Sleep assessments in healthy school-aged children using actigraphy: concordance with polysomnography

Are parent-reported sleep logs essential? A comparison of three approaches to guide open source accelerometry-based nocturnal sleep processing in children

We examined the comparability of children's nocturnal sleep estimates using accelerometry data, processed with and without a sleep log. In a secondary analysis, we evaluated factors associated with disagreement between processing approaches. Children (n = 722, age 5-12 years) wore a wrist-based accelerometer for 14 days during Autumn 2020, Spring 2021, and/or Summer 2021. Outcomes included sleep period, duration, wake after sleep onset (WASO), and timing (onset, midpoint, waketime). Parents completed surveys including children's nightly bed/wake time. Data were processed with parent-reported bed/wake time (sleep log), the Heuristic algorithm looking at Distribution of Change in Z-Angle (HDCZA) algorithm (no log), and an 8 p.m.-8 a.m. window (generic log) using the R-package 'GGIR' (version 2.6-4). Mean/absolute bias and limits of agreement were calculated and visualised with Bland-Altman plots. Associations between child, home, and survey characteristics and disagreement were examined with tobit regression. Just over half of nights demonstrated no difference in sleep period between sleep log and no log approaches. Among all nights, the sleep log approach produced longer sleep periods (9.3 min; absolute mean bias [AMB] = 28.0 min), shorter duration (1.4 min; AMB = 14.0 min), greater WASO (11.0 min; AMB = 15.4 min), and earlier onset (13.4 min; AMB = 17.4 min), midpoint (8.8 min; AMB = 15.3 min), and waketime (3.9 min; AMB = 14.8 min) than no log. Factors associated with discrepancies included smartphone ownership, bedroom screens, nontraditional parent work schedule, and completion on weekend/summer nights (range = 0.4-10.2 min). The generic log resulted in greater AMB among sleep outcomes. Small mean differences were observed between nights with and without a sleep log. Discrepancies existed on weekends, in summer, and for children with smartphones and screens in the bedroom.

Day-to-day bidirectional associations between sleep and emotion states in early childhood: Importance of end-of-day mood for sleep quality

OBJECTIVES

Poor quality sleep can impact emotions and emotion regulation, resulting in a "sleep-mood" cycle where poor sleep affects mood and vice-versa. This relationship is poorly understood during early childhood, when sleep patterns and emotion displays are rapidly changing. This study aimed to understand the day-to-day effects of poor sleep on emotions in preschoolers by using objective (actigraphy) and subjective (ecological momentary assessment) measures to assess both between- and within-child effects. We hypothesized that disrupted sleep would lead to affect disruptions and vice versa.

METHODS

This study included 133 preschoolers and their caregivers recruited from the community. Children's sleep was measured via actigraphy (ActiGraph GT3X+) across 1week. Affect was collected concurrently via caregiver report during an ecological momentary assessment protocol. Caregivers reported on their child's affect four times per day: morning, afternoon, early evening, and before bed.

RESULTS

Multilevel modeling analyses revealed that children with sleep disturbances displayed less positive affect overall, more negative affect in the evenings, and alterations in positive affect lability, and that daytime affect was associated with subsequent nighttime sleep. Within-child associations also showed fluctuations in positive affect correlated with shorter sleep durations and later bedtimes.

CONCLUSIONS

This study identified both between- and within-child associations between sleep and affect in early childhood, revealing a dynamic and reciprocal relationship between the two. These findings highlight the importance of considering both sleep and affect in early childhood interventions, as promoting positive affect may enhance sleep quality and vice versa.

The short and long-term effects of a lifestyle intervention in children with mental illnesses: a randomized controlled trial (Movementss study)

BACKGROUND

A lifestyle including poor diet, physical inactivity, excessive gaming and inadequate sleep hygiene is frequently seen among Dutch children. These lifestyle behaviors can cause long-term health problems later in life. Unhealthy lifestyle and poor physical health are even more prevalent among children with mental illness (MI) such as autism, attention-deficit/hyperactivity disorder, depression, and anxiety. However, research on lifestyle interventions among children with MI is lacking. As a result, there are currently no guidelines, or treatment programs where children with MI and poor lifestyle can receive effective support. To address these issues and to provide insight into the effectiveness of lifestyle interventions in children with MI and their families, the Movementss study was designed. This paper describes the rationale, study design, and methods of an ongoing randomized controlled trial (RCT) comparing the short-term (12 weeks) and long-term (1 year) effects of a lifestyle intervention with care as usual (CAU) in children with MI and an unhealthy lifestyle.

METHODS

A total of 80 children (6-12 years) with MI according to DSM-V and an unhealthy lifestyle are randomized to the lifestyle intervention group or CAU at a specialized child and adolescent mental hospital. The primary outcome measure is quality of life measured with the KIDSCREEN. Secondary outcomes include emotional and behavior symptoms, lifestyle parameters regarding diet, physical activity, sleep, and screen time, cognitive assessment (intelligence and executive functions), physical measurements (e.g., BMI), parenting styles, and family functioning, prior beliefs, adherence, satisfaction, and cost-effectiveness. Assessments will take place at the start of the study (T0), after 12 weeks (T1), six months (T2), and 12 months of baseline (T3) to measure long-term effects.

DISCUSSION

This RCT will likely contribute to the currently lacking knowledge on lifestyle interventions in children with MI.

TRIAL REGISTRATION

trialsearch.who.int/ NL9822. Registered at November 2nd, 2021.

A Latent Profile Analysis of Sleep, Anxiety, and Mood in Youth with Craniopharyngioma

Craniopharyngioma is a histologically benign brain tumor that arises in the suprasellar region affecting critical neurovascular structures including the hypothalamic-pituitary-adrenal axis and optic pathways. Children with craniopharyngioma often experience excessive daytime sleepiness (EDS) which may be compounded by anxiety and depression. The current study investigated disparate sleep profiles to better understand psychological adjustment among children diagnosed with craniopharyngioma.

METHOD

Actigraphs recorded nightly sleep data, including measures of sleep onset latency (SOL) and wake after sleep onset (WASO), in a cohort of 80 youth between the ages of 2 and 20 years (median age = 9). Parent reports of behavioral and emotional functioning were included in the analysis. A latent profile analysis examined disparate sleep profiles, and a multinomial logistic regression examined differences of anxiety and depression among the sleep profiles.

RESULTS

The latent profile analysis revealed three sleep profiles: "healthy sleepers" (68.8%), "night wakers" (21.3%), and "prolonged onset sleepers" (10.0%). Contrary to expectations, sleep profiles were not associated with daytime anxiety (β = 2.26-4.30, p > .05) or depression (β = -5.87-4.74, p > .05).

CONCLUSIONS

Youth with craniopharyngioma demonstrate poor sleep and EDS. Those with delayed SOL and prolonged WASO are particularly vulnerable to disrupted nighttime sleep, which may significantly compound EDS. Disrupted sleep was not associated with anxiety or depression, which may be related to the overall poor sleep and daytime sleepiness or to timing, as patients were early in their treatment course. Further study should evaluate the factors underlying sleepiness and daytime function in patients with craniopharyngioma.

Measuring sleep health in primary school-aged children: A systematic review of instruments and their content validity

Study Objectives

This review aimed to summarize instruments that measure one or more domains of sleep health (i.e. duration, quality, efficiency, timing, daytime sleepiness and sleep-related behaviors) in a general population of 4–12-year old children, and to assess these instruments’ content validity. Other measurement properties were evaluated for instruments with indications of sufficient content validity.

