonwear/wakefulness and potentially misclassified daytime sleep episodes and 2) to validate this refined sleep algorithm (RSA) against sleep logs.

METHODS

Forty-five fourth-grade school children (51% female) participants were asked to log evening bedtime and morning wake time and wear an ActiGraph GT3X+ (ActiGraph LLC, Pensacola, FL) accelerometer at their waist for seven consecutive days. Accelerometers were distributed through a single school participating in the Baton Rouge, USA, site of the International Study of Childhood Obesity, Lifestyle, and the Environment. We compared log-based variables of sleep period time (SPT), bedtime, and wake time to corresponding accelerometer-determined variables of total sleep episode time, sleep onset, and sleep offset estimated with the RSA. In addition, SPT and sleep onset estimated using standard procedures combining sleep logs and accelerometry (Log + Accel) were compared to the RSA-derived values.

RESULTS

RSA total sleep episode time (540 ± 36 min) was significantly different from Log SPT (560 ± 24 min), P = 0.003, but not different from Log + Accel SPT (549 ± 24 min), P = 0.15. Significant and moderately high correlations were apparent between RSA-determined variables and those using the other methods (r = 0.61 to 0.74). There were no differences between RSA and Log + Accel estimates of sleep onset (P = 0.15) or RSA sleep offset and log wake time (P = 0.16).

CONCLUSIONS

The RSA is a refinement of our previous algorithm, allowing researchers who use a 24-h waist-worn accelerometry protocol to distinguish children's nocturnal sleep (including night time wake episodes) from daytime activities.

Effects of sleep manipulation on cognitive functioning of adolescents: A systematic review

Adolescents are considered to be at risk for deteriorated cognitive functioning due to insufficient sleep. This systematic review examined the effects of experimental sleep manipulation on adolescent cognitive functioning. Sleep manipulations consisted of total or partial sleep restriction, sleep extension, and sleep improvement. Only articles written in English, with participants' mean age between 10 and 19 y, using objective sleep measures and cognitive performance as outcomes were included. Based on these criteria 16 articles were included. The results showed that the sleep manipulations were successful. Partial sleep restriction had small or no effects on adolescent cognitive functioning. Sleep deprivation studies showed decrements in the psychomotor vigilance task as most consistent finding. Sleep extension and sleep improvement contributed to improvement of working memory. Sleep directly after learning improved memory consolidation. Due to the great diversity of tests and lack of coherent results, decisive conclusions could not be drawn about which domains in particular were influenced by sleep manipulation. Small number of participants, not accounting for the role of sleep quality, individual differences in sleep need, compensatory mechanisms in adolescent sleep and cognitive functioning, and the impurity problem of cognitive tests might explain the absence of more distinct results.

Nocturnal sleep-related variables from 24-h free-living waist-worn accelerometry: International Study of Childhood Obesity, Lifestyle and the Environment

OBJECTIVES

We describe the process of identifying and defining nocturnal sleep-related variables (for example, movement/non-movement indicators of sleep efficiency, waking episodes, midpoint and so on) using the unique 24-h waist-worn free-living accelerometer data collected in the International Study of Childhood Obesity, Lifestyle and the Environment (ISCOLE).

METHODS

Seven consecutive days of 24-h waist-worn accelerometer (GT3X+, ActiGraph LLC) data were collected from over 500 children at each site. An expert subgroup of the research team with accelerometry expertize, frontline data collectors and data managers met on several occasions to categorize and operationally define nocturnal accelerometer signal data patterns. The iterative process was informed by the raw data drawn from a sub set of the US data, and culminated in a refined and replicable delineated definition for each identified nocturnal sleep-related variable. Ultimately based on 6318 participants from all 12 ISCOLE sites with valid total sleep episode time (TSET), we report average clock times for nocturnal sleep onset, offset and midpoint in addition to sleep period time, TSET and restful sleep efficiency (among other derived variables).

