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Introduction: Social media interactions via email and instant messaging (E/IM) are common in children and adolescents and may lead to insufficient sleep. This study investigated associations between high-frequency E/IM use to interact with peers, perceived insufficient sleep, and reduced time in bed (TIB) in female children and adolescents. Methods: The Children's Report of Sleep Patterns was completed by 189 female primary and secondary school students (8-16 years old). Responses were categorized as binary variables (high-frequency use vs not high-frequency use; right amount of sleep vs too little sleep), and TIB was calculated from bed and wake times for the previous 24 hours. Results: High-frequency social media interactions using E/IMduring the hour before bed were significantly associated with perceived insufficient sleep (odds ratio [confidence interval]: 2.68 [1.39-5.17]) but not with reduced TIB (−19.07 [−40.02 to 1.89]). Conclusions: High-frequency social media interactions using E/IM in the hour before bed are a potentially modifiable risk factor for insufficient sleep in female students. Strategies to reduce nighttime usage may improve sleep in children and adolescents. Refereed/Peer-reviewed

Study objective Parents tend to under-report symptoms suggestive of sleep disordered breathing (SDB) at medical consultation. It is thought that a contributing factor may be whether parents view SDB symptoms as a problem. The aim of the study was to examine to what extent parents view SDB symptoms as a problem in children recruited from the general community and especially in children who currently have symptoms suggestive of SDB. Methods Parents of 1639 children aged 5–10 y attending middle school in South Australia completed a questionnaire which included demographics and assessed the frequency over the previous school week of 32 sleep habits including six SDB sleep habit items. The sample was restricted to typically developing children and excluded children with medical problems likely to impact SDB. The final sample included 1610 children without a prior diagnosis of SDB and 29 with a prior diagnosis and/or treatment of SDB. Parents were asked to rate children's sleep habits using a 4-pt scale (never, rarely, sometimes and usually) and if the sleep habit was perceived to be a problem (yes/no). Children who sometimes or usually reported a sleep habit item were labelled as symptomatic. Results Parents of children with, compared to those without, a prior diagnosis of SDB, were more likely to report the presence of SDB symptoms which were more frequently viewed as a problem. In children without a prior diagnosis of SDB, parents of symptomatic children viewed most SDB symptoms as a problem ranging from 91% for apnoea, 63% snorted/gasped, 63% watched child breathing at night, 58% snored loudly, 49% snored to 32% breathing heavily at night. Additional analyses in the combined sample revealed that a prior diagnosis of SDB, gender, socioeconomic status and ethnicity were weak predictors of whether parents viewed SDB sleep symptoms as a problem. Conclusion In children with symptoms suggestive of SDB, most parents viewed most SDB symptoms as a problem especially apnoea. The high frequency is contrary to that expected given the under-reporting of SDB symptoms at medical consultation. This suggests that additional factors other than whether parents consider SDB symptoms as a problem might better explain the under-reporting of SDB symptoms at medical consultation. Given the important impact on child health and medical service provision, future studies examining the factors that prompt parents to discuss SDB symptoms at medical consultation are warranted.

Childhood sleep-disordered breathing ranges in severity from primary snoring to obstructive sleep apnea and is associated with behavioral and neurocognitive deficits. It remains unknown why children with primary snoring, who do not experience peripheral oxygen desaturation or sleep fragmentation, experience similar daytime deficits as those with obstructive sleep apnea or why effects are age-dependent.To examine cerebral tissue oxygenation and oxygen extraction as an explanation for daytime deficits in children with primary snoring.Children referred for suspected sleep-disordered breathing and nonsnoring control subjects underwent overnight polysomnography with near-infrared spectroscopy. Children were categorized into 3- to 6-year (n = 87) and 7- to 12-year (n = 72) old groups, and according to the obstructive apnea-hypopnea index into primary snoring (≤1 event/h), mild (1-5 events/h), and moderate/severe obstructive sleep apnea (5 events/h). Cognitive and behavioral performance were assessed.In the 3- to 6-year group, there were no differences in cerebral oxygenation or oxygen extraction between severity groups. In the 7- to 12-year group, cerebral oxygenation was significantly lower, although these differences were small, in control subjects versus primary snoring during quiet wakefulness before sleep onset, N1, and REM. Oxygen extraction was significantly higher in control subjects versus primary snoring during N1 sleep, with no differences between primary snoring and obstructive sleep apnea groups. Cerebral oxygenation was not associated with cognitive performance in either age group or behavior in the 3- to 6-year group; however, it was associated with behavior in the school-aged children.Children with sleep-disordered breathing are able to maintain cerebral oxygenation, and the small changes observed are not related to cognitive deficits. However, in older children these differences were related to behavioral measures.

Study ObjectivesSleep disordered breathing (SDB) in children has significant effects on daytime functioning and cardiovascular control; attributed to sleep fragmentation and repetitive hypoxia. Associations between electroencephalograph (EEG) spectral power, autonomic cardiovascular control and cerebral oxygenation have been identified in adults with SDB. To date, there have been no studies in children. We aimed to assess associations between EEG spectral power and heart rate variability as a measure of autonomic control, with cerebral oxygenation in children with SDB.MethodsOne hundred sixteen children (3–12 years) with SDB and 42 controls underwent overnight polysomnography including measurement of cerebral oxygenation. Power spectral analysis of the EEG derived from C4-M1 and F4-M1, quantified delta, theta, alpha, and beta waveforms during sleep. Multiple regression tested whether age, SDB severity, heart rate (HR), HR variability (HRV), and cerebral oxygenation were determinants of EEG spectral power.ResultsThere were no differences in EEG spectral power derived from either central or frontal regions for any frequency between children with different severities of SDB so these were combined. Age, HR, and HRV low frequency power were significant determinants of EEG spectral power depending on brain region and sleep stage.ConclusionThe significant findings of this study were that age and autonomic control, rather than cerebral oxygenation and SDB severity, were predictive of EEG spectral power in children. Further research is needed to elucidate how the physiology that underlies the relationship between autonomic control and EEG impacts on the cardiovascular sequelae in children with SDB.

Study objectives Both central and obstructive respiratory events are features of sleep disordered breathing. The repetitive hypoxia associated with obstructive events is believed to underpin the adverse neurocognitive and cardiovascular sequelae of this disorder, however whether central events contribute to this has not been investigated. To compare changes in cerebral and peripheral oxygenation, blood pressure and heart rate, associated with central and obstructive events in children aged 3-6 and 7-12 years. Methods Sixty children referred for suspected sleep disordered breathing underwent overnight polysomnography. Beat-by-beat analysis determined changes from baseline in cerebral oxygenation, peripheral oxygen saturation, fractional tissue oxygen extraction, pulse transit time (a surrogate measure of blood pressure change), and heart rate, associated with central and obstructive respiratory events, during NREM and REM sleep. Results Eight hundred ninty-two events were analyzed: 493 central and 399 obstructive. Central events had a greater % change from baseline in cerebral oxygenation and heart rate nadir compared with obstructive events and these were greater in NREM compared with REM sleep. The 3- to 6-year-old children experienced a greater % change in TOI compared with the 7-12 year olds, while % change in heart rate was greater in 7-12 year olds. Conclusion Central respiratory events had similar falls in cerebral oxygenation and heart rate to obstructive events and should be considered when examining the sequelae of sleep disordered breathing, particularly as central events are common in children with sleep disordered breathing.