Methods

A systematic literature search was performed in PubMed, PsycINFO, Web of Science, and EmBase. Methodological quality, content validity, and other measurement properties were assessed via the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) methodology. Instruments with indications of sufficient content validity (i.e. relevance, comprehensiveness and comprehensibility) were further evaluated on other measurement properties (i.e. other aspects of validity, reliability, responsiveness). A modified GRADE approach was applied to determine the quality of evidence.

Results

Twenty instruments, containing 36 subscales, were included. None of the instruments measured all sleep health domains. For five (subscales of) instruments sufficient relevance and comprehensibility was found. The quality of evidence ranged from very low to moderate. For these five instruments all additional measurement properties were assessed. Sufficient results were found for structural validity (n = 1), internal consistency (n = 1), and construct validity (n = 1), with quality of evidence ranging from very low to high.

Conclusions

Several (subscales of) instruments measuring domains of child sleep health showed good promise, demonstrating sufficient relevance, comprehensibility, and some also sufficient results on other measurement properties. However, more high quality studies on instrument development and the evaluation of measurement properties are required.

PROSPERO registration number: CRD42021224109

Do Anxiety and Mood Vary among Disparate Sleep Profiles in Youth with Craniopharyngioma? A Latent Profile Analysis

Craniopharyngioma is a histologically benign brain tumor that arises in the suprasellar region affecting critical neurovascular structures including the hypothalamic-pituitary-adrenal axis and optic pathways. Children with craniopharyngioma often experience excessive daytime sleepiness which may be compounded by anxiety and depression. The current study investigated disparate sleep profiles to better understand psychological adjustment among children diagnosed with craniopharyngioma. Method: Actigraphs recorded nightly sleep data, including measures of sleep onset latency and wake after sleep onset, in a cohort of 80 youth between the ages of 2 and 20 years (median age = 9). Parent reports of behavioral and emotional functioning were included in the analysis. A latent profile analysis examined disparate sleep profiles, and a multinomial logistic regression examined differences of anxiety and depression among the sleep profiles. Results: The latent profile analysis revealed three sleep profiles: "variable sleepers" (48.3%), "consistently poor sleepers" (45.4%), and "night wakers" (6.4%). Consistently poor sleepers had lower rates of anxiety (g = .76; p = .009) and depression (g = .81; p = .003) than variable sleepers and had significantly lower rates of anxiety than night wakers (g = .52; p = .05); all other differences were nonsignificant (ps > .05). Discussion: Youth with craniopharyngioma who have nightly variations in sleep may have worse psychological functioning than those with more consistent, albeit poor, sleep patterns. Patients with craniopharyngioma who report variable sleep should be assessed for anxiety and depression to prevent and intervene on emotional difficulties that may be reciprocally related to sleep.

Memory for emotional images across sleep versus wake in school-aged children

Sleep is important for emotional well-being, memory, and development in children. Regarding memory, sleep has been shown to advantage accuracy for declarative tasks but not procedural tasks. There is some evidence to suggest that sleep provides a relatively greater benefit for memory of negative emotional versus neutral images. However, the extent to which sleep benefits emotionally positive memories in children is not clear. This study assessed memory after nocturnal sleep versus daytime wake in a within-person design involving a sample of 40 children aged 7 to 14 years (M = 10.6 ± 1.9 years; 18 boys and 22 girls) for images of negative, neutral, and positive valences. Results show that after accounting for response time, memory accuracy overall was greater after sleep compared with equivalent time of wake and memory accuracy was greatest for positive images compared with both negative and neutral images. However, there was no difference between memory for negative images and that for neutral images in children, and there was no condition by valence interaction. Sleep characteristics as recorded using actigraphy, diary, and parent report were not predictive of memory performance after sleep when correcting for multiple comparisons. Overall, the results suggest that sleep may benefit memory in otherwise healthy children but that despite a bias toward memory for positive items over both negative and neutral items, there is not a relatively greater benefit for emotional versus neutral memory consolidation across sleep periods compared with wake periods.

A Comparison of Self- and Proxy-Reported Subjective Sleep Durations With Objective Actigraphy Measurements in a Survey of Wisconsin Children 6-17 Years of Age

Children's sleep quality and duration are important to overall development, health, and wellbeing. However, measuring children's sleep is challenging, especially in situations where objective assessment is impractical. This study aimed to assess age and proxy effects in comparing subjective sleep duration with objective measures, in a community-based sample of Wisconsin children (aged 6-17 years), recruited from 2014-2017. The sample participants had a mean age of 11.4 (standard deviation, 3.3) years and 52% of them were male. We used linear mixed effects models to test for age effects in proxy- and self-report groups separately, and a quasiexperimental regression discontinuity approach to compare subjective sleep duration with objective actigraphy estimates across proxy- and self-report groups. We found evidence of systematic overestimation of sleep duration when using subjective measurements but did not find evidence of age effects in either group. Based on these analyses, we found evidence of differential overestimation by proxy- or self-report condition. Proxy reporters overestimated sleep duration by 2.3 hours (95% confidence interval: 2.2, 2.4), compared with 1.0 hour (95% confidence interval: 0.7, 1.2) for self-reporters. These findings suggest that proxy- versus self-reporting conditions are an important consideration when designing a study, and that it might be beneficial to reduce the age at which children self-report.

Shared genetic architecture underlying sleep and weight in children

Meta-analyses suggest shorter sleep as a risk factor for obesity in children. The prevailing hypothesis is that shorter sleep causes obesity by impacting homeostatic processes. Sleep duration and adiposity are both heritable, and the association may reflect shared genetic aetiology. We examined the association between a body mass index (BMI) genetic risk score (GRS) and objectively-measured total sleep time (TST) in a cohort of Norwegian children (enrolled at age four in 2007-2008) using cross-sectional data at age six. The analytical sample included 452 six-year old children with complete genotype and phenotype data. The outcome was actigraphic total sleep time (TST) measured at age six years. Genetic risk of obesity was inferred using a 32-single nucleotide polymorphism (SNP) weighted GRS of BMI. Covariates were BMI-Standard deviation scores (SDS) (which takes into account age and sex) and, in a sensitivity analysis socioeconomic status. Analyses consisted of Pearson's correlations and linear regressions. In our sample, 54% of participants were male; mean (SD) TST, age and BMI were 9.6 (0.8) hours, 6.0 (0.2) years and 15.3 (1.2) kg/m², respectively. BMI and TST were not correlated, r = -0.003, p = 0.946. However, the BMI GRS was associated with TST after adjusting for BMI-SDS, standardised β = -0.11; 95% confidence interval (CI) = -0.22, -0.01. To our knowledge, this is the first study to establish a relationship between genetic risk of obesity and objective sleep duration in children. Findings suggest some shared genetic aetiology underlying these traits. Future research could identify the common biological pathways through which common genes predispose to both shorter sleep and increased risk of obesity.

Identifying bedrest using waist-worn triaxial accelerometers in preschool children

Purpose

To adapt and validate a previously developed decision tree for youth to identify bedrest for use in preschool children.