RESULTS

Nocturnal sleep onset occurred at 2218 hours and nocturnal sleep offset at 0707 hours. The mean midpoint was 0243 hours. The sleep period time of 529.6 min (8.8 h) was typically accumulated in a single episode, making the average TSET very similar in duration (529.0 min). The mean restful sleep efficiency ranged from 86.8% (based on absolute non-movement of 0 counts per minute) to 96.0% (based on relative non-movement of <100 counts per minute).

CONCLUSIONS

These variables extend the potential of field-based 24-h waist-worn accelerometry to distinguish and categorize the underlying robust patterns of movement/non-movement signals conveying magnitude, duration, frequency and periodicity during the nocturnal sleep period.

Developmental changes in sleep and breathing across infancy and childhood

Sleep and breathing are physiological processes that begin in utero and undergo progressive change. While the major period of change for both sleep and breathing occurs during the months after birth, considered a period of vulnerability, more subtle changes continue to occur throughout childhood. The systems that control sleep and breathing develop separately, but sleep represents an activity state during which breathing and breathing control is significantly altered. Infants and young children may spend up to 12 hours a day sleeping; therefore, the effects of sleep on breathing are fundamental to understanding both processes in childhood. This review summarizes the current literature relevant to understanding the normal development of sleep and breathing across infancy and childhood.

Good Sleep Health in Urban Children With Asthma: A Risk and Resilience Approach

OBJECTIVES

To identify children demonstrating "good" sleep health in a sample of urban children with persistent asthma; to compare sociocontextual, asthma clinical characteristics, and sleep behaviors in children with "good" versus "poor" sleep health; and to examine protective effects of family-based health behaviors on sleep health.

METHODS

Participants were 249 Black (33%), Latino (51%) and non-Latino White (16%) children with asthma, ages 7-9 years, and their primary caregivers. 

RESULTS

32 percent of children had "good" sleep health. Well-controlled asthma and better lung function were more likely in this group. In the context of urban risks, sleep hygiene appeared to be a protective factor associated with better sleep quality. The protective effect of asthma management functioned differently by ethnic group.

CONCLUSIONS

This study identifies protective processes that may guard against urban risks to optimize sleep health in children with asthma. Intervention programs can be tailored to consider specific supports that enhance sleep health in this high-risk group.

Improving wear time compliance with a 24-hour waist-worn accelerometer protocol in the International Study of Childhood Obesity, Lifestyle and the Environment (ISCOLE)

Background

We compared 24-hour waist-worn accelerometer wear time characteristics of 9–11 year old children in the International Study of Childhood Obesity, Lifestyle and the Environment (ISCOLE) to similarly aged U.S. children providing waking-hours waist-worn accelerometer data in the 2003–2006 National Health and Nutrition Examination Survey (NHANES).

Methods

Valid cases were defined as having ≥4 days with ≥10 hours of waking wear time in a 24-hour period, including one weekend day. Previously published algorithms for extracting total sleep episode time from 24-hour accelerometer data and for identifying wear time (in both the 24-hour and waking-hours protocols) were applied. The number of valid days obtained and a ratio (percent) of valid cases to the number of participants originally wearing an accelerometer were computed for both ISCOLE and NHANES. Given the two surveys’ discrepant sampling designs, wear time (minutes/day, hours/day) from U.S. ISCOLE was compared to NHANES using a meta-analytic approach. Wear time for the 11 additional countries participating in ISCOLE were graphically compared with NHANES.

Results

491 U.S. ISCOLE children (9.92±0.03 years of age [M±SE]) and 586 NHANES children (10.43 ± 0.04 years of age) were deemed valid cases. The ratio of valid cases to the number of participants originally wearing an accelerometer was 76.7% in U.S. ISCOLE and 62.6% in NHANES. Wear time averaged 1357.0 ± 4.2 minutes per 24-hour day in ISCOLE. Waking wear time was 884.4 ± 2.2 minutes/day for U.S. ISCOLE children and 822.6 ± 4.3 minutes/day in NHANES children (difference = 61.8 minutes/day, p < 0.001). Wear time characteristics were consistently higher in all ISCOLE study sites compared to the NHANES protocol.