Aim This study aims to determine whether demographic or clinical factors predict obstructive sleep apnoea (OSA) severity in Australian children. Methods Demographic details and medical histories of 301 Australian children (3–17 years old) referred for assessment of OSA were examined retrospectively. Children underwent overnight polysomnography and were classified as having primary snoring (PS) (obstructive apnoea hypopnoea index (OAHI) ≤ 1 event per hour; n = 150), mild OSA (>1 OAHI ≤ 5 events per hour; n = 76) or moderate/severe (MS) OSA (OAHI > 5 events per hour; n = 75). Information obtained from parent-report questionnaire determined the predictive value of the following factors for determining OSA severity: gender, ethnicity, body mass index, asthma and/or allergic rhinitis, socio-economic status and parental smoking status (mother/father/both). Chi-squared analyses were used to compare the distribution of the demographic and clinical factors across the three groups. Statistically significant risk factors were subsequently entered into logistic regression analysis. Results Ethnicity and parental smoking were significant risk factors for MS OSA. Children with non-Caucasian ethnicity were 36% more likely than Caucasian children to be diagnosed with MS OSA than PS (P = 0.002). Children with fathers who smoked were 53% more likely to have MS OSA than PS compared with those with fathers who did not smoke (P = 0.008). Obesity was associated with OSA severity in primary school-aged children only. Gender, socio-economic status and history of asthma and/or allergic rhinitis were not risk factors. Conclusions Non-Caucasian ethnicity, paternal smoking and obesity in older children were associated with an increased risk of polysomnography-confirmed MS OSA in Australian children.

Background: Despite the widespread use of actigraphy in pediatric sleep studies, there are currently no age-related normative data.Objectives: To systematically review the literature, calculate pooled mean estimates of actigraphy-derived pediatric nighttime sleep variables and to examine the magnitude of change with age.Methods: A systematic search was performed across eight databases of studies that included at least one actigraphy sleep variable from healthy children aged 0-18 years. Data suitable for meta-analysis were confined to ages 3-18 years with seven actigraphy variables analyzed using random effects meta-analysis and meta-regression performed using age as a covariate.Results: In total, 1334 articles did not meet inclusion criteria; 87 had data suitable for review and 79 were suitable for meta-analysis. Pooled mean estimates for overnight sleep duration declined from 9.68 hours (3-5 years age band) to 8.98, 8.85, 8.05, and 7.4 for age bands 6-8, 9-11, 12-14, and 15-18 years, respectively. For continuous data, the best-fit (R-2 = 0.74) equation for hours over the 0-18 years age range was 9.02 - 1.04 x [(age/10)(boolean AND)2 - 0.83]. There was a significant curvilinear association between both sleep onset and offset with age (p < .001). Sleep latency was stable at 19.4 min per night. There were significant differences among the older age groups between weekday and weekend/nonschool days (18 studies). Total sleep time in 15-18 years old was 56 min longer, and sleep onset and offset almost 1 and 2 hours later, respectively, on weekend or nonschool days.Conclusion: These normative values have potential application to assist the interpretation of actigraphy measures from nighttime recordings across the pediatric age range, and aid future research. Refereed/Peer-reviewed

Study question Does melatonin result in a dose-response effect on sleep quality and daytime sleepiness in women undergoing IVF? Summary answer Melatonin, even when given at high doses twice per day, does not cause significant daytime sleepiness or change night time sleep quantity or quality. What is known already Melatonin is being increasingly used as an adjuvant therapy for women undergoing IVF owing to its antioxidative effects. It is widely considered to be sedative but there are scant objective data on the effects of melatonin on sleep in the setting of IVF. Study design size duration The study was a double-blind placebo-controlled randomized trial of 116 women recruited between September 2014 and September 2016. Participants/materials setting method Women who were undergoing their first cycle of IVF at private IVF centers were recruited into the RCT and randomized to receive either placebo, 2 mg, 4 mg or 8 mg of melatonin, twice per day (BD) from Day 2 of their cycle until the day before oocyte retrieval. Each participant wore an accelerometer that provides an estimate of sleep and wake activity for up to 1 week of baseline and throughout treatment (up to 2 weeks). They also kept sleep diaries and completed a Karolinska sleepiness score detailing their night time sleep activity and daytime sleepiness, respectively. Main results and the role of chance In total, 116 women were included in the intention-to-treat analysis (placebo BD (n = 32), melatonin 2 mg BD (n = 29), melatonin 4 mg BD (n = 26), melatonin 8 mg BD (n = 29)). There were no significant differences in daytime Karolinska sleepiness score between groups (P = 0.4), nor was there a significant dose-response trend (β=0.05, 95% CI -0.22-0.31, P = 0.7). There were no differences in objective measures of sleep quantity or quality, including wake after sleep onset time, sleep onset latency, and sleep efficiency before and after treatment or between groups. There was an improvement in subjective sleep quality scores from baseline to during treatment in all groups, except 8 mg BD melatonin: placebo (percentage change -13.3%, P = 0.01), 2 mg (-14.1%, P = 0.03), 4 mg (-8.6%, P = 0.01) and 8 mg (-7.8%, P = 0.07). Limitations reasons for caution As this was a subset of a larger trial, the melatonin in ART (MIART) trial, it is possible that the sample size was too small to detect statistically significant differences between the groups. Wider implications of the findings While this study suggests that melatonin can be used twice per day at high doses to achieve sustained antioxidation effects, with the reassurance that this will not negatively impact daytime sleepiness or night time sleep habits, the sample size is small and may have missed a clinically significant difference. Nevertheless, our findings may have implications not only for future studies of fertility treatments (including meta-analyses), but also in other medical fields where sustained antioxidation is desired. Study funding/competing interests This study was funded by the Monash IVF Research and Education Foundation (PY12_15). S.F. is supported by the National Health and Medical Research Council (Postgraduate Scholarship APP1074342) and the Royal Australian and New Zealand College of Obstetricians and Gynaecologists Ella Macknight Memorial Scholarship. E.W. is supported by an National Health and Medical Research Council Program Grant (APP1113902). S.F., E.W., R.H., B.V., N.L., N.H., M.W., M.L., A.L., P.T., K.L. have nothing to declare. L.R. is a Minority shareholder in Monash IVF Group, has unrestricted grants from MSD®, Merck-Serono® and Ferring® and receives consulting fees from Ferring®. S.N.B. reports consulting fees from Johnson & Johnson Consumer Inc®, outside the submitted work. Trial registration number This trial was prospectively registered with the Australian New Zealand Clinical Trials Registry (Project ID: ACTRN12613001317785). Trial registration date 27/11/2013. Date of first patient’s enrolment 1/9/2014.

