Medical comorbidity of sleep disorders in children and adolescents

Food Consumption and Sleep Disturbances in 9-year-old Children

Objective  To assess the association of food consumption with sleep disturbances in 9-year-old children. Material and Methods  The present study is part of a larger cohort study named Predictors of Maternal and Infant Excess Body Weight (PREDI) that was conducted in the homes of the participants during the fourth study follow-up. Anthropometric assessment and demographic, socioeconomic, food consumption, and sleep data were obtained. The children's food consumption was evaluated using the Brazilian Food and Nutrition Surveillance System (SISVAN, in the Portuguese acronym). Sleep habits were assessed using the Sleep Disturbance Scale for Children to evaluate sleep pattern-related behaviors in children/adolescents aged 3 to 18 years. Data were self-reported by the mother and her child on the day of the visit. Logistic regression analysis was used to estimate the association of food consumption with sleep disturbances in children at 9 years of age. Results  Of the 142 children who participated in the study, 45.1% had sleep disturbances; most of them were boys (53.6%). The proportion of children with sleep disturbances was higher (55.6%) among children who did not consume fruits compared with those who ate fruits ( p  = 0.008). Logistic regression analysis revealed that the lack of fruit consumption was associated with sleep disturbances (OR = 2.26, p  = 0.023), even after adjustment for other predictors. Conclusion  We showed that the lack of fruit consumption is a predictor of sleep disturbances. Since fruit consumption had a protective effect on sleep disturbances at 9 years of age, encouraging the consumption of fiber-rich foods may contribute to preventing the establishment of sleep problems even in infants.

Associations between perinatal risk and physical health in pre-adolescence in the Adolescent Brain Cognitive Development (ABCD) Study®: the unexpected relationship with sleep disruption

BACKGROUND

To investigate relationships among different physical health problems in a large, sociodemographically diverse sample of 9-to-10-year-old children and determine the extent to which perinatal health factors are associated with childhood physical health problems.

METHODS

A cross-sectional study was conducted utilizing the Adolescent Brain Cognitive Development℠ (ABCD) Study (n = 7613, ages 9-to-10-years-old) to determine the associations among multiple physical health factors (e.g., prenatal complications, current physical health problems). Logistic regression models controlling for age, sex, pubertal development, household income, caregiver education, race, and ethnicity evaluated relationships between perinatal factors and childhood physical health problems.

RESULTS

There were significant associations between perinatal and current physical health measures. Specifically, those who had experienced perinatal complications were more likely to have medical problems by 9-to-10 years old. Importantly, sleep disturbance co-occurred with several physical health problems across domains and developmental periods.

CONCLUSION

Several perinatal health factors were associated with childhood health outcomes, highlighting the importance of understanding and potentially improving physical health in youth. Understanding the clustering of physical health problems in youth is essential to better identify which physical health problems may share underlying mechanisms.

IMPACT

Using a multivariable approach, we investigated the associations between various perinatal and current health problems amongst youth. Our study highlights current health problems, such as sleep problems at 9-to-10 years old, that are associated with a cluster of factors occurring across development (e.g., low birth weight, prenatal substance exposure, pregnancy complications, current weight status, lifetime head injury). Perinatal health problems are at large, non-modifiable (in this retrospective context), however, by identifying which are associated with current health problems, we can identify potential targets for intervention and prevention efforts.

Prevalence and Characteristics of Sleep Disorders in Children Aged 7-17: Insights from Parental Observations at the Dental Office

Sleep disorders (SD) in children is a topic of great relevance due to their impact on a child's general health. This has led us to study their prevalence and the factors that disturb them in the developing population. Using a validated Likert-type questionnaire, different behaviors observed by the parents during the different phases of their children's sleep were evaluated during the last 6 months. A total of 206 children between the ages of 7 and 17 who attended a dental office participated in the study. The prevalence of SD was 47.6%. There were no significant differences regarding the SD in relation to sex (p = 0.796). The mean total score for children aged 7 to 11 years old was 42.3 (±14.25) compared to 45.44 (±15.51) for the group consisting of children aged 12 to 17 years old, reporting a statistically significant difference among both age groups (p = 0.01). The most frequent disorder was related to initiating and maintaining sleep (64.9%) while the least prevalent were the respiratory sleep disorders (27.2%). Given the high prevalence of these disorders, it is necessary to intercept them during childhood and establish educational guidelines in this regard throughout primary care.