Conclusions

A 24-hour waist-worn accelerometry protocol implemented in U.S. children produced 22.6 out of 24 hours of possible wear time, and 61.8 more minutes/day of waking wear time than a similarly implemented and processed waking wear time waist-worn accelerometry protocol. Consistent results were obtained internationally. The 24-hour protocol may produce an important increase in wear time compliance that also provides an opportunity to study the total sleep episode time separate and distinct from physical activity and sedentary time detected during waking-hours.

Trial registration

ClinicalTrials.gov NCT01722500.

Electronic supplementary material

The online version of this article (doi:10.1186/s12966-015-0172-x) contains supplementary material, which is available to authorized users.

Generalization of word meanings during infant sleep

Sleep consolidates memory and promotes generalization in adults, but it is still unknown to what extent the rapidly growing infant memory benefits from sleep. Here we show that during sleep the infant brain reorganizes recent memories and creates semantic knowledge from individual episodic experiences. Infants aged between 9 and 16 months were given the opportunity to encode both objects as specific word meanings and categories as general word meanings. Event-related potentials indicate that, initially, infants acquire only the specific but not the general word meanings. About 1.5 h later, infants who napped during the retention period, but not infants who stayed awake, remember the specific word meanings and, moreover, successfully generalize words to novel category exemplars. Independently of age, the semantic generalization effect is correlated with sleep spindle activity during the nap, suggesting that sleep spindles are involved in infant sleep-dependent brain plasticity.

Sleep is associated with offline improvement of motor sequence skill in children

In adults, sleep is necessary for the offline improvement of certain skills, such as sequential finger tapping, but whether children show a similar effect is still debatable. Here, we tested whether sleep is associated with offline performance improvement in children. Nine- and 11-year-old children trained on an explicit sequential finger tapping task. On the night following training, their parents observed and recorded the duration of each child’s sleep. The following day, all children performed a surprise retest session on the previously trained sequence. In both 9- and 11-year-old children, skill performance was significantly improved during the first retest session relative to the end of training on the previous day, confirming the offline improvement in performance. There was a significant correlation between the degree of improvement and sleep duration the night after training, suggesting that in children, as in adults, sleep is associated with offline skill enhancement.

Follow-up of obstructive sleep apnea in children

INTRODUCTION

the evolution of snoring and OSAS in children is not well established since few studies of patients without surgical treatment have been published.

OBJECTIVE

to evaluate the evolution of sleep disordered breathing in children who had not been submitted to upper airway surgery.

METHOD

twenty-six children with snoring who had not undergone upper airway surgery were evaluated prospectively. Patients were evaluated by full physical examination and nocturnal polysomnography, after which they were divided into 2 groups: apnea (16 children) and snoring (10 children). After 6 months following the initial evaluation, patients were submitted to a new nocturnal polysomnography, and all data were compared to those of the first examination.

RESULTS

the groups did not show any differences regarding age, weight, height and airway physical examination. After 6 months of follow-up, the apnea index did not change, but the respiratory disturbance index increased in the snoring group and the number of hypopneas decreased in the group apnea.

CONCLUSION

there was an increase in the percentage of N1 sleep stage and the respiratory disturbance index in the patients with primary snore. The AHI did not show significant alteration in both groups, but the number of hypopneas decreased in patients with SAOS.

Efficacy of internet and group-administered cognitive behavioral therapy for insomnia in adolescents: a pilot study

Research indicates that adolescents are at risk for insomnia, but are reluctant to seek help. Treatment of insomnia has been extensively examined in adults, but studies with adolescents are sparse. The purpose of this pilot study was to assess feasibility and efficacy of cognitive behavioral therapy for insomnia (CBT-i) for adolescents in both group and Internet settings. Twenty-six adolescents received 6 weekly sessions of CBT-i in a group (N = 13) or individual Internet setting (N = 13). Their sleep was measured with actigraphy, sleep logs, and questionnaires at baseline, posttreatment, and a 2-month follow up. For both treatments, results show a significant improvement, with medium to large effect sizes (ESs) of sleep onset latency, wake after sleep onset, and sleep efficiency. There was also a small ES increase of total sleep time in sleep log measures, but not in actigraphy measures. On questionnaires measuring symptoms of insomnia and chronic sleep reduction, significant improvements occurred either at posttreatment or at follow up. No differences were found between the groups. This study indicates CBT-i, either in group or in Internet formats, is an effective treatment for insomnia in adolescents. Further studies in a randomized controlled design are warranted.