Methods

Parents of healthy preschool (3-6-year-old) children (n = 610; 294 males) were asked to help them to wear an accelerometer for 7 to 10 days and 24 hours/day on their waist. Children with ≥3 nights of valid recordings were randomly allocated to the development (n = 200) and validation (n = 200) groups. Wear periods from accelerometer recordings were identified minute-by-minute as bedrest or wake using visual identification by two independent raters. To automate visual identification, chosen decision tree (DT) parameters (block length, threshold, bedrest-start trigger, and bedrest-end trigger) were optimized in the development group using a Nelder-Mead simplex optimization method, which maximized the accuracy of DT-identified bedrest in 1-min epochs against synchronized visually identified bedrest (n = 4,730,734). DT's performance with optimized parameters was compared with the visual identification, commonly used Sadeh’s sleep detection algorithm, DT for youth (10-18-years-old), and parental survey of sleep duration in the validation group.

Results

On average, children wore an accelerometer for 8.3 days and 20.8 hours/day. Comparing the DT-identified bedrest with visual identification in the validation group yielded sensitivity = 0.941, specificity = 0.974, and accuracy = 0.956. The optimal block length was 36 min, the threshold 230 counts/min, the bedrest-start trigger 305 counts/min, and the bedrest-end trigger 1,129 counts/min. In the validation group, DT identified bedrest with greater accuracy than Sadeh’s algorithm (0.956 and 0.902) and DT for youth (0.956 and 0.861) (both P<0.001). Both DT (564±77 min/day) and Sadeh’s algorithm (604±80 min/day) identified significantly less bedrest/sleep than parental survey (650±81 min/day) (both P<0.001).

Conclusions

The DT-based algorithm initially developed for youth was adapted for preschool children to identify time spent in bedrest with high accuracy. The DT is available as a package for the R open-source software environment (“PhysActBedRest”).

Which healthy lifestyle habits mitigate the risk of obesity and cardiometabolic risk factors in Caucasian children exposed to in utero adverse gestational factors?

BACKGROUND AND AIMS

This study explored if lifestyle habits [physical activity (PA), sleep duration, intake of fruits and vegetables, grains, and dairy products] can moderate the positive associations between prenatal exposure to suboptimal gestational factors (SGF: i.e. gestational diabetes mellitus, hypertensive disorders during pregnancy, maternal smoking during pregnancy) and obesity and cardiometabolic risk factors in children.

METHODS AND RESULTS

Data from the "Quebec Adiposity and Lifestyle Investigation in Youth" (QUALITY) study collected between 2005 - 2008 in Montreal and Quebec City, were used. Analyses included a sample of 619 children aged 8-10 years. Children's PA and sleep duration were obtained using an accelerometer and daily servings of food were assessed using three 24 h diet recalls. Moderation analyses were performed to investigate if each lifestyle habit, in all children, and in boys and girls, could reduce the positive associations between SGF, and obesity and cardiometabolic risk factors. High LPA duration was protective against low levels of HDL cholesterol in boys who were exposed to more than one SGF (p = 0.005). Sleep duration did not have a protective effect respectively against high waist circumference and obesity in children and girls who were prenatally exposed to maternal smoking during pregnancy. Diet and MVPA did not moderate the positive associations between SGF, obesity and cardiometabolic risk factors in children.

CONCLUSION

Among the three lifestyle habits, only LPA had a protective effect against low levels of HDL-cholesterol in boys. More studies are needed to confirm these results to inform future lifestyle intervention in this population.

Sleep assessment by means of a wrist actigraphy-based algorithm: agreement with polysomnography in an ambulatory study on older adults

The purpose of the present work is to examine, on a clinically diverse population of older adults (N = 46) sleeping at home, the performance of two actigraphy-based sleep tracking algorithms (i.e., Actigraphy-based Sleep algorithm, ACT-S1 and Sadeh's algorithm) compared to manually scored electroencephalography-based PSG (PSG-EEG). ACT-S1 allows for a fully automatic identification of sleep period time (SPT) and within the identified sleep period, the sleep-wake classification. SPT detected by ACT-S1 did not differ statistically from using PSG-EEG (bias = -9.98 min; correlation 0.89). In sleep-wake classification on 30-s epochs within the identified sleep period, the new ACT-S1 presented similar or slightly higher accuracy (83-87%), precision (86-89%) and F1 score (90-92%), significantly higher specificity (39-40%), and significantly lower, but still high, sensitivity (96-97%) compared to Sadeh's algorithm, which achieved 99% sensitivity as the only measure better than ACT-S1's. Total sleep times (TST) estimated with ACT-S1 and Sadeh's algorithm were higher, but still highly correlated to PSG-EEG's TST. Sleep quality metrics of sleep period efficiency and wake-after-sleep-onset computed by ACT-S1 were not significantly different from PSG-EEG, while the same sleep quality metrics derived by Sadeh's algorithm differed significantly from PSG-EEG. Agreement between ACT-S1 and PSG-EEG reached was highest when analyzing the subset of subjects with least disrupted sleep (N = 28). These results provide evidence of promising performance of a full-automation of the sleep tracking procedure with ACT-S1 on older adults. Future longitudinal validations across specific medical conditions are needed. The algorithm's performance may further improve with integrating multi-sensor information.

Which objective sleep elements predict children's perceptions of good sleep quality? A preliminary investigation based on polysomnography and actigraphy

OBJECTIVES

Objective sleep elements that underlie child ratings of sleep quality are largely unknown. Child-based sleep recommendations, therefore, typically focus on duration. An expert panel recently provided specific recommendations regarding objective sleep parameters that correspond with higher quality sleep, but child-based studies from which to draw conclusions were notably limited. The present study used actigraphy and polysomnography to explore sleep continuity and architectural variables that correspond with higher ratings of sleep quality in a sample of school-aged children.

METHODS

Fifty-two healthy, prepubertal children (aged 7-11 years) completed one night of unattended ambulatory polysomnography at home with concurrent actigraphy and provided sleep quality ratings the following morning. Associations between sleep variables and subjective ratings were examined using polynomial regression models to examine potential linear and nonlinear relationships.

RESULTS

In contrast to findings among adults, total sleep time, sleep onset latency, and sleep efficiency values were unrelated to child ratings of sleep quality. Wake after sleep onset (WASO) showed a curvilinear (reversed j-shaped) relationship such that perceptions of sleep quality were high when WASO values were less than approximately 30 minutes. For sleep architecture, N1% showed a significant quadratic association with sleep quality such that N1% between 2% and 6% corresponded with high sleep quality ratings.

CONCLUSIONS

Our findings support expert recommendations regarding WASO values that predict high quality sleep in children, but also await replication. There is need for additional research aimed at understanding objective sleep elements and other influences of children's perceptions of sleep quality using linear and nonlinear models.

Actigraphy versus Polysomnography to Measure Sleep in Youth Treated for Craniopharyngioma

OBJECTIVE/BACKGROUND

Youth with craniopharyngioma are at increased risk for excessive daytime sleepiness and narcolepsy. Polysomnography (PSG) is the gold standard for diagnosing sleep disorders, but is time-intensive, costly, and does not offer an in vivo measure of typical sleep routine. We determined the sensitivity, specificity, and accuracy of actigraphy compared with PSG in measuring nocturnal sleep in pediatric craniopharyngioma.

PARTICIPANTS

Fifty youth with craniopharyngioma (age 3-20 years) were assessed by overnight PSG and concurrent actigraphy after surgical resection and before proton therapy.

METHODS

PSG and actigraphy data were synchronized utilizing an epoch-by-epoch comparison method. Sensitivity, specificity, and accuracy were calculated using measures of true wake, true sleep, false wake, and false sleep. Bland-Altman plots were conducted to further assess level of agreement.