Consensus recommendations on sleeping problems in Phelan-McDermid syndrome

Early onset sleep problems and disorders are very common in individuals with Phelan-McDermid Syndrome (PMS) with rates of up to 90%. These sleep problems and disorders cannot be taken lightly. Not only do they have a major impact on the health, behaviour, functioning and learning opportunities of affected individuals, they can also have detrimental effects on the well-being and resilience of parents and caregivers, ultimately affecting the physical health, mental health and well-being of the whole social system. In this review we aim to understand the types and frequencies of sleeping problems in PMS as the basis for recommendations on their management and treatment and to provide general guidelines for clinicians and practitioners. We conducted an in-depth literature search, summarised findings, and participated in a series of consensus meetings with other consortium members - experts on PMS and stakeholders - to agree on guidelines and recommendations. In parallel, a world-wide survey was created and distributed amongst parents to include their perspective. Our literature search found only three articles specifically focused on sleeping problems in PMS, although some other articles mentioned prevalence and associated factors. Country-specific prevalence rates ranged between 24% and 46%, whereas our parental survey reported 59%. The main problems reported involved difficulty falling asleep and numerous night awakenings, with being restless in sleep, night-time incontinence, and tooth grinding also commonly reported. Only a small number of individuals had undergone a sleep study monitored by a specialist. Bedtime resistance normally decreases with age, but sleep-onset delay, sleep anxiety, parasomnias, problems falling and remaining asleep remain throughout lifespan, with total sleep time improving during adulthood. However, this improvement was also accompanied by a substantial increase in parasomnias. Ultimately, an increase in sleep disorders in children correlates with increased sleep disorders and daytime sleepiness in parents/caregivers. No study to date has focused on the underlying causes of sleeping problems in PMS, but comorbid mental health conditions, somatic causes, or (poly)pharmacy have been proposed as triggers for sleeping disturbances. Currently there is no PMS-specific treatment for sleeping problems, and current recommendations are mostly based on individuals with intellectual disability and/or neurodevelopmental conditions.

Allergic disease, sleep problems and psychological distress in children recruited from the general community

BACKGROUND

It is unclear which allergic disease is most strongly related to which sleep problem and whether sleep problems may mediate the association between allergic disease and psychological distress. There is also a need for more community-based studies using non-referred samples.

OBJECTIVE

To examine the association between individual allergic diseases and sleep problems and test whether the association between allergic disease and psychological distress is mediated through sleep problems.

METHODS

Parents of 1449 Australian children aged 6-10y recruited from the general community completed measures of sleep problems (Pediatric Sleep Survey Instrument), psychological distress (Strengths and Difficulties Questionnaire), and frequency of allergic disease.

RESULTS

Sleep and psychological distress scores were in the normal range. After controlling for co-existing allergic diseases: allergic rhinitis was associated with sleep routine problems, morning tiredness, night arousals, sleep disordered breathing and restless sleep; asthma with sleep routine problems, sleep disordered breathing and restless sleep; and eczema with restless sleep. Path analyses revealed that sleep problems mediated the association between asthma and allergic rhinitis but not eczema with psychological distress.

CONCLUSION

In this non-referred community sample, the frequency of sleep problems and psychological distress was lower than that typically reported in children referred to specialized centres. However, allergic rhinitis was associated with a broad range of sleep problems and to a lesser extent in children with asthma and least in children with eczema. Path analysis revealed that the association between allergic disease and psychological distress was mediated through sleep problems highlighting the importance of assessing sleep health in children with allergic disease.

Insomnia - A Heterogenic Disorder Often Comorbid With Psychological and Somatic Disorders and Diseases: A Narrative Review With Focus on Diagnostic and Treatment Challenges