Sleep duration predicts cardiometabolic risk in obese adolescents

OBJECTIVE

To examine the independent contributions of objectively measured sleep duration and fragmentation on cardiometabolic risk accumulation in free-living obese adolescents.

STUDY DESIGN

Characteristics of metabolic syndrome (waist circumference, mean arterial pressure, fasting high-density lipoprotein cholesterol, triglycerides, glucose) were measured in obese adolescents and standardized residuals (z-scores) were summed (inverse high-density lipoprotein cholesterol) to create a continuous cardiometabolic risk score (cMetScore), adjusted for age, sex, and race. Sleep and physical activity were objectively measured in habitual, free-living conditions for 7 days (SenseWear Pro3, BodyMedia, Pittsburgh, Pennsylvania; n = 37; 54% female, ages 11-17 years). Associations between sleep duration and cMetScore were assessed via multiple linear regression.

RESULTS

Body mass index, total sleep time, and sleep session length were each correlated with cMetScore (P < .05 all). Total sleep time was inversely and independently associated with cMetScore (r = -0.535, P = .001) and was the best independent predictor of metabolic risk.

CONCLUSIONS

Sleep duration inversely predicts cardiometabolic risk in obese adolescents, even when we controlled for various measures of physical activity, anthropometry, and adiposity. Further research should investigate the biological mechanism of this relationship and the potential treatment effect of sleep intervention in decreasing cardiometabolic risk in this population.

Assessment of sleep in children with mucopolysaccharidosis type III

Sleep disturbances are prevalent in mucopolysaccharidosis Type III (MPS III), yet there is a lack of objective, ecologically valid evidence detailing sleep quantity, quality or circadian system. Eight children with MPS III and eight age-matched typically developing children wore an actigraph for 7–10 days/nights. Saliva samples were collected at three time-points on two separate days, to permit analysis of endogenous melatonin levels. Parents completed a sleep questionnaire and a daily sleep diary. Actigraphic data revealed that children with MPS III had significantly longer sleep onset latencies and greater daytime sleep compared to controls, but night-time sleep duration did not differ between groups. In the MPS III group, sleep efficiency declined, and sleep onset latency increased, with age. Questionnaire responses showed that MPS III patients had significantly more sleep difficulties in all domains compared to controls. Melatonin concentrations showed an alteration in the circadian system in MPS III, which suggests that treatment for sleep problems should attempt to synchronise the sleep-wake cycle to a more regular pattern. Actigraphy was tolerated by children and this monitoring device can be recommended as a measure of treatment success in research and clinical practice.

Guidelines for the recording and evaluation of pharmaco-sleep studies in man: the International Pharmaco-EEG Society (IPEG)

The International Pharmaco-EEG Society (IPEG) presents guidelines summarising the requirements for the recording and computerised evaluation of pharmaco-sleep data in man. Over the past years, technical and data-processing methods have advanced steadily, thus enhancing data quality and expanding the palette of sleep assessment tools that can be used to investigate the activity of drugs on the central nervous system (CNS), determine the time course of effects and pharmacodynamic properties of novel therapeutics, hence enabling the study of the pharmacokinetic/pharmacodynamic relationship, and evaluate the CNS penetration or toxicity of compounds. However, despite the presence of robust guidelines on the scoring of polysomnography -recordings, a review of the literature reveals inconsistent -aspects in the operating procedures from one study to another. While this fact does not invalidate results, the lack of standardisation constitutes a regrettable shortcoming, especially in the context of drug development programmes. The present guidelines are intended to assist investigators, who are using pharmaco-sleep measures in clinical research, in an effort to provide clear and concise recommendations and thereby to standardise methodology and facilitate comparability of data across laboratories.