Author(s): Horne, Rosemary SC; Roy, Bhaswati; Walter, Lisa M; Biggs, Sarah N; Tamanyan, Knarik; Weichard, Aidan; Nixon, Gillian M; Davey, Margot J; Ditchfield, Michael; Harper, Ronald M; Kumar, Rajesh | Abstract: Study objectivesChildren with sleep-disordered breathing (SDB) exhibit behavioral, cognitive, and autonomic deficits, suggestive of neural injury. We assessed whether the tissue alterations resulted from acute or chronic processes, and whether alterations correlated with disease severity.MethodsBrain tissue integrity was examined with mean diffusivity (MD) (3.0 T scanner) in 20 nonsnoring controls (mean age ± SEM, 12.2 ± 0.6 years; 10 males) and 18 children with SDB (12.3 ± 0.7 years; 11 males). Sleep, cognitive, and behavioral measures were compared between groups following overnight polysomnography using Student's t tests. Whole-brain MD maps were realigned and averaged, normalized, smoothed, and compared between groups using ANCOVA (covariates: age, gender, and socioeconomic status). Partial correlations were calculated between whole-brain smoothed MD maps and obstructive apnea-hypopnea indices (OAHIs).ResultsAge, gender, and sleep variables did not differ between groups. The SDB group showed higher OAHIs, body mass indices, and systolic blood pressure. Significantly reduced MD values (acute changes) appeared in the hippocampus, insula, thalamus, temporal and occipital cortices, and cerebellum, but were increased (chronic damage) in the frontal and prefrontal cortices in the SDB group over controls. Both positive and negative correlations appeared with extent of tissue changes and disease severity. Externalizing and Total Problem Behaviors were significantly higher in children with SDB. Verbal, performance, and total IQ scores trended lower, and behavioral scores trended higher.ConclusionsPediatric SDB is accompanied by predominantly acute brain changes in areas that regulate autonomic, cognitive, and mood functions, and chronic changes in frontal cortices essential for behavioral control. Interventions need to be keyed to address acute vs chronic injury.

The prevalence of obese children with sleep disordered breathing (SDB) is increasing. Obesity and SDB are independent cardiovascular risk factors, of which arterial stiffness is an early sign. Pulse wave velocity (PWV), is a marker of arterial stiffness and central systolic blood pressure (cSBP) is a better predictor of cardiovascular outcome than peripheral blood pressure. Therefore, we aimed to determine PWV and cSBP in overweight/obese or normal weight children with sleep disordered breathing (SDB), and non-snoring normal weight controls.Children (3-18 y) with SDB (overweight/obese [BMI z-scores ≥ 1.04], n = 48; normal weight n = 44) referred for clinical assessment of SDB and normal weight non-snoring controls recruited from the community (n = 38) underwent overnight polysomnography. PWV was calculated using photoplethysmography. cSBP was calculated using applanation tonometry in a subset of children older than 8 y (n = 55) who had usable waveforms.Overweight/obese SDB group had higher PWV (mean cm/s (95% CI); wake: 366 (355-380); sleep: 340 (324-357)), than the normal-weight SDB group (wake: 257 (247-267), p = 0.002; sleep: 255 (242-269), p = 0.005), and non-snoring controls (wake: 238 (226-249), p = 0.002; sleep: 235 (220-250), p 0.001). The normal-weight SDB group had higher PWV than controls (p = 0.03). Overweight/obese children with SDB had higher cSBP (105 (100-110) mmHg) compared with the normal weight children with SDB (96 (90-102)) and the non-snoring controls (97 (91-104); p 0.05 for both).This study suggests that overweight/obesity substantially worsens the cardiovascular sequelae of SDB, highlighting the imperative to treat obesity and SDB in children early in order to reduce future cardiovascular disease risk.

Sleep disordered breathing (SDB) in preschool-aged children is common, but long-term outcomes have not been investigated. We aimed to compare sleep and respiratory parameters in preschool children to examine the effects of treatment or non-treatment after 3 years.Children (3-5 years) diagnosed with SDB (n = 45) and non-snoring controls (n = 30) returned for repeat overnight polysomnography (39% of original cohort), 3 years following baseline polysomnography. Children with SDB were grouped according to whether they had received treatment or not. SDB resolution was defined as an obstructive apnea hypopnea index (OAHI) ≤ 1 event/h, no snoring detected on polysomnography and habitual snoring not indicated by parents on questionnaire.Fifty-one percent (n = 23) of the children with SDB were treated. Overall, SDB resolved in 49% (n = 22), either spontaneously (n = 8) or with treatment (n = 14). SDB remained unresolved in 39% (n = 9) of those treated and 64% (n = 14) of the children who were untreated. Two of the non-snoring controls developed SDB at follow-up. The treated group had significantly lower OAHI (p0.01), respiratory disturbance index (p0.001), total arousal and respiratory arousal indices (p0.01 for both) at follow-up compared with baseline. There were no differences between studies for the untreated group.Although treatment resulted in an improvement in indices related to SDB severity, 39% had SDB 3 years following diagnosis. These findings highlight that parents should be made aware of the possibility that SDB may persist or recur several years after treatment. This is relevant regardless of the severity of SDB at baseline and the treatment given.

Objective: Sleep is critical for adolescent health and well-being. However, there are a limited number of validated self-report measures of sleep for adolescents and no well-validated measures of sleep that can be used across middle childhood and adolescence. The Children’s Report of Sleep Patterns (CRSP) has been validated in children aged 8–12 years. The purpose of this study was to examine the psychometric properties of the CRSP, a multidimensional, self-report sleep measure for adolescents. Methods: The participants included 570 adolescents 13–18 years, 60% female, recruited from pediatricians’ offices, sleep clinics, children’s hospitals, schools, and the general population. A multi-method, multireporter approach was used to validate the CRSP. Along with the CRSP, a subset of the sample completed the Adolescent Sleep Hygiene Scale (ASHS), with a different subset of adolescents undergoing polysomnography. Results: The CRSP demonstrated good reliability and validity. Group differences on the CRSP were found for adolescents presenting to a sleep or medical clinic (vs. a community sample), for older adolescents (vs. younger adolescents), for those who regularly napped (vs. infrequently napped), and for those with poor sleep quality (vs. good sleep quality). Self-reported sleep quality in adolescents was also associated with higher apnea–hypopnea index scores from polysomnography. Finally, the CRSP Sleep Hygiene Indices were significantly correlated with indices of the ASHS. Conclusions: The CRSP is a valid and reliable measure of adolescent sleep hygiene and sleep disturbances. With a parallel version for middle childhood, the CRSP likely provides clinicians and researchers the ability to measure self-reported sleep across development. Refereed/Peer-reviewed