Patients with insomnia complain of problems with sleep onset or sleep maintenance or early morning awakenings, or a combination of these, despite adequate opportunity and circumstances for sleep. In addition, to fulfill the diagnostic criteria for insomnia the complaints need to be associated with negative daytime consequences. For chronic insomnia, the symptoms are required to be present at least 3 days per week for a duration of at least 3 months. Lastly, for insomnia to be defined as a disorder, the sleep complaints and daytime symptoms should not be better explained by another sleep disorder. This criterion represents a diagnostic challenge, since patients suffering from other sleep disorders often complain of insomnia symptoms. For instance, insomnia symptoms are common in e.g., obstructive sleep apnea and circadian rhythm sleep-wake disorders. It may sometimes be difficult to disentangle whether the patient suffers from insomnia disorder or whether the insomnia symptoms are purely due to another sleep disorder. Furthermore, insomnia disorder may be comorbid with other sleep disorders in some patients, e.g., comorbid insomnia and sleep apnea (COMISA). In addition, insomnia disorder is often comorbid with psychological or somatic disorders and diseases. Thus, a thorough assessment is necessary for correct diagnostics. For chronic insomnia disorder, treatment-of-choice is cognitive behavioral therapy, and such treatment is also effective when the insomnia disorder appears comorbid with other diagnoses. Furthermore, studies suggest that insomnia is a heterogenic disorder with many different phenotypes or subtypes. Different insomnia subtypes may respond differently to treatment, but more research on this issue is warranted. Also, the role of comorbidity on treatment outcome is understudied. This review is part of a Research Topic on insomnia launched by Frontiers and focuses on diagnostic and treatment challenges of the disorder. The review aims to stimulate to more research into the bidirectional associations and interactions between insomnia disorder and other sleep, psychological, and somatic disorders/diseases.

Adolescents' sleep quality in relation to peer, family and school factors: findings from the 2017/2018 HBSC study in Flanders

PURPOSE

While a multitude of studies focused on biological and behavioral determinants of adolescents' sleep quality, a paucity of research examined the impact of social factors. The current study therefore examines the relationship between adolescents' sleep quality and peer, family and school factors.

METHODS

Data of Flemish participants in the 2017/2018 Health Behavior in School-aged Children survey (HBSC) were used, which is representative of the adolescent population (11-18 years) in Flanders. Adolescents' sleep quality was linked to individual-level data on peer relationships (i.e., peer support), family relationships (i.e., family support, perceived family wealth, caregiving responsibilities) and school relationships (i.e., teacher support, school support, school pressure) and contextual-level data on the school culture. Three-level multilevel models were fitted to account for the clustering of individuals (N = 8153) within classes (N = 769) and classes within schools (N = 177).

RESULTS

The individual-level results indicated that adolescents' sleep quality was positively related to family support, teacher support, student support and perceived family wealth. In contrast, adolescents' sleep quality was negatively related to caregiving responsibilities and school pressure. In addition, the contextual-level results pointed out that adolescents tended to report better sleep quality in less-demanding schools.

CONCLUSION

These findings highlight the need to consider social factors in promoting better sleep in adolescence.

Association between snoring and heart rate variability in adolescents: effects of gender and insufficient sleep

PURPOSE

We explored the association between subjective snoring frequency and heart rate variability (HRV) in a healthy adolescent population.

METHODS

A total of 102 healthy adolescents were recruited from high schools in South Korea, and reported their sleep habits and snoring frequency. HRV was assessed to indirectly measure autonomic function. We assessed correlations between snoring frequency and HRV indices. We also investigated the effects of sex and behaviorally induced insufficient sleep syndrome (BISS) on the associations between HRV parameters and snoring frequency.

RESULTS

Overall, significant correlations were apparent between snoring frequency and HRV indices including the standard deviation of the normal-to-normal intervals (SDNN) and the low-frequency/high-frequency (LF/HF) ratio. Associations were more evident in males and those with BISS compared to females and those without BISS.

CONCLUSIONS

Our findings suggest that snoring changes autonomic nervous system (ANS) activity in adolescents; the changes are more dramatic in males and those with insufficient sleep.

The Importance of Sleep Hygiene in Polycystic Ovary Syndrome from the View of Iranian Traditional Medicine and Modern Medicine

Polycystic ovary syndrome (PCOS) is known as the most common hormonal disorder in women at reproductive age. Recent studies have revealed a high prevalence of sleep disorders in PCOS, suggesting that it is an amendable factor for these patients; however, the sleep was not considered in their treatment plan. According to the Iranian traditional medicine (ITM), sleep is an important item in the lifestyle modification of all diseases. The aim of this study is to determine the importance of sleep hygiene in PCOS from the view of ITM and Modern Medicine. In this study, some keywords about “sleep and PCOS” were searched in medical databases and some ITM books. Lifestyle modification is one of the first steps in treatment of patients with PCOS in which the emphasis will be mainly on exercise and diet. Despite proof of the high prevalence of sleep disorders in these patients, modification of sleep is not considered in their lifestyle. ITM as a holistic medicine emphasizes on lifestyle modification under the title of “Settah-e-Zaruria” (In Persian), the six essential schemes for the prevention and treatment of all diseases. Management of sleep is one of these schemes. There are many advices about sleep hygiene in both ITM and modern medicine. It seems that lifestyle modification should be expanded in PCOS patients to include more options, and sleep hygiene should be considered in their lifestyle alongside food and exercise.