Validating the Children's Sleep Habits Questionnaire Against Polysomnography and Actigraphy in School-Aged Children

Sleep is a vital physiological behavior in children's development, and as such it is important to be able to efficiently and accurately assess whether children display difficulties with sleep quality and quantity. The Children's Sleep Habits Questionnaire [CSHQ; (1)] is one of the most commonly used assessment tools for pediatric sleep. However, this instrument has never been validated against the gold standard of sleep measurement [i.e., polysomnography (PSG)], and studies comparing it to actigraphy are limited. Therefore, the current study assessed the validity of four subscales of the CSHQ via direct comparison with PSG and actigraphy for 30 typically developing school-aged children (ages 6-12). No significant correlations between relevant CSHQ subscales and PSG variables were found. In terms of the actigraphy variables, only the CSHQ Night Wakings subscale achieved significance. In addition, sensitivity and specificity analyses revealed consistently low sensitivity and high specificity. Overall, the CSHQ Sleep Onset Delay, Sleep Duration, Night Wakings, and Sleep Disordered Breathing subscales showed low construct validity and diagnostic validity. These results underscore that caution should be taken when using the CSHQ as the sole screening tool for sleep problems in children.

Physical activity (PA) and sleep among children and adolescents with cancer

BACKGROUND

Although sleep and physical activity often are impaired among adult cancer patients, there is limited data among pediatric oncology populations. We conducted a prospective study to investigate the relationship between physical activity (PA) and sleep among children with cancer.

PROCEDURE

Between 11/12/09 and 02/06/12, PA while awake and sleep variables were assessed by actigraphy collected over 7 days in 36 children (age range 8-18 years) with cancer (23 leukemia/lymphoma, 5 brain tumor, 8 solid tumor). Sleep diaries were used to determine sleep time, sleep quality, and morning mood. Fatigue was assessed at study initiation using fatigue instruments.

RESULTS

Participants had impaired sleep based upon normative data compiled from multiple studies of more than 1,700 healthy children from 1 to 18 years of age [1], including decreased total sleep time (mean 6.6 hours, standard deviation (SD) 1.3 hours), increased wake after sleep onset (WASO; mean 2 hours, SD 1.4 hours), increased awakenings during sleep (mean 28.3 wake bouts, SD 7.8 bouts), and decreased sleep efficiency (mean 74.2%, SD 13.3%). Fatigue correlated with self-reported sleep quality but not with disturbances in sleep as measured by actigraphy. In longitudinal models that controlled for age, diagnosis group, gender, race, and steroid use, higher average activity, as measured by actigraphy, was associated with improved sleep quantity (P = 0.005) and efficiency (P = 0.001).

CONCLUSION

Pediatric oncology patients demonstrate impaired sleep. Greater PA was significantly associated with improved sleep quantity and efficiency in pediatric oncology participants. As a potentially modifiable factor, PA may offer a mechanism to improve sleep in pediatric oncology patients.

Respiratory and polysomnographic values in 3- to 5-year-old normal children at higher altitude

STUDY OBJECTIVES

To determine polysomnographic parameter differences in children living at higher altitude to children living near sea level.

DESIGN AND SETTING

Prospective study of non-snoring, normal children recruited from various communities around Denver, CO. In-lab, overnight polysomnograms were performed at a tertiary care children's hospital. All children required residence for greater than one year at an elevation around 1,600 meters.

PARTICIPANTS

45 children (62% female), aged 3-5 years, 88.9% non-Hispanic white with average BMI percentile for age of 47.8% ± 30.7%.

MEASUREMENTS AND RESULTS

Standard sleep indices were obtained and compared to previously published normative values in a similar population living near sea level (SLG). In the altitude group (AG), the apnea-hypopnea index was 1.8 ± 1.2 and the central apnea-hypopnea index was 1.7 ± 1.1, as compared to 0.9 ± 0.8 and 0.8 ± 0.7, respectively, (P ≤ 0.005) in SLG. Mean end-tidal CO2 level in AG was 42.3 ± 3.0 mm Hg and 40.6 ± 4.6 mm Hg in SLG (P = 0.049). The ≥ 4% desaturation index was 3.9 ± 2.0 in AG compared to 0.3 ± 0.4 in SLG (P < 0.001). Mean periodic limb movement in series index was 10.1 ± 12.3 in AG and 3.6 ± 5.4 in SLG (P = 0.001).