RESULTS

Actigraphy was 93% sensitive (true sleep [TS]) and 87% accurate (ability to detect TS and true wake) in measuring sleep versus wakefulness and was a reliable measure of sleep efficiency (SE) and sleep latency (SL). Specificity (true wake) was poor (55%) and total sleep time (TST) was underestimated by an average of 15.1 min. Wake after sleep onset (WASO) was overestimated by an average of 14.7 min.

CONCLUSIONS

Actigraphy was highly sensitive and accurate and was a reliable measure of SE and SL. Although there were differences in TST and WASO measurements by actigraphy and PSG, our findings provide the basis for future studies on the use of actigraphy to monitor treatment response to wakefulness-promoting medications in youth with craniopharyngioma who demonstrate excessive daytime sleepiness.

Sleep patterns and sleep deprivation recorded by actigraphy in 4th-grade and 5th-grade students

OBJECTIVE

This study investigates sleep patterns of fourth- and fifth-grade students using actigraphy.

METHODS

The study included 257 students enrolled in a Southwestern US school district who participated in a novel sleep science curriculum during the Spring 2016-17 and Fall 2017-18 semesters and met the study inclusion criteria. As part of this curriculum, participants underwent 5-7 days of continuous wrist actigraphy and completed an online sleep diary.

RESULTS

Approximately two-thirds of the 9-11-year-old fourth- and fifth-grade students slept less than the minimum 9 h per night recommended by both the American Academy of Sleep Medicine/Sleep Research Society and the National Sleep Foundation. The sleep midpoint time on weekends was about 1 h later than on weekdays. There was a significant effect of age on sleep duration. Compared to 9-year old students, a larger proportion of 10-year old students had a sleep duration less than 8.5 h. Boys had shorter sleep duration than girls, and a larger percentage of boys obtained less than 9 h of sleep compared to girls.

CONCLUSIONS

Insufficient sleep is a highly prevalent condition among 9-11-year-old fourth- and fifth-grade elementary students. Importantly, there is a difference between sleep patterns on weekdays and weekends which may portend greater problems with sleep in adolescence and young adulthood.

Short- and Long-Term Effects of CBT-I in Groups for School-Age Children Suffering From Chronic Insomnia: The KiSS-Program

OBJECTIVE/BACKGROUND

This intervention study evaluates the short- and long-term effects of cognitive behavior therapy for insomnia (CBT-I) in groups for school-age children and their parents, named the KiSS-program. CBT-I was implemented in three sessions for children and three sessions for parents.

PARTICIPANTS AND METHODS

All in all, 112 children with chronic childhood insomnia were randomly assigned to a wait-list (WL) control or treatment condition.

RESULTS

According to subjective measures as well as objective wrist actigraphy, children in the CBT-I condition reported greater improvements in sleep behavior immediately after the treatment compared to the WL group. Improvements in sleep behavior after CBT-I persisted over the 3-, 6-, and 12-month follow-up assessments.

CONCLUSIONS

The present study is the first randomized controlled trial that provides evidence for the long-term effectiveness of CBT-I in treating school-age children with chronic insomnia.

Identifying bedrest using 24-h waist or wrist accelerometry in adults

Objectives

To adapt and refine a previously-developed youth-specific algorithm to identify bedrest for use in adults. The algorithm is based on using an automated decision tree (DT) analysis of accelerometry data.

Design

Healthy adults (n = 141, 85 females, 19–69 years-old) wore accelerometers on the waist, with a subset also wearing accelerometers on the dominant wrist (n = 45). Participants spent ≈24-h in a whole-room indirect calorimeter equipped with a force-platform floor to detect movement.

Methods

Minute-by-minute data from recordings of waist-worn or wrist-worn accelerometers were used to identify bedrest and wake periods. Participants were randomly allocated to development (n = 69 and 23) and validation (n = 72 and 22) groups for waist-worn and wrist-worn accelerometers, respectively. The optimized DT algorithm parameters were block length, threshold, bedrest-start trigger, and bedrest-end trigger. Differences between DT classification and synchronized objective classification by the room calorimeter to bedrest or wake were assessed for sensitivity, specificity, and accuracy using a Receiver Operating Characteristic (ROC) procedure applied to 1-min epochs (n = 92,543 waist; n = 30,653 wrist).

Results

The optimal algorithm parameter values for block length were 60 and 45 min, thresholds 12.5 and 400 counts/min, bedrest-start trigger 120 and 400 counts/min, and bedrest-end trigger 1,200 and 1,500 counts/min, for the waist and wrist-worn accelerometers, respectively. Bedrest was identified correctly in the validation group with sensitivities of 0.819 and 0.912, specificities of 0.966 and 0.923, and accuracies of 0.755 and 0.859 by the waist and wrist-worn accelerometer, respectively. The DT algorithm identified bedrest/sleep with greater accuracy than a commonly used automated algorithm (Cole-Kripke) for wrist-worn accelerometers (p<0.001).

Conclusions

The adapted DT accurately identifies bedrest in data from accelerometers worn by adults on either the wrist or waist. The automated bedrest/sleep detection DT algorithm for both youth and adults is openly accessible as a package “PhysActBedRest” for the R-computer language.

Sleep and quality of life of patients with glycogen storage disease on standard and modified uncooked cornstarch

BACKGROUND

Glycemic control in hepatic glycogen storage diseases (GSDs) relies on specific nutritional recommendations, including strict avoidance of a fasting period. Uncooked cornstarch (UCCS) is an important therapeutic component. A new modified UCCS, Glycosade™, was created with the objective of prolonging euglycemia. We aimed to determine the length of euglycemia on Glycosade™ using a continuous glucose monitor (CGM) and to evaluate whether longer euglycemia and thus less nighttime interruptions would improve sleep and quality of life (QoL) after the introduction of the modified cornstarch.

METHODS

We conducted a prospective cohort study to assess quality and quantity of sleep and quality of life (QoL) in patients with GSDs on standard UCCS and after the introduction of Glycosade™. Sleep and QoL evaluation was done for patients using validated questionnaires, a standardized sleep diary and actigraphy. Length of fast and glucose variability were determined with CGM.

RESULTS

Nine adults with GSD Ia took part in the study. Glycosade™ introduction was done under close supervision during a hospital admission. Comparison of sleep in 9 patients showed sleep disturbances on standard UCCS that were improved with Glycosade™. QoL was normal both pre and post Glycosade™. The CGM confirmed maintenance of a longer fasting period with Glycosade™ at home.

CONCLUSION

Glycosade™ represents an alternative option for GSD patients. We showed possible benefits in terms of sleep quality. We also confirmed the longer length of fast on Glycosade™.

SYNOPSIS

A new modified form of uncooked starch for patients with glycogen storage disease represents an alternative option as it showed a longer length of fast and improvements in sleep quality.