Association between Sleep and Body Weight: A Panel Data Model Based on a Retrospective Longitudinal Cohort of Chinese Infants

The focus of this article is on sleep duration and sleep problems in infants and their association with body weight. A retrospective birth cohort of 519 infants was enrolled in a community-based study conducted in Changsha, China. Infant weight and other health-related information were collected during regular standard checkups at the Community Health Service Centers when infants were 1, 3, 6, 8, and 12 months old. The sleep duration and sleep problems of infants were assessed by maternal self-reports. Panel data model was used to evaluate the association of sleep duration and sleep problems with infant body weight. Significant relevance between self-reported sleep duration and weight of infants has been reported in the literature tested by the fixed effects model (p < 0.01). However, this study indicated that sleep problems of infants had no effect on their weight (p = 0.151), after adjusting feeding patterns and socioeconomic factors of their families. This paper argues that, as a potentially modifiable risk factor, infant sleep duration deserves more attention from their parents and families in order to prevent and control overweight or obesity in infants as well as reducing the incidence of obesity in adults.

A Single Arm Pilot Trial of Brief Cognitive Behavioral Therapy for Insomnia in Adolescents with Physical and Psychiatric Comorbidities

STUDY OBJECTIVES

The majority of adolescents with chronic insomnia have physical health or psychiatric comorbidities; insomnia is also associated with greater negative daytime symptoms (e.g., depressive symptoms) and reduced overall health-related quality of life (HRQOL). However, to date, there has been limited attention to treatment of insomnia in this population. The purpose of this study was to determine the preliminary efficacy of a brief cognitive behavioral therapy for insomnia (CBT-I) intervention on sleep, psychological symptoms, and HRQOL outcomes in adolescents with insomnia and co-occurring physical or psychiatric comorbidities.

METHODS

We conducted a single arm pilot trial in which 40 youth (mean age = 14.93, standard deviation = 1.89) with insomnia and physical or psychiatric comorbidities (e.g., depression, chronic pain, anxiety, gastrointestinal problems) received CBT-I in four individual treatment sessions over 4 to 6 w. Adolescents completed 7 days of wrist actigraphy and self-report measures of insomnia, sleep quality and behaviors, psychological symptoms, and HRQOL outcomes at pretreatment, immediate posttreatment, and 3-mo follow-up.

RESULTS

CBT-I was associated with improvements in self-reported measures of sleep including insomnia symptoms, sleep quality, sleep hygiene, pre-sleep arousal, and sleep onset latency. Psychological symptoms and HRQOL also improved. Effects were generally sustained at 3-mo follow-up.

CONCLUSIONS

CBT-I may be efficacious for adolescents with co-occurring physical and mental health comorbidities; future randomized controlled trials are needed to test the effect of CBT-I on sleep, psychological symptoms, and HRQOL and to evaluate maintenance of treatment effects over longer time periods.

Infant sleep problems and childhood overweight: Effects of three definitions of sleep problems

Sleep problems have been defined using a variety of definitions. No study has assessed the longitudinal association between infant sleep problems and childhood overweight or obesity using existing definitions of sleep problems. This study used longitudinal data (n = 895) from the multi-site Study of Early Child Care and Youth Development (SECCYD) to investigate the effects of infant sleep problems on childhood weight status in Grade 6. Infants with sleep problems in Phase I (1991) and with complete data through Phase III (2004) of SECCYD were included. Sleep problems were assessed using maternal reports of night wakings and duration of a waking episode. Sleep problems were defined using Richman (1981), Lozoff et al. (1985), and Zuckerman et al. (1987) definitions. Multinomial logistic regression was used to examine the association between sleep problems during infancy and childhood weight status in Grade 6 while controlling for birth weight, race, sex, breastfeeding, maternal poverty, family structure, and maternal education. After adjusting for all covariates, children with a history of sleep problems were found to be overweight in Grade 6 using Zukerman et al. (Odds ratio (OR) = 1.68; 95% confidence interval (CI): 1.11-2.55) and Richman (OR = 1.76; 95% CI: 1.05-2.97) definitions, but not using Lozoff et al.