This study aimed to examine slow wave activity (SWA), a marker of homeostatic regulation, as a potential mechanism linking sleep disordered breathing (SDB) with executive dysfunction in children. Executive function domains of working memory, spatial planning, information processing, and sustained attention were assessed using the Cambridge Neuropsychological Test Automated Battery (CANTAB) in children (N = 40; 5–12 years) referred for clinical diagnosis of SDB. Polysomnography records of non-snoring, age-matched controls (N = 34) were retrospectively examined for comparison of SWA. Power spectral analysis of the delta wave determined SWA. Group differences in sleep, respiratory, and SWA outcomes were examined. Mean CANTAB scores were compared to standardized norms and correlated against SWA. Children with SDB showed increased SWA compared to non-snoring controls and scored

Up to 50% of overweight/obese children have obstructive sleep apnea (OSA) compared to up to 6% of normal weight children. We compared cardiovascular variables between normal weight and overweight/obese children with and without OSA, and controls.Seventy-four referred children and 24 normal weight non-snoring controls (8-18 years) were recruited. Referred children were grouped according to their obstructive apnea hypopnea index (OAHI): OSA (1 event/h) or primary snoring (PS ≤ 1 event/h) and whether they were normal weight (BMI z-score1.04) or overweight/obese (BMI z-score ≥ 1.04). Wake blood pressure (BP), heart rate (HR), and pulse transit time (PTT, an inverse continuous surrogate measure of blood pressure) during sleep were recorded.Wake BP was higher in the overweight/obese OSA group than in the control, normal weight PS, and overweight/obese PS groups (p 0.05 for all). During sleep, BP, and HR were elevated in the overweight/obese OSA group compared to those in non-snoring controls (p 0.05). More children who were overweight/obese had reduced BP and HR dipping from wake to sleep than normal weight children. The BMI z-score predicted HR and PTT when asleep and both age and BMI z-score predicted BP when awake.This study showed that BMI has both combined and independent effects on BP and HR in children with OSA. We have previously shown that treatment of OSA reduces BP and suggest that treatment of OSA in the growing number of overweight/obese children may improve cardiovascular outcomes.

This study aimed to determine whether overweight and obesity increased the detrimental effects of pediatric sleep-disordered breathing (SDB) on cognition, behavior, mood, and quality of life.Children and adolescents (8-16 years) with clinically diagnosed SDB were categorized into two groups: healthy weight (Body Mass Index (BMI) z-score1.04, N = 11) and overweight/obese (BMI z-score ≥ 1.04, N = 10). Age-matched healthy weight, non-snoring controls (N = 25) were recruited from the community. All participants underwent overnight laboratory polysomnography (PSG). Cognitive, behavioral, and quality of life assessments were conducted in the home following the PSG. Analysis of Covariance (ANCOVA) was used to assess group differences in cognitive outcomes, controlling for socio-economic status. Kruskal-Wallis ANOVA was used to determine group differences in behavior and quality of life. Where group differences were found, hierarchical linear regressions determined the effect of weight on outcomes.Children with SDB had significantly poorer behavior and quality of life than controls, with overweight/obese children with SDB having the greatest dysfunction. No group differences were found in cognitive outcomes. The obstructive apnea hypopnea index (OAHI) was a significant predictor of withdrawn behavior (ROverweight and obesity comorbid with SDB increase the risk of externalizing behaviors such as aggression but do not affect other behavioral associates of SDB such as inattention and school functioning.

Objective: Sleepwalking is common in children, however, the relationship between sleepwalking, bedtime routine and daytime problems is poorly understood. We assessed the prevalence of parent reported sleepwalking in school children, and its relationship with broader sleep and daytime difficulties. Methods: Parents of 1814 children aged 5 to 10 years reported on child sleepwalking, other sleep behavior, emotional and daytime behavioral functioning. Results: Parents reported that 10.5% of children had sleepwalked in the previous week. There were no sex differences in sleepwalking prevalence, however middle children were reported to sleepwalk more than other children. Sleepwalking was associated with more problems of bedtime routine, bedtime anxiety, and daytime tiredness, as well as more sleep terrors, sleep talking, disordered sleep breathing symptoms, restless sleep and bruxism; however, these correlations were very small. Sleepwalkers also had significantly more emotional problems, conduct problems, and hyperactivity. Post hoc analyses showed that after controlling for sleep disordered breathing and sleep terrors, sleepwalking no longer contributed to the prediction of emotional, conduct, or hyperactivity problems, or morning tiredness. Results for the relationship between sleep instability and sleepwalking were mixed. Conclusions: Frequent sleepwalking is common in children and is associated with a range of sleep and behavior problems. However, behavioral and emotional problems associated with sleepwalking are accounted for by comorbid sleep disorders. Risk for other sleep related problems and impact on daytime functioning in children who sleepwalk warrant assessment and treatment. Similarly, children presenting with behavioral concerns should be assessed for sleep Refereed/Peer-reviewed

In 2007 the American Academy of Sleep Medicine (AASM) published polysomnography (PSG) scoring guidelines, which were updated in 2012. A key change in terms of scoring respiratory events in children was the threshold for reduction in airflow (50% vs 30%) for the definition of hypopnea. This study aimed to determine the impact of different scoring rules on the assessment of severity of obstructive sleep apnea (OSA) in children.Forty-two children (mean age 4.3 y, 16 F) underwent PSG. An obstructive apnea-hypopnea index (OAHI) was determined using three scoring rules: (1) ATS 1996 rules with minor modifications (modified ATS 1996); (2) AASM 2007 rules (AASM 2007); and (3) AASM 2007 rules with respiratory event related arousals included in the OAHI (AASM+RERA).The AASM 2007 OAHI (median 0.4 events/h, range 0, 14) was lower than the modified ATS 1996 OAHI (median 0.8 range 0, 26.1, p0.001), underestimating severity of disease in 24% of cases. The AASM+RERA OAHI (median 0.8, range 0, 19.1) was also lower than the modified ATS 1996 OAHI (p = 0.02), but the difference was not clinically significant except at very high OAHIs.The AASM 2007 rules lead to a lower OAHI and lesser OSA severity when compared to the previous standard. Inclusion of RERAs in the AASM 2007 OAHI leads to a comparable OAHI to the previous rules. Given that morbidity has been demonstrated even in mild OSA, these results support the inclusion of events with a reduction in airflow of less than 50% as included in the updated AASM rules in 2012.