Sleep and cognitive functioning in childhood: Ethnicity, socioeconomic status, and sex as moderators

We examined children's sleep at age 9 as a predictor of developmental trajectories of cognitive performance from ages 9 to 11 years. The effects of sleep on cognition are not uniform and thus we tested race/ethnicity, socioeconomic status (SES), and sex as moderators of these associations. At the first assessment, 282 children aged 9.44 years (52% boys, 65% European American [EA], 35% African American [AA]) participated. Two more waves of data collection spaced 1 year apart followed. The majority of children (63%) were living at or below the poverty line. Children's sleep was measured objectively with actigraphy and 2 well-established sleep parameters were derived: duration, indexed by sleep minutes between sleep onset and wake time, and quality, indexed by efficiency. Multiple cognitive functioning domains were examined with the Woodcock Johnson Tests of Cognitive Abilities (WJ III). Across the sample, higher sleep efficiency, but not duration, was associated with better cognitive performance. Significant moderation effects emerged. Controlling for SES, AA children scored lower on general intellectual ability and working memory (WM) at age 11 only if they experienced lower sleep efficiency at age 9. Further, boys scored lower on general abilities and processing speed (PS) at age 11 only if their sleep efficiency was lower at age 9. Findings indicate that lower sleep efficiency may contribute to lower cognitive functioning especially for AA children and boys. These vulnerabilities appear to emerge early in development and are maintained over time. Results underscore the importance of individual differences in explicating relations between sleep and children's cognitive performance. (PsycINFO Database Record

Reliability and validity of the Spanish version of the Children's Sleep Habits Questionnaire (CSHQ-SP) in school-age children

BACKGROUND

Sleep disorders in schoolchildren are a common problem worldwide, and when are not adequately diagnosed and treated, their negative impact on daytime functioning may be significant. The aim of this study was to evaluate the psychometric properties of the Spanish version of the Children's Sleep Habits Questionnaire (CSHQ).

METHODS

Participants were 286 school-aged children from a community-based sample, aged 4 to 7 years. The sleep behaviour was evaluated using the CSHQ and actigraphy (ActiSleep monitor). The CSHQ was adapted to the Spanish language. The internal consistency of the questionnaire and the test-retest reliability between scores at baseline and three-weeks-later were estimated. Associations between CSHQ items and accelerometer sleep quality indicators were used as indicators of concurrent validity.

RESULTS

Cronbach's alpha coefficients for the subscales ranged from 0.60 to 0.81, and 0.81 for the full scale; the intraclass correlation coefficients ranged from 0.56 to 0.81. A moderate correlation was observed in sleep latency and awakenings measurements using both parents' reported sleep habits (CSHQ-SP) and sleep quality indicators (ActiSleep).

CONCLUSIONS

The CSHQ-SP has demonstrated adequate psychometric properties, and it serves as a useful instrument for clinical and research setting.

The Pediatric Sleep Clinical Global Impressions Scale-A New Tool to Measure Pediatric Insomnia in Autism Spectrum Disorders

OBJECTIVE

To pilot a clinician-based outcome measure that provides complementary information to objective measures and parent-based questionnaires for insomnia in children with autism spectrum disorders (ASD).

METHOD

The authors developed a Pediatric Sleep Clinical Global Impressions Scale (CGI). Questions included (1) the child's ability to fall asleep and remain sleeping independently (i.e., apart from parents); (2) bedtime resistance; (3) sleep onset delay; (4) night awakening; (5) parental satisfaction with their child's current sleep patterns; (6) family functioning as affected by their child's current sleep patterns; and (7) clinician's overall concern with the child's sleep. After refining the instrument through the evaluation of vignettes by ASD and sleep experts, the authors piloted the Pediatric Sleep CGI in a 12-week randomized trial of iron supplementation in children with ASD. Clinicians completed Pediatric Sleep CGIs and structured sleep histories, parents completed the Children's Sleep Habits Questionnaire (CSHQ), and children wore actigraphy watches.

RESULTS

In repeated measures models, the Pediatric Sleep CGI and CSHQ were correlated for sleep onset delay (r = .66, p < .001), night wakings (r = .40, p < .001), and total score (r = .29, p < .001). The CGI-S sleep onset delay and actigraphy sleep onset delay scores (r = .75, p = .0095) were also correlated. The overall CGI-S showed improvement with therapy (p = .047).

CONCLUSION

The Pediatric Sleep CGI shows promise in measuring clinician-rated outcomes in pediatric insomnia in children with ASD. Larger samples will be necessary to examine reliability, validity, and measure to change, as well as applicability to other populations with pediatric insomnia.

Children's Sleep and Academic Achievement: The Moderating Role of Effortful Control

Poor sleep is thought to interfere with children's learning and academic achievement (AA). However, existing research and theory indicate there are factors that may mitigate the academic risk associated with poor sleep. The purpose of this study was to examine the moderating role of children's effortful control (EC) on the relation between sleep and AA in young children. One hundred and three 4.5- to 7-year-olds (M = 5.98 years, SD = 0.61) wore a wrist-based actigraph for five continuous weekday nights. Teachers and coders reported on children's EC. EC was also assessed with a computer-based task at school. Additionally, we obtained a standardized measure of children's AA. There was a positive main effect of sleep efficiency to AA. Several relations between sleep and AA were moderated by EC and examination of the simple slopes indicated that the negative relation between sleep and AA was only significant at low levels of EC.

Effect of the IDEFICS multilevel obesity prevention on children's sleep duration

BACKGROUND

According to recent findings, short sleep duration is associated with overweight in children. However, primary prevention efforts aimed at achieving adequate sleep among children are scarce. Therefore, the 'Identification and prevention of Dietary-induced and lifestyle-induced health EFfects In Children and infantS' (IDEFICS) study implemented a multilevel intervention that included sleep duration as a key behavioural target. The aim of this study is to evaluate sleep duration among children participating in the IDEFICS study.

METHODS

The IDEFICS nocturnal sleep intervention was included as part of stress reduction educational messages aimed at parents and children. Sleep was assessed by a parental 24-h recall (only weekdays; n = 8,543) and by a diary (weekdays and weekends separately; n = 4,150). Mixed linear models tested the intervention effect on sleep duration change between baseline when children were 2-9.9 years of age (2007/2008) and follow-up (2009/2010). Logistic mix models were used to study the intervention effect on the presence of TV in the children's bedroom (one of the intervention messages; n = 8,668). Additionally, parents provided qualitative data regarding exposure to the intervention.

RESULTS

About 51.1% of the parents in the intervention regions reported awareness of the sleep intervention. A small intervention effect was seen on weeknight sleep duration in that the decrease in sleep duration over 2 years was smaller in the intervention (15 min) as compared with control regions (19 min) (p = 0.044). There was no overall intervention effect on weekend sleep duration or on the presence of a TV in the bedroom. A small significant time effect between baseline and follow-up was found on bedroom TV presence depending on self-reported intervention exposure (3% increase in TV presence in exposed versus 6.6% increase in non-exposed). Children without a TV in the bedroom had longer nocturnal sleep duration.

DISCUSSION

The sleep component of the intervention did not lead to clinically relevant changes in sleep duration. Future interventions aimed at young children's sleep duration could benefit from more specific and intense messaging than that found in the IDEFICS intervention. Future research should use objective measures of sleep duration as well as intermediate outcomes (sleep knowledge, sleep environment and sleep practices).

Daily dynamics in sleep and behavior of young African-American children: A convoluted dyad?!