DEFINITION

Infant sleep problems were not found to be associated with being obese. The study found differential effects of infant sleep problems on childhood overweight in Grade 6 per different definitions of sleep problems. Findings highlight the need to construct a single definition of infant sleep problems.

Periodontal Disease Is Associated with Insomnia among Victims of the Great East Japan Earthquake: A Panel Study Initiated Three Months after the Disaster

In March 2011, the Great East Japan Earthquake (GEJE), which was followed by a devastating tsunami, destroyed the societal and the public hygiene systems in Japanese coastal areas. Insomnia, the greatest issue among disaster victims, has detrimental effects on both physical and psychological health. Periodontitis causes chronic discomfort and inflammation, and little is known about its impact on insomnia. Three months after the earthquake, a health panel survey was conducted over four surveys, till September 2013, in which information regarding 8,015 adults was collected and used. In addition to the heath-related questionnaire, other variables including subjective symptoms of oral diseases were recorded, and the Athens Insomnia Scale was used to evaluate the severity of insomnia. The association between insomnia and periodontal disease was examined using multilevel logistic models on the panel data, after adjusting for sex, age, economic status, comorbidities, body mass index, post-traumatic stress reactions, habitual smoking and alcohol drinking, and the Kessler Psychological Distress Scale score. In addition to the higher prevalence of insomnia among GEJE victims, significant association was revealed between insomnia and gum problems (OR = 2.16, 95% CI = 1.43-3.26), and difficulty chewing (OR = 2.22, 95% CI = 1.40-3.51), after adjusting for all covariates. The present study revealed significant association between insomnia and periodontal disease among GEJE victims. This indicated that together, integrated oral health care for disaster victims would contribute not only to prevention of oral infectious diseases, but may also help alleviate other problems caused by these harmful events.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Sleep disordered breathing risk in childhood cancer survivors: an exploratory study

BACKGROUND

Sleep disordered breathing (SDB) is emerging as a significant health condition for children. The purpose of this study is to evaluate SDB symptoms in childhood cancer survivors and identify associations with quality of life (QOL) and psychological symptoms.

PROCEDURE

A sample of 62 survivors aged 8-18 years were recruited during routine survivorship visits. All subjects and their parents completed questionnaires to evaluate sleep, QOL and psychological symptoms; scales included were: Pediatric Sleep Questionnaire, Sleep Disordered Breathing Subscale (PSQ-SDBS), Pediatric Quality of Life Inventory (PedsQL) and Depression Anxiety Stress Scale (DASS-21). Continuous data were used for all scales and a threshold score of >0.33 on the PSA-SDBS was used to identify risk of SDB. The relationships between measures of sleep and independent variables were examined using Pearson correlations and multiple linear regression models for significant associations.

RESULTS

Of the 62 subjects enrolled, underlying diagnoses included 29 leukemias, 30 solid tumors and 3 non-malignant diseases. Nineteen percent of subjects were identified as having SDB risk on the PSQ-SDBS. The lowest mean PedsQL subscale score for parent and child ratings were school QOL; Parent mean 73(±SD 19) and Child mean 71(±SD 20). The severity of SDB per the PSQ was significantly associated with reduced total and school QOL which remained significant after adjusting for stress.

CONCLUSIONS

Symptoms suggestive of SDB are common in childhood cancer survivors with negative implications for overall quality of life and school performance.

Separating bedtime rest from activity using waist or wrist-worn accelerometers in youth