Obstructive sleep apnea (OSA) is associated with autonomic dysfunction in adults and school-aged children; however, this association has not been investigated in preschool children. We aimed to analyze heart rate variability (HRV) and catecholamine levels in preschool children with OSA.One hundred and forty-two snoring children aged 3-5years and 38 nonsnoring control group children underwent overnight polysomnography (PSG). Nocturnal urinary catecholamines were measured in 120 children. Children were grouped according to their obstructive apnea-hypopnea index (OAHI) (control [no snoring], OAHI⩽1event/h; primary snoring, OAHI⩽1event/h; mild OSA OAHI1⩽5events/h; moderate to severe [MS] OSA, OAHI5events/h). The HRV parameters for each child were averaged during rapid eye movement (REM) and non-REM (NREM) sleep.During stable sleep, low-frequency (LF) HRV was similar between groups. High-frequency (HF) HRV was higher in the MS OSA group compared with the control group during all sleep stages (NREM sleep stages 1 and 2 [NREM1/2], 4234±523ms(2) vs 2604±457ms(2); NREM sleep stages 3 and 4 [NREM3/4], 4152±741ms(2) vs 3035±647ms(2); REM, 1836±255ms(2) vs 1456±292ms(2); P.01 for all). The LF/HF ratio was lower in the MS OSA group compared with the control group (NREM1/2, 0.4±0.06 vs 0.7±0.05; NREM3/4, 0.3±0.06 vs 0.4±0.05; REM, 0.8±0.1 vs 1.3±0.1; P.01 for all). Catecholamine levels were not different between groups.In preschool children, OSA is associated with altered HRV, largely due to the HF fluctuations in heart rate (HR) which occur during respiratory events and are still evident during stable sleep. The preschool age may represent a window of opportunity for treatment of OSA before the onset of the severe autonomic dysfunction associated with OSA in adults and older children.

Little is known about the pediatric population at an increased risk of restless legs syndrome (RLS) and periodic limb movement disorder (PLMD). Polysomnographic data from the Caffeine for Apnea of Prematurity-Sleep (CAPS) study showed a high prevalence of elevated periodic limb movement index (PLMI) in a cohort of ex-preterm children, but the clinical importance of this finding, such as association with RLS, is unknown. We hypothesized that ex-preterm children would have a high prevalence of RLS and PLMD.Ex-preterm children enrolled in CAPS, now aged 5-12 years, completed home polysomnography (PSG) and standardized questionnaires. A diagnosis of RLS or PLMD was established by participants meeting the International Classification of Sleep Disorders, 3rd edition, criteria based on questionnaires and polysomnograms. The clinically available serum ferritin levels were assessed.In total, 167 participants underwent polysomnography and completed all questionnaires. The overall prevalence of RLS was 14/167 (8.4%). An additional 13 subjects (7.8%) were found to have PLMD. Of the 26 participants who had PLMI 5/h, seven (26.9%) had RLS and 13 (50%) had PLMD. The serum ferritin levels were50 mcg/L (range -38.4) for all eight participants referred for testing.Children with a history of prematurity have a high prevalence of RLS, particularly those with elevated periodic limb movements. Iron deficiency likely contributes to RLS and PLMD symptoms in this population. Clinicians evaluating ex-preterm children with sleep disturbances should evaluate for RLS and PLMD. Further studies including serum ferritin evaluation are required to confirm these findings.

Background It has been suggested that impaired dissipation of slow-wave activity (SWA) in children with sleep-disordered breathing (SDB) may be a potential mechanism for daytime dysfunction. We aimed to examine whether resolution of SDB resulted in normalisation of SWA dissipation and whether this was associated with improved cognition and behaviour. Methods Children (aged 3–6 y) diagnosed with SDB and age-matched non-snoring control children were followed up for 3 y after a baseline study. At the follow-up, children were categorised into control (N = 13), resolved SDB (N = 15) and unresolved SDB (N = 14). Delta activity on the electroencephalogram over the sleep period was used to calculate SWA and a battery of cognitive assessments and behaviour questionnaires were conducted at both time points. Results There was no change in the average SWA between the baseline and follow-up and no differences between the groups. Cognitive and behavioural performance in the resolved group did not improve to control levels. However, decreased SWA at the beginning of the sleep period (β = −0.04, p = 0.002) and a decrease in obstructive apnoea–hypopnoea index (β = −2.2, p = 0.022) between the baseline and follow-up predicted improvements in measures of sustained attention. Increased SWA at the beginning of the sleep period between the baseline and follow-up predicted worsening of externalising behaviour (β = 0.02, p = 0.039). Conclusions This study suggests that resolution of SDB is not associated with changes in the dissipation of SWA. However, the association between decreases in SWA and improvements in cognitive and behavioural outcomes suggest that irrespective of disease, children whose quantitative sleepiness improves have improved attention and reduced externalising behaviours.

Background: Few studies have examined self-reported sleepwalking in older adolescents. The aim of this study was to examine the prevalence rates of sleepwalking in a one-month self-report period in Australian adolescents. Methods: Participants were 532 Australian adolescents in their final two years of secondary school. Results: The prevalence of sleepwalking in the one-month self-report period was 2.9% (95% confidence interval (CI) 1.47–4.33) in this sample—1% reported sleepwalking at least once a week in the previous month. A significant proportion (17.5%) of the participants was unsure if they had sleepwalked. Conclusion: The results provide data on the self-reported prevalence rate of sleepwalking in older adolescents. Compared with the population data, this rate falls within the confidence intervals of child and adult prevalence rates of sleepwalking and is consistent with a decline in sleepwalking from childhood and adulthood. Further research is needed to explore how adolescents know they sleepwalk to understand the reliability of self-report measures. Refereed/Peer-reviewed

Sleep-disordered breathing (SDB) has been associated with impaired cognitive and behavioral function in school children; however, there have been limited studies in preschool children when the incidence of the disorder peaks. Thus, the aim of this study was to compare cognitive and behavioral functions of preschool children with SDB to those of non-snoring control children.A clinical sample of 3-5 year-old children (primary snoring [PS], n=60; mild obstructive sleep apnea syndrome [OSAS], n=32; moderate/severe [MS] OSAS, n=24) and a community sample of non-snoring control children (n=37) were studied with overnight polysomnography. Cognitive performance and behavioral information were collected.Children with PS and mild OSAS had poorer behavior than controls on numerous measures (p.05-p.001), and on some measures they had poorer behavior than the MS OSAS group (p.05). In contrast, all groups performed similarly on cognitive assessment. Outcomes related more to sleep than respiratory measures.SDB of any severity was associated with poorer behavior but not cognitive performance. The lack of significant cognitive impairment in this age group may have identified a "window of opportunity" where early treatment may prevent deficits arising later in childhood.

Objectives Current recommendations for healthy sleep in school-aged children are predominantly focused on optimal sleep duration (9-11 h). However, given the importance of routine for circadian health, the stability of sleep/wake schedules may also be important, especially for daytime behavioral functioning. We examined the relationship between short sleep duration, sleep schedule instability and behavioral difficulties in a community sample of Australian children. Methods Children, aged 5-10 years (N = 1622), without chronic health or psychological conditions, were recruited from primary schools in Adelaide, South Australia. A parent-report questionnaire was used to assess sleep/wake behavior. Behavioral functioning was assessed using the Strengths and Difficulties Questionnaire. Results Most children met sleep duration recommendations with approximately 5% reporting 12 h. Weekly variability of bed and rise times >1 h were reported in up to 50% of children. Multinomial regression analysis revealed sleep duration 60 min, and bed and rise time variability > 60 min significantly increased the risk of scoring in the 95th percentile for behavioral sub-scales. Conclusions Inconsistent sleep schedules were common and, similar to short sleep duration, were associated with behavioral difficulties. Considering the lack of study in this area, further research is needed for the development of new recommendations, education and sleep health messages. Refereed/Peer-reviewed

The study aim was to determine the effects of sleep restriction (5 h of time in bed) compared with 10 h of sleep opportunity on declarative memory function in young children. Fourteen girls attended a sleep laboratory for three nights: adaptation, control, and restriction. The Auditory Verbal Learning Task (AVLT) measured declarative memory performance before and after sleep. No significant differences were found in performance between control and sleep restriction. Performance deteriorated in all delayed recall trials, with significant differences found between pre- and post-sleep trials in both conditions. Memory function in children, as measured by the AVLT, is not affected by acute sleep restriction.