Prior research has provided evidence that in children sleep and behavior are related. We aimed to determine the association between naturalistic daily variations in sleep and behavioral functioning. African American children, 5.4±1.7years old, living on the south side of Chicago participated in a repeated measures study to assess this sleep-behavior link. Data was obtained from three separate two-week periods of 24-hour actigraphy and the parental version of the Behavioral Assessment System for Children. Canonical correlations analyses were applied to investigate the relation between individual changes in sleep and behavior. After 1-month, weekday average sleep duration primarily related to internalizing behaviors, while within-child variability of sleep related to behavioral changes which may involve internalizing and externalizing symptoms. Week-weekend differences in sleep associated with maladaptive social skills. Over a 6-week period, sleep onset latency and sleep offset latency related to behavioral symptoms and maladaptive skills. Over a period of 3-months, sleep associated with symptomatic behaviors while the adverse impact of within-child variability of sleep attenuated. Alternatively, the week-weekend differences in bedtime, wake-up time, wake after sleep onset and sleep onset latency in particular related to internalizing and externalizing behavior problems. Findings showed that poor sleep related to dysfunctional behaviors. While maladaptive at the beginning, they may develop into symptomatic behaviors with potentially internalizing characteristics. As time goes on, individual changes in sleep onset and offset might be important clinical markers of a chronic 'social dysregulation'. Continued sufficient and regular sleep may improve daytime and nighttime behavioral regulation in early childhood.

The Effects of Lithium Carbonate Supplemented with Nitrazepam on Sleep Disturbance during Cannabis Abstinence

STUDY OBJECTIVE

Sleep disturbance is a hallmark feature of cannabis withdrawal. In this study we explored the effects of lithium treatment supplemented with nitrazepam on objective and subjective measures of sleep quality during inpatient cannabis withdrawal.

METHODS

Treatment-seeking cannabis-dependent adults (n = 38) were admitted for 8 days to an inpatient withdrawal unit and randomized to either oral lithium (500 mg) or placebo, twice daily in a double-blind RCT. Restricted nitrazepam (10 mg) was available on demand (in response to poor sleep) on any 3 of the 7 nights. Dependent outcome measures for analysis included repeated daily objective actigraphy and subjective sleep measures throughout the 8 day detox, subjective cannabis withdrawal ratings, and detoxification completion rates.

RESULTS

Based on actigraphy, lithium resulted in less fragmented sleep compared to placebo (p = 0.04), but no other objective measures were improved by lithium. Of the subjective measures, only nightmares were suppressed by lithium (p = 0.04). Lithium did not have a significant impact on the use of nitrazepam. Sleep bout length (p < 0.0001), sleep efficiency (p < 0.0001), and sleep fragmentation (p = 0.05) were improved on nights in which nitrazepam was used. In contrast, only night sweats improved with nitrazepam from the subjective measures (p = 0.04). A Cox regression with daily repeated measures of sleep efficiency averaged across all people in the study a predictor suggests that a one-unit increase in sleep efficiency (the ratio of total sleep time to the total time in bed expressed as a percentage) resulted in a 14.6% increase in retention in treatment (p = 0.008, Exp(B) = 0.854, 95% CI = 0.759-0.960). None of the other sleep measures, nor use of lithium or nitrazepam were significantly associated with retention in treatment.

CONCLUSIONS

Lithium seems to have only limited efficacy on sleep disturbance in cannabis withdrawal. However the nitrazepam improved several actigraphy measures of sleep disturbance, warranting further investigation. Discord between objective and subjective sleep indices suggest caution in evaluating treatment interventions with self-report sleep data only.

Anxiety disorders and comorbid sleep problems in school-aged youth: review and future research directions

This review examines the relationship between anxiety disorders and sleep related problems (SRPs) in school-aged youth. Following an overview of normative sleep patterns and maturational sleep changes, the review addresses issues related to sleep measurement. SRPs are reviewed in relation to executive functions (e.g. affect regulation) as is the shared role of neurological regions in the regulation of anxiety and sleep. Studies of the association between SRPs and anxiety in anxiety-disordered samples are reviewed with explicit consideration of the potential mechanisms underlying the sleep-anxiety relationship (e.g., arousal, sleep hygiene, parental accommodation). Specific cognitive-behavioral treatments for SRPs and anxiety are reviewed with regard to their impact on comorbid anxiety or SRPs. Methodological limitations are noted and recommendations for future research are proposed.

To sleep or not to sleep: a repeated daily challenge for African American children

AIMS

Sleep is important for children, because of the impact on their development and well-being. Previous survey research suggested that poor sleep occurs more frequently in minorities. However, objective data characterizing their sleep patterns are lacking.

METHODS

Children enrolled in a 1-year cross-sectional sequence designed study centered on a 14-day objective sleep recording, which was repeated three times. Children lived on the South Side of Chicago and were self-defined as being African Americans.

RESULTS

Findings reflect data of 24 children with a mean age of 5.4 ± 1.7 years of which 54.2% were girls. They slept at night 6.51 h and during the day changeably 1.42 h, likely being noon naps during the week and afternoon naps on Saturday and Sunday. Variability in quality of sleep, and also nighttime sleep duration, especially on Friday and Saturday, was characteristic. The highest variability was noted in sleep onset and offset latency, and in the quality of napping. The interrelation of daytime and nighttime sleep changes was suggestive of "catch-up" daytime sleep.

CONCLUSION

At nighttime children habitually obtained few hours of sleep with diurnal sleep fluctuations likely being "a need" and "a chance." Interventions might emphasize on creating optimal opportunities to sleep.

Associations of sleep disturbance with ADHD: implications for treatment

Attention-deficit/hyperactivity disorder (ADHD) is commonly associated with disordered or disturbed sleep. The relationships of ADHD with sleep problems, psychiatric comorbidities and medications are complex and multidirectional. Evidence from published studies comparing sleep in individuals with ADHD with typically developing controls is most concordant for associations of ADHD with: hypopnea/apnea and peripheral limb movements in sleep or nocturnal motricity in polysomnographic studies; increased sleep onset latency and shorter sleep time in actigraphic studies; and bedtime resistance, difficulty with morning awakenings, sleep onset difficulties, sleep-disordered breathing, night awakenings and daytime sleepiness in subjective studies. ADHD is also frequently coincident with sleep disorders (obstructive sleep apnea, peripheral limb movement disorder, restless legs syndrome and circadian-rhythm sleep disorders). Psychostimulant medications are associated with disrupted or disturbed sleep, but also ‘paradoxically’ calm some patients with ADHD for sleep by alleviating their symptoms. Long-acting formulations may have insufficient duration of action, leading to symptom rebound at bedtime. Current guidelines recommend assessment of sleep disturbance during evaluation of ADHD, and before initiation of pharmacotherapy, with healthy sleep practices the first-line option for addressing sleep problems. This review aims to provide a comprehensive overview of the relationships between ADHD and sleep, and presents a conceptual model of the modes of interaction: ADHD may cause sleep problems as an intrinsic feature of the disorder; sleep problems may cause or mimic ADHD; ADHD and sleep problems may interact, with reciprocal causation and possible involvement of comorbidity; and ADHD and sleep problems may share a common underlying neurological etiology.

Do more active children sleep more? A repeated cross-sectional analysis using accelerometry

Aim

To determine whether levels of daytime physical activity are associated with sleep duration and night waking in children assessed using accelerometry, and if these associations change over time.

Methods

24-hour accelerometry data were obtained from 234 children at 3, 5 and 7 years of age for at least 5 days at each time. Sleep duration was estimated using the Sadeh algorithm. Time spent in sedentary, light and moderate-vigorous (MVPA) activity was established using published cut-points. Appropriate statistical techniques were utilised to account for the closed nature of the data (24-hour periods).