CONCLUSION

Comparison of altitude and sea level sleep studies in healthy children reveals significant differences in central apnea, apneahypopnea, desaturation, and periodic limb movement in series indices. Clinical providers should be aware of these differences when interpreting sleep studies and incorporate altitude-adjusted normative values in therapeutic-decision making algorithms.

Identifying adolescent sleep problems

OBJECTIVES

To examine the efficacy of self-report and parental report of adolescent sleep problems and compare these findings to the incidence of adolescents who fulfill clinical criteria for a sleep problem. Sleep and daytime functioning factors that predict adolescents' self-identification of a sleep problem will also be examined.

METHOD

308 adolescents (aged 13-17 years) from eight socioeconomically diverse South Australian high schools participated in this study. Participants completed a survey battery during class time, followed by a 7-day Sleep Diary and the Flinders Fatigue Scale completed on the final day of the study. Parents completed a Sleep, Medical, Education and Family History Survey.

RESULTS

The percentage of adolescents fulfilling one or more of the criteria for a sleep problem was inordinately high at 66%. Adolescent self-reporting a sleep problem was significantly lower than the adolescents who had one or more of the clinical criteria for a sleep problem (23.1% vs. 66.6%; χ(2) = 17.46, p<.001). Parental report of their adolescent having a sleep problem was significantly lower than adolescent self-report (14.3% vs. 21.1%, p<.001). Adolescents who reported unrefreshing sleep were 4.81 times more likely to report a sleep problem. For every hour that bedtime was delayed, the odds of self-reporting a sleep problem increased by 1.91 times, while each additional 10 minutes taken to fall asleep increased the odds 1.40 times.

CONCLUSION

While many adolescents were found to have sleep patterns indicative of a sleep problem, only a third of this number self-identify having a sleep problem, while only a sixth of this number are indicated by parental report. This study highlights important features to target in future sleep education and intervention strategies for both adolescents and parents.

Characterization of the acute pulse transit time response to obstructive apneas and hypopneas in preschool children with sleep-disordered breathing

BACKGROUND

Surges in heart rate (HR) and blood pressure (BP) at apnea termination contribute to the hypertension seen in obstructive sleep apnea (OSA). Because childhood OSA prevalence peaks in the preschool years, we aimed to characterize the cardiovascular response to obstructive events in preschool-aged children.

METHODS

Clinically referred children aged 3-5 years were grouped by obstructive apnea-hypopnea index (OAHI) into the following: primary snoring (PS) (OAHI≤1 event/h [n=21]), mild OSA (OAHI>1-≤5 [n=32]), and moderate to severe (MS) OSA (OAHI>5 [n=28]). Beat-to-beat pulse transit time (PTT), an inverse continuous indicator of BP changes, and HR were averaged during the two halves (early and late) and during the peak after (post) each obstructive event and were expressed as percentage change from late- to post-event.

RESULTS

We analyzed 422 events consisting of 55 apneas and 367 hypopneas. A significant post-event increase in HR and fall in PTT occurred in all severity groups (P<.05 for all). A greater response was associated with OSA, nonrapid eye movement sleep (NREM), cortical arousal, hypopneas, and oxygen desaturation (P<.05 for all).

CONCLUSIONS

Obstructive events elicit acute cardiovascular changes in preschool children. Such circulatory perturbations have been implicated in the development of hypertension, and our findings complement previous studies to suggest a cumulative impact of snoring on the cardiovascular system from childhood into adulthood.