Objective As feelings of alertness are reported to be highly correlated with performance perception, the objective of this study was to determine whether caffeine, a common countermeasure to driver sleepiness, affected a sleepy driver's ability to monitor his or her simulated driving performance. Methods Twelve healthy young adults (six males, six females) participated in three counterbalanced, blinded, daytime conditions: control [9 h time in bed (TIB)], 100 mg caffeine (4 h TIB), and placebo (4 h TIB). Driving performance was measured through lane drift on a series of 30-min simulated driving sessions. Subjective sleepiness and perception of driving performance were measured at 5-min intervals during driving sessions via the Karolinska Sleepiness Scale and a corresponding perception scale. Results Sleep restriction had a significant detrimental effect on driving performance and subjective measures. Caffeine resulted in significant improvements across all measures. Subjective measures were found to be significantly correlated after sleep restriction and prior to caffeine. Correlations between actual and perceived performance were nonsignificant across all conditions. Conclusions The strong correlation between subjective measures supports the postulation that sleepiness is used as a cue for performance prediction when sleep restricted. The relationship between perceived and actual performance after fatigue countermeasures remains inconclusive. Further research, addressing limitations, is needed.

Sleep disordered breathing (SDB) is common in children, resulting in extensive waiting lists for specialist clinics. There is an urgent need for a valid method of triaging patients and the OSA-18, a disease-specific tool, is an attractive candidate for this role. We aimed to examine the OSA-18 as a measurement tool in detail and to determine whether the score or aspects of it could be used as a screening tool for SDB in children. Retrospective analysis of 582 children (6 months to 16.4 years)—216 underwent overnight PSG and 366 overnight oximetry. Confirmatory factor analysis (CFA) and exploratory factor analysis (EFA) were conducted. Receiver operating characteristic curve analysis assessed the diagnostic accuracy of the factors for the presence of OSA. Rasch analysis was used to assess the structure of the items (1–18) and categories of response (Likert scale). The CFA with a forced five-factor structure, revealed three factors with Eigenvalues >1, and explained 73.7 % of the variance. EFA resulted in a two-factor structure, explaining 60.3 % of the variance. Assessment of sensitivity and specificity showed a high false-positive rate, irrespective of the factor structure tested. Rasch analysis showed poor discrimination between adjacent categories on the Likert scale. This study confirmed that the predictive value of the OSA-18 for SDB severity is weak. Some questions perform better than others statistically, and the seven categories of response introduce significant statistical noise, raising the possibility that modification of the OSA-18 may improve its performance in the prediction of OSA severity.

To compare sleep/wake patterns in children born preterm in Australia vs Canada and determine cultural differences in the relationship between parental perception of sleep and actual sleep behaviors.Australian and Canadian children born preterm were recruited from the Caffeine for Apnea of Prematurity trial (n = 188, 5-12 y) and underwent 14 days actigraphy monitoring. Parents completed the National Sleep Foundation 2004 Sleep in America questionnaire. Cross-cultural differences in sleep characteristics assessed by actigraphy and parent-reported questionnaire were examined. Correlational analyses determined the associations between parental perceptions of child sleep need and sleep behavior.Actigraphy showed preterm children obtained, on average, 8 h sleep/night, one hour less than population recommendations for their age. There was no difference in total sleep time (TST) between Australian and Canadian cohorts; however, bed and wake times were earlier in Australian children. Bedtimes and TST varied by 60 minutes from night to night in both cohorts. Parent-reported child TST on the National Sleep Foundation questionnaire was 90 minutes longer than recorded by actigraphy. Both bedtime and TST on weekdays and weekends were related to parental perception of child sleep need in the Australian cohort. Only TST on weekdays was related to parental perception of child sleep need in the Canadian cohort.This study suggests that short sleep duration and irregular sleep schedules are common in children born preterm. Cultural differences in the association between parental perception of child sleep need and actual sleep behaviors provide important targets for future sleep health education.

This study aims to determine whether demographic or clinical factors predict obstructive sleep apnoea (OSA) severity in Australian children.Demographic details and medical histories of 301 Australian children (3-17 years old) referred for assessment of OSA were examined retrospectively. Children underwent overnight polysomnography and were classified as having primary snoring (PS) (obstructive apnoea hypopnoea index (OAHI) ≤ 1 event per hour; n = 150), mild OSA (1 OAHI ≤ 5 events per hour; n = 76) or moderate/severe (MS) OSA (OAHI 5 events per hour; n = 75). Information obtained from parent-report questionnaire determined the predictive value of the following factors for determining OSA severity: gender, ethnicity, body mass index, asthma and/or allergic rhinitis, socio-economic status and parental smoking status (mother/father/both). Chi-squared analyses were used to compare the distribution of the demographic and clinical factors across the three groups. Statistically significant risk factors were subsequently entered into logistic regression analysis.Ethnicity and parental smoking were significant risk factors for MS OSA. Children with non-Caucasian ethnicity were 36% more likely than Caucasian children to be diagnosed with MS OSA than PS (P = 0.002). Children with fathers who smoked were 53% more likely to have MS OSA than PS compared with those with fathers who did not smoke (P = 0.008). Obesity was associated with OSA severity in primary school-aged children only. Gender, socio-economic status and history of asthma and/or allergic rhinitis were not risk factors.Non-Caucasian ethnicity, paternal smoking and obesity in older children were associated with an increased risk of polysomnography-confirmed MS OSA in Australian children.

Sleep-disordered breathing (SDB) prevalence peaks in preschool children and is associated with deficits in cardiovascular functioning during sleep. No long-term studies have investigated the effects of SDB resolution in mitigating these outcomes. We hypothesized that following 3 years, normalization of alterations to heart rate (HR), pulse transit time (PTT), heart rate variability (HRV), and urinary catecholamines identified at the initial diagnosis would be associated with resolution of SDB. Forty-five children with SDB and 28 non-snoring controls underwent polysomnography at baseline (3–5 years) and follow-up (6–9 years). Children were classified into control, resolved, and unresolved SDB. Resolution was defined as an obstructive apnea–hypopnea index (OAHI) ≤1 event/h, no snoring on polysomnography (PSG), or indicated by parents. PTT is an inverse surrogate measure of blood pressure change. HRV was assessed using power spectral analysis. There was no change in PTT or HR between studies for any group. Our HRV data suggest reduced parasympathetic activity in children whose SDB resolved and increased parasympathetic activity in children whose SDB remained the same or worsened at follow-up. We identified a significant correlation between low frequency power and urinary dopamine and adrenaline levels at follow-up in the unresolved group, suggesting increased sympathetic activity in children with unresolved SDB. Our findings suggest an association between resolution of SDB and normalization of HRV in the long term in these preschool children and an augmented sympathetic activity in the children with residual SDB. This highlights the autonomic impact of SDB in young children and the importance of detection and treatment.