Results

Time spent asleep was related more to sedentary or light activity and not to MVPA. The most active (95^th percentile) children spent 55–84 fewer minutes asleep and 16–19 more minutes awake at night compared to the least active (5^th percentile) children. Children with later bedtimes slept less at night (30–40 minutes) and undertook more sedentary (10–15 minutes) but also more light (18–23 minutes) activity during the day. However, no differences in MVPA were apparent according to bedtime. Children slept slightly less on weekend nights (11 minutes) compared with week-nights, but only at 3 years of age. Most relationships were broadly similar at 3, 5 and 7 years of age.

Conclusion

Children who are more physically active during the day have shorter total sleep time and are more awake at night than less active children. The protective effect of sleep on obesity does not appear to be mediated by increased physical activity.

Sleep duration and abnormal serum lipids: the China Health and Nutrition Survey

OBJECTIVE

To examine the associations between sleep duration and total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), apolipoprotein B (ApoB), apolipoprotein A1 (ApoA1), and lipoprotein (a) [Lp(a)].

METHODS

The present study analyzed 8574 adults from the China Health and Nutrition Survey (2009). Sleep duration was classified into < or = 6, 7, 8, 9, and > or = 10 h. Age, education, occupation, current smoking, current drinking, physical activity, body mass index, hypertension, and diabetes were adjusted as confounders in gender-stratified multiple logistic regression models.

RESULTS

Compared with women reporting 8h sleep duration, the odds ratios (ORs) and 95% confidence intervals (CIs) of high TC for those with < or = 6, 7, 9, and > or = 10 h were 1.65 (1.32-2.06), 1.19 (1.00-1.43), 1.11 (0.89-1.39), and 1.27 (1.02-1.60) after adjusting for confounders. Likewise, the ORs (95% CIs) of high LDL-C were 1.71 (1.28-2.29), 1.36 (1.05-1.76), 1.04 (0.74-1.46), and 1.09 (0.78-1.53), whereas those of high ApoB were 1.80 (1.34-2.42), 1.15 (0.88-1.52), 0.95 (0.66-1.35), and 1.00 (0.70-1.43) for women with < or = 6, 7, 9, and > or = 10 h sleep duration, respectively. These associations were not statistically significant in men.

CONCLUSIONS

Both shorter and longer sleep durations were associated with higher risks of abnormal serum lipid profiles in women but not in men.

Actigraphic assessment of sleep disturbances following traumatic brain injury

The current study examined the use of actigraphy in measurement of sleep following traumatic brain injury (TBI). Twenty-one patients with TBI and self-reported sleep and/or fatigue problems and 21 non-injured controls were studied over seven days using actigraphy and sleep diary reports. Although strong associations between diary and actigraphic assessment of sleep duration were observed in both participant groups, agreement between these methods appeared to weaken in patients with TBI. Associations between sleep diary and actigraphic assessments of sleep disturbance, i.e., wake after sleep onset (WASO) and sleep onset latency (SOL) were not apparent in either group, although weaker agreement between methods for WASO was again observed in patients with TBI. Actigraphy may prove useful to supplement self-report measures of sleep following TBI. More work is required to understand the accuracy of these measures in this population.

Continuity and change in poor sleep from childhood to early adolescence

STUDY OBJECTIVES

We examined associations between pubertal maturation and sleep in early adolescence, at age 12 y, and continuity and change in actigraphy-based sleep and parent-reported sleep disorders from age 8 to 12 y. We also explored longitudinal associations between actigraph estimates of sleep and sleep disorders.

DESIGN

A cohort study of children born in 1998 and tested at ages 8 y (standard deviation [SD] = 0.3) and 12 y (SD = 0.5).

PARTICIPANTS

A total of 348 children participated in cross-sectional analyses. We had longitudinal actigraphy data for 188 children and repeated parent reports of sleep disorders for 229 children.

MEASUREMENTS AND RESULTS

At age 8 y, participants wore actigraphs for 7.1 nights (SD = 1.2, range 3-14) on average and at age 12 y for 8.4 nights (SD = 1.7, range 3-11). Sleep disorders were parent-rated based on the Sleep Disturbance Scale for Children. Pubertal maturity was self-reported at age 12 y using the continuous Pubertal Development Scale and the picture-assisted categorical Tanner scales.

RESULTS

Significant mean-level changes toward shorter but higher quality sleep occurred over time. Sleep variables had low to high rank-order stability over time. Sleep disorders were highly stable from age 8 to 12 y. Actigraphy-based sleep and parent-rated sleep disorders showed no association either in cross-section or longitudinally. Pubertal maturation was not associated with worse sleep.

CONCLUSIONS

Sleep in early adolescence can be anticipated from childhood sleep patterns and disorders, but is not associated with pubertal maturity. Although sleep duration becomes shorter, sleep quality may improve during early adolescence. Parent-rated sleep disorders are distinct from actigraph estimates of sleep.

Investigating the Convergence between Actigraphy, Maternal Sleep Diaries, and the Child Behavior Checklist as Measures of Sleep in Toddlers

The current study examined associations among actigraphy, maternal sleep diaries, and the parent-completed child behavior checklist (CBCL) sleep items. These items are often used as a sleep measure despite their unclear validity with young children. Eighty middle class families (39 girls) drawn from a community sample participated. Children (M = 25.34 months, SD = 1.04) wore an actigraph monitor (Mini-Mitter(®) Actiwatch Actigraph, Respironics) for a 72-h period, and mothers completed a sleep diary during the same period. Eighty-nine percent of the mothers and 75% of the fathers also filled out the CBCL (1.5-5). Mother and father CBCL scores were highly correlated. Overall, good correspondence was found between the CBCL filled out by mothers and sleep efficiency and duration derived from maternal sleep diaries (r between -0.39 and -0.25, p ≤ 0.05). Good correspondence was also found between the CBCL filled out by fathers and sleep efficiency as derived from maternal sleep diaries (r between -0.39 and -0.24, p ≤ 0.05), but not with sleep duration (all results were non-significant). Very few correlations between actigraphy and the CLBL scores reached statistical significance. The Bland and Altman method revealed that sleep diaries and actigraphy showed poor agreement with one another when assessing sleep duration and sleep efficiency. However, diary- and actigraphy-derived sleep durations were significantly correlated. Consistent with findings among older groups of children, this study suggests that the CBCL sleep items, sleep diaries, and actigraphy tap into quite different aspects of sleep among toddlers. The choice of which measures to use should be based on the exact aspects of sleep that one aims to assess. Overall, despite its frequent use, the composite sleep score of the CBCL shows poor links to objective measures of sleep duration and sleep efficiency.

Genetic and environmental contributions to sleep-wake behavior in 12-year-old twins

STUDY OBJECTIVES

To examine the role of genetic and environmental factors on sleep behavior in 12-year-old twins matched for family environment.

DESIGN

Population-based twin cohort.

SETTING

Participants were assessed in their home environment.

PATIENTS OR PARTICIPANTS

One hundred thirty-two adolescent twins comprising 25 monozygotic (MZ) and 41 dizygotic (DZ) twin pairs; aged 12.2 ± 0.1 y (mean ± standard deviation).