Behavioral Sleep Problems and their Potential Impact on Developing Executive Function in Children

Bedtime resistance and night waking are common sleep problems throughout childhood, especially in the early years. These sleep problems may lead to difficulties in neurobehavioral functioning, but most research into childhood sleep problems has not emphasized the importance of the developmental context in which disruptions in neurobehavioral and daytime functioning occur. We review the development of sleep as well as executive functioning (EF) in childhood and suggest that EF may be particularly vulnerable to the effects of these common childhood sleep problems because of its prolonged course of maturation. Behavioral problems associated with common sleep problems suggest poor self-regulation in the context of sleep loss, and developing EF skills play important roles in self-regulation. A research agenda that considers a developmental approach to sleep and sleep problems in the context of childhood EF performance is outlined to promote future research in this area.

CITATION

Turnbull K; Reid GJ; Morton JB. Behavioral sleep problems and their potential impact on developing executive function in children. SLEEP 2013;36(7):1077-1084.

Fully automated waist-worn accelerometer algorithm for detecting children's sleep-period time separate from 24-h physical activity or sedentary behaviors

Analysis of 24-h waist-worn accelerometer data for physical activity and sedentary behavior requires that sleep-period time (from sleep onset to the end of sleep, including all sleep epochs and wakefulness after onset) is first identified. To identify sleep-period time in children in this study, we evaluated the validity of a published automated algorithm that requires nonaccelerometer bed- and wake-time inputs, relative to a criterion expert visual analysis of minute-by-minute waist-worn accelerometer data, and validated a refined fully automated algorithm. Thirty grade 4 schoolchildren (50% girls) provided 24-h waist-worn accelerometry data. Expert visual inspection (criterion), a published algorithm (Algorithm 1), and 2 additional automated refinements (Algorithm 2, which draws on the instrument's inclinometer function, and Algorithm 3, which focuses on bedtime and wake time points) were applied to a standardized 24-h time block. Paired t tests were used to evaluate differences in mean sleep time (expert criterion minus algorithm estimate). Compared with the criterion, Algorithm 1 and Algorithm 2 significantly overestimated sleep time by 43 min and 90 min, respectively. Algorithm 3 produced the smallest mean difference (2 min), and was not significantly different from the criterion. Relative to expert visual inspection, our automated Algorithm 3 produced an estimate that was precise and within expected values for similarly aged children. This fully automated algorithm for 24-h waist-worn accelerometer data will facilitate the separation of sleep time from sedentary behavior and physical activity of all intensities during the remainder of the day.

The AASM Scoring Manual four years later

PURPOSE OF REVIEW

Review published studies and critiques which evaluate the impact and effects of the American Academy of Sleep Medicine (AASM) Sleep Scoring Manual in the four years since its publication.

FINDINGS

USING THE AASM MANUAL RULES TO SCORE SLEEP AND EVENTS IN A POLYSOMNOGRAM (PSG) RESULTS IN: (1) very large differences in apnea-hypopnea indexes (AHI) when using the recommended and alternative rule for scoring hypopneas in adults; (2) increases in NREM 1 and sleep stage shifts with compensatory decreases in NREM 2 in children and adults when following rule 5.C.b. for ending NREM 2 sleep; (3) increases in NREM 3 in adults scoring slow wave activity in the frontal EEG derivations; (4) improved interscorer reliability; and (5) successfully identified fragmented sleep in children with obstructive sleep apnea (OSA) from primary snorers or normal controls because they had more NREM 1 and stage shifts using rule 5.C.b. Criticism of the Manual most often cited: (1) two rules for scoring hypopneas; (2) alternative EEG montage cancellation effects; (3) scoring stages 3 and 4 as NREM 3; and (4) too few rules for scoring arousals and REM sleep without atonia.

SUMMARY

Four years have passed since the AASM Scoring Manual was published with far less criticism than those who developed it feared. The AASM Manual provides a foundation upon which we all can build rules and methods which identify the complexity of sleep and its disorders.

Pediatric periodic limb movement disorder: sleep symptom and polysomnographic correlates compared to obstructive sleep apnea

STUDY OBJECTIVES

Although periodic limb movements in sleep (PLMS) have been described in multiple pediatric publications, periodic limb movement disorder (PLMD) has not. The aims of this study were to describe the prevalence, sleep-related correlates, and polysomnographic correlates of PLMD in a large pediatric case series, and compare these to pediatric obstructive sleep apnea (OSA).