Study objectives Few studies have examined the validity of actigraphy in school-aged children. The objective of this study was to examine the validity of a commonly used actigraph compared to polysomnography (PSG) in a sample of children age 5 to 12 y born prematurely, sleeping in their natural home environment. Methods 148 children born preterm (85 boys and 63 girls), ages 5-12 y (mean = 9.3 y, standard deviation = 2.0) wore the Philips Respironics Actiwatch-2 for 1 night concurrently with comprehensive, ambulatory PSG in the child's home. Sleep outcome variables were sleep onset latency, total sleep time (TST), and sleep efficiency. Epoch-by-epoch comparisons were used to determine sensitivity, specificity, and accuracy. Secondary analyses examined differences between children with no sleep issues, obstructive sleep apnea syndrome, and periodic limb movements in sleep (PLMS). Results Actigraphy significantly underestimated TST (30 min) and sleep efficiency (5%). Actigraphy underestimated or overestimated sleep onset latency by at least 10 min for a third of the children. Sensitivity and accuracy were good at 0.88 and 0.84, respectively, whereas specificity was lower at 0.46. Differences between actigraphy and PSG for TST and sleep efficiency were greatest for children with PLMS. Conclusions This study adds to the small existing literature demonstrating the validity of actigraphy in middle childhood. Although actigraphy shows good sensitivity (ability to detect sleep), specificity (ability to detect wake) is poor in this age group. Further, the results highlight the importance of considering whether a child has PLMS when interpreting actigraphic data, as well as the difficulties in accurately capturing sleep onset latency with actigraphy.

Childhood sleep disordered breathing (SDB) presents as isolated respiratory events or episodes of consecutive repetitive events. We hypothesized that the surge in blood pressure (BP) and heart rate (HR) would be greater at the termination of events during episodes of repetitive events than following isolated events.% change in HR and pulse transit time (PTT; inverse surrogate of BP) were calculated from the last half of an event to: (i) between successive repetitive events; (ii) termination of the last repetitive event; (iii) event termination for isolated events.69% of the children exhibiting both isolated and repetitive events had more repetitive than isolated events. %HR change between repetitive events (27 ± 1%) was greater than at event termination for isolated events (17 ± 1%; P0.001). %PTT change at the termination of the last repetitive event (-8 ± 2%) was greater than at the termination of isolated events (-2 ± 2%; P0.05).Episodes of repetitive respiratory events evoke a greater acute cardiovascular response, including surges in BP and HR between events, than do isolated events. Given that the majority of respiratory events in preschool children occur as repetitive episodes, this finding should be taken into account when assessing the impact of respiratory events for a given child.

Rationale: Apnea of prematurity is a common condition that is usually treated with caffeine, an adenosine receptor blocker that has powerful influences on the central nervous system. However, little is known about the long-term effects of caffeine on sleep in the developing brain.Objectives: We hypothesized that neonatal caffeine use resulted in long-term abnormalities in sleep architecture and breathing during sleep.Methods: A total of 201 ex-preterm children aged 5–12 years who participated as neonates in a double-blind, randomized, controlled clinical trial of caffeine versus placebo underwent actigraphy, polysomnography, and parental sleep questionnaires. Coprimary outcomes were total sleep time on actigraphy and apnea–hypopnea index on polysomnography.Measurements and Main Results: There were no significant differences in primary outcomes between the caffeine group and the placebo (adjusted mean difference of −6.7 [95% confidence interval (CI) = −15.3 to 2.0 min]; P = 0.13 for actigraphic total sleep...

Although unattended ambulatory polysomnography (PSG) is frequently performed in adults, few studies have been performed in children. The objective of this study was to evaluate the feasibility of comprehensive, ambulatory PSG, including electroencephalography, in school-aged children in the home environment.A total of 201 children, born premature with birth weights of 500-1,250 grams, currently aged 5-12 years and living in Canada and Australia, underwent unattended ambulatory PSG.PSG was initially technically satisfactory in 183 (91%) cases. Fourteen studies were satisfactory when repeated, resulting in an overall satisfactory rate of 197 (98%). Artifact-free signals were obtained for ≥ 75% of recording time in more than 92% of subjects, with the exception of nasal pressure, which was satisfactory for ≥ 75% of recording time in only 67% of subjects. However, thermistry signals were satisfactory for ≥ 75% of recording time in 92% of subjects, and some measure of airflow was present for ≥ 75% of recording time in 96% of subjects. Children slept very well, with a long total sleep time (534 ± 73 [mean ± SD] minutes), high sleep efficiency (92% ± 5%), and low arousal index (9 ± 3/h). Parents and children reported a high rate of satisfaction with the study.This large, international study has shown that comprehensive, unattended, ambulatory PSG is feasible, technically adequate and well-tolerated in school-aged children when performed under research conditions. Further studies regarding the cost efficacy of this approach, and generalizability of the findings to a clinical population, are warranted.

Purpose: The aim of this study was to assess the construct validity and clinical application of the Pediatric Sleep Survey Instrument (PSSI) as a tool to screen for sleep disordered breathing (SDB) in children. Methods: Polysomnography (PSG) outcomes and PSSI subscale scores were compared between a clinical cohort (N =87, 5–10 years, 62 M/25 F) and a nonsnoring community sample (N =55, 5–10 years, 28 M/27 F). Group comparisons assessed the ability of the PSSI subscales to discriminate between the clinical and community cohorts. Receiver operating characteristic (ROC) curves assessed construct validity, with the Apnea/Hypopnea Index (AHI) >5 events/h, OSA-18 score >60, and Pediatric Daytime Sleepiness Scale (PDSS) above the 70th percentile as the target references. Results The clinical group had more respiratory events, respiratory-related arousals, fragmented sleep, and lower oxygen saturation nadir than the community group (p 5 events/h (area under the curve (AUC)=0.7), an OSA- 18 score >60 (AUC=0.7), and a PDSS score in the 70th percentile (AUC=0.8). The Morning Tiredness subscale accurately predicted a PDSS score in the 70th percentile (AUC=0.8). A cutoff score of 5 on the SDB subscale showed a sensitivity of 0.94 and a specificity of 0.76, correctly identifying 77 and 100 % of the clinical and community cohorts, respectively. Conclusion: The PSSI Sleep Disordered Breathing subscale is a valid tool for screening SDB and daytime sleepiness in children aged 5–10 years. Refereed/Peer-reviewed

Sleep disordered breathing (SDB) is common in children and describes a continuum of nocturnal respiratory disturbance from primary snoring (PS) to obstructive sleep apnoea (OSA). Historically, PS has been considered benign, however there is growing evidence that children with PS exhibit cognitive and behavioural deficits equivalent to children with OSA. There are two popular mechanistic theories linking SDB with daytime morbidity: hypoxic insult to the developing brain; and sleep disruption due to repeated arousals. These theories apply well to OSA, but children with PS experience neither hypoxia nor increased arousals when compared to non snoring controls. So what are we missing? This review summarises the literature examining daytime morbidity in children with PS and discusses the current debates surrounding this relationship. Specifically, questions exist as to the sensitivity of our standard assessment techniques to measure subtle hypoxia and arousal. There is also a suggestion that the association between PS and daytime morbidity may not be mediated by nocturnal respiratory disturbance at all, but by a number of other comorbid, but perhaps unrelated factors. As approximately 70% of children with SDB are diagnosed with PS, but are rarely treated, a paradigm shift in the investigation of PS may be required.