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

For 2 weeks in their home environment, participants wore a wrist activity monitor and completed a daily sleep diary. Sleep diaries included reports of bedtime, wake time, and estimated sleep onset time. Mean timing, duration, and quality of sleep during the 2 weeks were calculated for each individual and compared within twin pairs. MZ twin correlations were higher than the DZ correlations for total sleep time (MZr = 0.64; DZr = 0.38) and sleep onset latency (MZr = 0.83; DZr = 0.53) and significantly higher for wake after sleep onset (MZr = 0.66; DZr = 0.04) and sleep efficiency (MZr = 0.82; DZr = 0.10). Univariate modeling showed additive genetic factors accounted for 65% of the variance in total sleep time, 83% in sleep onset latency, and 52% and 57% of the variance in wake after sleep onset and sleep efficiency, respectively. A predominant influence of shared environment was found on the timing of sleep (67% for sleep start time, 86% for sleep end time).

CONCLUSIONS

There is a strong genetic influence on the sleep-wake patterns of 12-year-old adolescents. Genes have a greater influence on sleep initiation and sleep maintenance and a smaller role in sleep timing, likely to be influenced by family environment.

Validating actigraphy as a measure of sleep for preschool children

STUDY OBJECTIVES

The algorithms used to derive sleep variables from actigraphy were developed with adults. Because children change position during sleep more often than adults, algorithms may detect wakefulness when the child is actually sleeping (false negative). This study compares the validity of three algorithms for detecting sleep with actigraphy by comparing them to PSG in preschoolers. The putative influence of device location (wrist or ankle) is also examined.

METHODS

Twelve children aged 2 to 5 years simultaneously wore an actigraph on an ankle and a wrist (Actiwatch-L, Mini-Mitter/Respironics) during a night of PSG recording at home. Three algorithms were tested: one recommended for adults and two designed to decrease false negative detection of sleep in children.

RESULTS

Actigraphy generally showed good sensitivity (> 95%; PSG sleep detection) but low specificity (± 50%; PSG wake detection). Intraclass correlations between PSG and actigraphy variables were strong (> 0.80) for sleep latency, sleep duration, and sleep efficiency, but weak for number of awakenings (< 0.40). The two algorithms designed for children enhanced the validity of actigraphy in preschoolers and increased the proportion of actigraphy-scored wake epochs scored that were also PSG-identified as wake. Sleep variables derived from the ankle and wrist were not statistically different.

CONCLUSION

Despite the weak detection of wakefulness, Acti-watch-L appears to be a useful instrument for assessing sleep in preschoolers when used with an adapted algorithm.

Biological rhythm disturbance in remitted bipolar patients

Background

Biological rhythm disturbance is common in bipolar patients and seems to affect the course and prognosis of the illness negatively. The main aim of the current study was to assess biological rhythms in remitted bipolar patients. We also assessed whether there was an association between clinical variables or functioning and biological rhythms in remitted bipolar participants.

Methods

The Biological Rhythms Interview of Assessment in Neuropsychiatry (BRIAN) was used to assess biological rhythm disturbance. It is an 18-item interviewer-administered instrument which allows us to investigate the main areas related to circadian rhythm disturbance (sleep/social, activities, and eating pattern) in bipolar disorder.

Results and discussion

Bipolar patients (n = 107) experienced greater biological rhythm alterations than the control group (n = 100) (BRIAN total scores 35.36 ± 7.11 vs. 32.48 ± 6.10, t = 6.912, p = 0.002, Cohen's d = 0.43, r = 0.21). In particular, patients were more impaired than the control group with regard to sleep/social (14.67 ± 4.14 vs. 13.49 ± 2.91, t = 10.61, p = 0.018, Cohen's d = 0.33, r = 0.16) and activity (8.49 ± 2.51 vs. 7.07 ± 2.13, t = 3.90, p = 0.001, Cohen's d = 0.61, r = 0.29) domains. Furthermore, a significant correlation was found between biological rhythms with residual depressive symptoms (r = 0.459, p < 0.001) and functioning (r = 0.432, p < 0.001). These findings suggest a potential link between biological rhythms and the pathophysiology of bipolar disorder. It highlights the importance of novel instruments (e.g., BRIAN) which allow us to assess biological rhythm disturbance in psychiatry. Finally, specific psychosocial interventions focused on lifestyle regularity may be considered as a supplemental treatment of bipolar illness episodes.

Electronic supplementary material

The online version of this article (doi:10.1186/2194-7511-1-6) contains supplementary material, which is available to authorized users.

Agreement in regard to total sleep time during a nap obtained via a sleep polygraph and accelerometer: a comparison of different sensitivity thresholds of the accelerometer

BACKGROUND

Appropriate sensitivity threshold of accelerometer to measure total sleep time during nap is not established.

PURPOSE

Actigraphy-derived total sleep times during naps were calculated using three different sensitivity threshold values and compared with polysomnography.

METHOD

The mean age of the 60 subjects (53 men and 7 women) was 22.8, ranging from 22 to 27 years. Determination of the sleep stage by the polygraph and the sleep/wake judgment by the accelerometer obeyed the sleep/wake judgment, and the accelerometer was monitored under different sensitivity threshold settings. The study was carried out during one afternoon with a 3-h nap opportunity. Kappa statistics, correlations, and several indices of accuracy were compared using statistical methods.

RESULTS

The mean total sleep times during a nap set for 180 min were 160.4, 151.8, and 140.5 min, respectively, as judged under the low-sensitive, middle-sensitive, high-sensitive settings of an accelerometer worn on the non-dominant wrist. The corresponding mean total sleep time as calculated using a sleep polygraph was 133.0 min. Sleep/wake judgment by three levels of threshold values for the accelerometer showed that high-sensitive threshold showed relatively high specificity (0.452) compared with specificities by the low-sensitive threshold (0.249) or by the middle-sensitive threshold (0.358). The concordance correlation coefficients and 95% confidence intervals (in parenthesis) between the total sleep time judged by polygraph and low-sensitive, middle-sensitive, or high-sensitive accelerometer were 0.40 (0.26-0.51), 0.53 (0.38-0.65), and 0.64 (0.49-0.75), respectively. The Bland-Altman plot of the measurements showed higher agreement between the total sleep time by polygraph and by the accelerometer using the high-sensitive threshold.

CONCLUSIONS

From the result obtained in this study, the high-sensitive accelerometer showed the strongest agreement of total sleep time and sleep/wake judgment with the calculated value using the sleep polygraph.

Validation of a multi-sensor activity monitor for assessing sleep in children and adolescents

OBJECTIVE

To assess the validity of a multi-sensor activity monitor in estimating sleep and wake compared to polysomnography in children and adolescents.

METHODS

A total of 43 children and adolescents (29 boys, 14 girls), aged 7-17years (mean age [SD] = 11.0 [2.4] years) participated in the study. Participants wore the SenseWear Pro(3) Armband™ (SWA) body monitor (BodyMedia Inc) during an overnight polysomnographic assessment in a paediatric sleep laboratory. Sleep measures included sleep onset latency (SOL), wake after sleep onset (WASO), total sleep time (TST) and sleep efficiency (SE).

RESULTS

No systematic bias of the SWA was noted for any of the sleep measures assessed, but limits of agreement were wide and amounted to -76 to +58min for SOL, -75 to 102min for WASO, -109 to +99min for TST and -22 to +20% for SE. In addition, no effect of gender, age group (children versus adolescents) or overweight on the accuracy of the SWA was found.

CONCLUSIONS

The SenseWear Armband™ showed good agreement with polysomnography at the group level, while at the individual level rather, poor agreement between the two methods was observed. Consequently, at this point the use of the SWA in the clinical evaluation of sleep cannot be advocated.