Recent interest in sedentary behavior and technological advances expanded use of watch-size accelerometers for continuous monitoring of physical activity (PA) over extended periods (e.g., 24 h/day for 1 week) in studies conducted in natural living environment. This approach necessitates the development of new methods separating bedtime rest and activity periods from the accelerometer recordings. The goal of this study was to develop a decision tree with acceptable accuracy for separating bedtime rest from activity in youth using accelerometer placed on waist or wrist. Minute-by-minute accelerometry data were collected from 81 youth (10-18 years old, 47 females) during a monitored 24-h stay in a whole-room indirect calorimeter equipped with a force platform covering the floor to detect movement. Receiver Operating Characteristic (ROC) curve analysis was used to determine the accelerometer cut points for rest and activity. To examine the classification differences, the accelerometer bedtime rest and activity classified by the algorithm in the development group (n = 41) were compared with actual bedtime rest and activity classification obtained from the room calorimeter-measured metabolic rate and movement data. The selected optimal bedtime rest cut points were 20 and 250 counts/min for the waist- and the wrist-worn accelerometer, respectively. The selected optimal activity cut points were 500 and 3,000 counts/min for waist and wrist-worn accelerometers, respectively. Bedtime rest and activity were correctly classified by the algorithm in the validation group (n = 40) by both waist- (sensitivity: 0.983, specificity: 0.946, area under ROC curve: 0. 872) and wrist-worn (0.999, 0.980 and 0.943) accelerometers. The decision tree classified bedtime rest correctly with higher accuracy than commonly used automated algorithm for both waist- and wrist-warn accelerometer (all p<0.001). We concluded that cut points developed and validated for waist- and wrist-worn uniaxial accelerometer have a good power for accurate separation of time spent in bedtime rest from activity in youth.

Developmental Immunotoxicity, Perinatal Programming, and Noncommunicable Diseases: Focus on Human Studies

Developmental immunotoxicity (DIT) is a term given to encompass the environmentally induced disruption of normal immune development resulting in adverse outcomes. A myriad of chemical, physical, and psychological factors can all contribute to DIT. As a core component of the developmental origins of adult disease, DIT is interlinked with three important concepts surrounding health risks across a lifetime: (1) the Barker Hypothesis, which connects prenatal development to later-life diseases, (2) the hygiene hypothesis, which connects newborns and infants to risk of later-life diseases and, (3) fetal programming and epigenetic alterations, which may exert effects both in later life and across future generations. This review of DIT considers: (1) the history and context of DIT research, (2) the fundamental features of DIT, (3) the emerging role of DIT in risk of noncommunicable diseases (NCDs) and (4) the range of risk factors that have been investigated through human research. The emphasis on the human DIT-related literature is significant since most prior reviews of DIT have largely focused on animal research and considerations of specific categories of risk factors (e.g., heavy metals). Risk factors considered in this review include air pollution, aluminum, antibiotics, arsenic, bisphenol A, ethanol, lead (Pb), maternal smoking and environmental tobacco smoke, paracetamol (acetaminophen), pesticides, polychlorinated biphenyls, and polyfluorinated compounds.

Sleep duration and adiposity in older adolescents from Otago, New Zealand: relationships differ between boys and girls and are independent of food choice

Background

While relationships between sleep and BMI have been extensively studied in younger children the effect of sleep duration on adiposity in adolescents, who are undergoing rapid growth periods, is less well known. There is also a lack of consistent evidence on the role of sleep on other measures of adolescent body composition which may be more reflective of health than BMI in this age group. Previous research investigating whether these relationships differ between sexes is also inconsistent. Therefore the objective of this study was to investigate relationships between sleep duration and multiple body composition measures in older adolescents and to investigate if these relationships differ between boys and girls.

Methods

A web-based cross-sectional survey and anthropometric measurement of 685 adolescents (mean age 15.8 years) from 11 schools in Otago, New Zealand. Height and weight were measured by trained researchers and fat mass and fat-free mass were estimated using bio-impedance. Generalised estimating equations were used to examine associations between sleep duration and the following body composition measures: BMI, waist circumference (WC), waist-to-height ratio (WHtR), fat mass index (FMI), and fat-free mass index (FFMI). Analyses were adjusted for ethnicity, deprivation, the number of screens in the bedroom and fruit and vegetable consumption.

Results

When data from all participants were analysed together, no significant relationships were seen between sleep duration and any body composition measure but significant sex interactions were seen. An hour increase in average nightly sleep duration in boys only was associated with decreases of 1.2% for WC, 0.9% for WHtR, 4.5% for FMI and 1.4% for FFMI in multivariate models. Similar results were seen for weekday and weekend night sleep duration.

Conclusions

Sex specific factors may play a role in relationships between sleep and body composition in older adolescents. The results in boys were most pronounced for FMI, a measure of total adiposity, which suggests that insufficient sleep in adolescent boys may affect fat mass more than lean mass and that the use of measures such as BMI may result in an under-estimation of relationships.

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

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