OBJECTIVES: To characterize health-related quality of life (QOL) in preschool children with sleep disordered breathing (SDB) and their families compared with nonsnoring control patients in the community. It was hypothesized that children with SDB and their families would have poorer QOL than control children, that a relationship would be found between SDB severity and QOL, and that even children with mild SDB and their families would have reduced QOL. PARTICIPANTS AND METHODS: A clinical sample of preschool children (3-5 y) with SDB diagnosed by gold standard polysomnography (primary snoring, PS = 56, mild obstructive sleep apnea, OSA = 35, moderate/severe OSA = 24) and control children recruited from the community (n = 38) were studied. Parents completed health-related QOL and parenting stress questionnaires. RESULTS: Children and families in the PS and mild OSA groups had consistently poorer QOL than control children (both P < 0.05-0.001), based on parent ratings, and parents of children with PS had elevated stress ratings relative to control children (P < 0.05-0.001). The moderate/severe OSA group differed from the control group on select measures of parent and family QOL (worry, P < 0.001 and total family impact, P < 0.05). CONCLUSIONS: Our findings demonstrate that sleep disordered breathing is associated with reduced quality of life in preschool children and their families. These results support previous quality of life findings in older children and in samples with broader age ranges. Furthermore, clinically referred preschool children with mild forms of sleep disordered breathing may be at greatest risk.

Objective Sleep-disordered breathing (SDB) is associated with reduced nocturnal dipping of blood pressure (BP) and sleep disruption in adults, and these features confer an increased risk of cardiovascular events. As SDB prevalence in children peaks during the preschool years, we investigated nocturnal dipping and sleep fragmentation in preschool children with SDB. Methods Children (3–5 years; n = 163) grouped by obstructive apnoea hypopnoea index (OAHI): control, no snoring history and OAHI ⩽1 event/h; primary snoring, OAHI ⩽1 event/h; mild SDB, >1–⩽5 events/h; moderate–severe SDB, >5 events/h. Pulse transit time (PTT), an inverse continuous indicator of BP changes, and heart rate (HR) during total sleep time and the first period of rapid eye movement (REM), non-REM (NREM)1/2 and NREM3/4 sleep were expressed as percentage change from wake before sleep onset. The sleep fragmentation index (SFI) was calculated as the number of sleep stage transitions or awakenings per hour of sleep. Results There were no group differences in the change in PTT or HR from wake to total sleep time or to individual sleep stages or in the proportion of children in the quartile with the smallest change in PTT during total sleep. Children with moderate–severe SDB had higher SFI than primary snoring (PS) or mild SDB groups (p Conclusions In contrast to adults, nocturnal dipping is preserved in young children with SDB, despite increased sleep fragmentation. As there is evidence that nocturnal dipping is similarly preserved at the school age, childhood may pose a window of opportunity for resolution of SDB when the cardiovascular effects are less marked.

Study Objectives: In adults and older children, snoring and obstructive sleep apnea (OSA) are associated with elevated blood pressure (BP). However, BP has not been assessed in preschool children, the age of highest OSA prevalence. We aimed to assess overnight BP in preschool children with snoring and OSA using pulse transit time (PTT), an inverse continuous indicator of BP changes. Design: Overnight polysomnography including PTT. Children were grouped according to their obstructive apnea-hypopnea index (OAHI); control (no snoring, with OAHI of one event or less per hour), primary snoring (OAHI one event or less per hour), mild OSA (OAHI greater than one event to five events per hour) and moderate-severe OSA (OAHI more than five events per hour). Setting: Pediatric sleep laboratory. Patients: There were 128 clinically referred children (aged 3-5 years) and 35 nonsnoring community control children. Measurement and Results: PTT was averaged for each 30-sec epoch of rapid eye movement (REM) or nonrapid eye movement (NREM) sleep and normalized to each child's mean wake PTT. PTT during NREM was significantly higher than during REM sleep in all groups (P < 0.001 for all). During REM sleep, the moderate-severe OSA group had significantly lower PTT than the mild and primary snoring groups (P < 0.05 for both). This difference persisted after removal of event-related PTT changes. Conclusions: Moderate-severe OSA in preschool children has a significant effect on pulse transit time during REM sleep, indicating that these young children have a higher baseline BP during this state. We propose that the REM-related elevation in BP may be the first step toward develop- ment of daytime BP abnormalities. Given that increased BP during childhood predicts hypertension in adulthood, longitudinal studies are needed to determine the effect of resolution of snoring and/or OSA at this age.

Pulse transit time has been proposed as a surrogate measure of systolic arterial pressure, as it is dependent upon arterial stiffness. Past research has shown that pulse transit time has a significant inverse relationship to systolic arterial pressure in adults; however, studies in children are limited. This study aimed to explore the relationship between systolic arterial pressure and pulse transit time in children during sleep. Twenty-five children (13.1 ± 1.6 years, 48% male) underwent overnight polysomnography (PSG) with a simultaneous recording of continuous systolic arterial pressure and photoplethysmography. Pulse transit time was calculated as the time delay between the R-wave peak of the electrocardiogram (ECG) to the 50% point of the upstroke of the corresponding photoplethysmography waveform; 500 beats of simultaneous systolic arterial pressure and pulse transit time were analysed in each sleep stage for each child. Pulse transit time was normalized to each subject's mean wake pulse transit time. The ability of pulse transit time to predict systolic arterial pressure change was determined by linear mixed-effects modelling. Significant negative correlations between pulse transit time and systolic arterial pressure were found for individual children for each sleep stage [mean correlations for cohort: non-rapid eye movement (NREM) sleep 1 and 2 r = -0.57, slow wave sleep (SWS) r = -0.76, REM r = -0.65, P < 0.01 for all]. Linear mixed-model analysis demonstrated that changes in pulse transit time were a significant predictor of changes in systolic arterial pressure for each sleep stage (P < 0.001). The model of pulse transit time-predicted systolic arterial pressure closely tracked actual systolic arterial pressure changes over time. This study demonstrated that pulse transit time was accurate in tracking systolic arterial pressure changes over time. Thus, the use of pulse transit time as a surrogate measure of changes in systolic arterial pressure in children is a valid, non-invasive and inexpensive method with many potential applications.