METHODS

All PLMD cases (defined by International Classification of Sleep Disorders, 2nd edition criteria + respiratory disturbance index [RDI] < 3) and OSA cases (defined by RDI ≥ 3 + PLMS < 5), from a single pediatric sleep practice, over a 2-year time span, were included. Chart, questionnaire, and polysomnographic data were compiled. Of 468 referred children, 66 PLMD cases were identified (14%).

RESULTS

The PLMD cases, mean age 8.1 years (range 1-17), were clinically characterized by frequent sleep onset and maintenance problems, difficulty awakening, restless sleep, leg pain/discomfort at night, and parasomnias. Compared to 90 OSA children, those with PLMD had a history of significantly more sleep onset and maintenance problems, leg pain/discomfort at night, parasomnias, getting out of bed at night, and family history of restless legs syndrome. Polysomnographically, PLMD cases had more awakenings, stage 1 sleep, stage shifts, and spontaneous arousals.

CONCLUSIONS

These data indicate that pediatric PLMD has important clinical and polysomnographic correlates. In addition, PLMD has many characteristics that are different from pediatric OSA, suggesting that PLMD is a distinct pediatric sleep disorder, of which clinicians should be aware.

Normative values of polysomnographic parameters in childhood and adolescence: arousal events

OBJECTIVE

This study focused on differences in arousals during sleep, using the arousal rules of the American Academy of Sleep Medicine, by gender, age, and maturity in healthy children.

METHODS

One-night polysomnography was performed on 209 healthy German children (age 1-18 years) at their habitual bedtimes in 16 laboratories. Subjects were grouped by gender (112 females, 97 males), age, and Tanner stage.

RESULTS

Normative values of arousal events in sleep are presented, including indexes of spontaneous and respiratory arousals, total electroencephalogram (EEG) arousals, phasic increase in submental electromyogram (EMG) in stage R, and leg movements. With increasing age, a decrease was seen in: EEG arousal index ≥1-2.9 s, EEG arousal index ≥3 s, index of total EEG arousals, index of respiratory arousals, chin EMG enhancement in stage R ≥1-2.9 and ≥3 s, index of total leg movements, and leg movements with EEG arousals (p<0.05). Only spontaneous arousals showed no association with age. There was a significant negative correlation between Tanner stage and arousals ≥1-2.9 s, respiratory arousals, leg movements, and leg movements with arousals (p<0.05). Only arousals ≥3 s and total leg movements showed gender differences (p<0.05).

CONCLUSIONS

For the diagnosis of pediatric sleep disturbances, the given arousal data enable estimation of the degree of deviation from normal findings for age and maturity. There is need for further research on, and further discussion of, the arousal rules of the American Academy of Sleep Medicine.

Temporal associations between daytime physical activity and sleep in children

OBJECTIVES

We examined temporal associations between objectively-measured physical activity (PA) during the day and in the evening, and sleep quantity and quality.

STUDY DESIGN

PA and sleep were measured by actigraphs for an average of one week in an epidemiological cohort study of 275 eight-year-old children.

RESULTS

For each one standard deviation (SD) unit of increased PA during the day, sleep duration was decreased by 0.30, sleep efficiency by 0.16, and sleep fragmentation increased by 0.08 SD units that night. For each one SD unit increase in sleep duration and efficiency the preceding night, PA the following day decreased by 0.09 and 0.16 SD units, respectively. When we contrasted days with a high amount of moderate to vigorous activity during the day or in the evening to days with a more sedentary profile, the results were essentially similar. However, moderate to vigorous PA in the evening shortened sleep latency.

CONCLUSIONS

The relationship between a higher level of PA and poorer sleep is bidirectional. These within-person findings challenge epidemiological findings showing that more active people report better sleep. Since only a few studies using objective measurements of both PA and sleep have been conducted in children, further studies are needed to confirm/refute these results.