Falling asleep: the determinants of sleep latency

A population-based study exploring association of parasomnia symptoms with sleep onset delay among school-aged children

OBJECTIVE

Parasomnia is potentially implicated in sleep pattern and sleep architecture, however, evidence is quite limited. This study aimed to investigate the association between parasomnia symptoms and sleep onset delay among children through a large epidemiological study.

METHODS

Two rounds of cross-sectional studies were conducted among 21,704 children aged 3-11; one taking place in Shanghai and the other in Sanya, Hainan province. Children's sleep characteristics were evaluated using the Children's Sleep Habits Questionnaire (CSHQ). Propensity score matching was adopted to balance the difference of covariates, and the logistic regression models were implemented to examine the associations between parasomnia symptoms and sleep onset delay.

RESULTS

A total of 38.2 % of children had sleep onset delay. Parasomnias, especially non rapid eye movement (NREM) and rapid eye movement (REM) parasomnia symptoms, were associated with an increased risk of sleep onset delay (Sleep Walking: OR = 1.55; Sleep Terror: OR = 1.34; Nightmare: OR = 1.37, all p˂0.001). The similar findings were observed in stratified analyses according to sleep duration, and the association was pronounced in sleep sufficiency group (Sleep Walking: OR = 1.62; Sleep Terror: OR = 1.35; Nightmare: OR = 1.35, all p˂0.001). Moreover, a dose-dependent pattern was observed, in which cumulative parasomnia symptoms were associated with increasing risk of sleep onset delay (2 symptoms: OR = 1.19; ≥3 symptoms: OR = 1.40; by comparison with ≤1 symptom). All these findings were also similarly observed in the propensity score matching sample. Moreover, the associations were generally established in both Shanghai and Sanya children.

CONCLUSIONS

Parasomnia symptoms were associated with a higher risk of sleep onset delay independently of sleep duration among children. More studies are needed to enrich the current evidence, thus further clarifying the association and interaction among different sleep parameters.

The effect of exercise on sleep habits of children with type 1 diabetic: a randomized clinical trial

BACKGROUND

Adequate sleep and exercise are important components of the human lifestyle. Paying attention to these two factors is very important to improve the condition of children with type 1 diabetes. Therefore, this study aimed to investigate the effect of exercise on sleep habits in children with type 1 diabetes.

MATERIAL & METHODS

62 children with type 1 diabetes participated in this clinical trial. They will be divided into the intervention group (31) and the control group (31). Sleep habits were measured using the Children's Sleep Habits Questionnaire (CSHQ). All children's parents completed the CSHQ. The intervention for the experimental group consisted of 8 weeks of regular exercise program. The exercise program was prepared as an educational video and provided to parents. Paired sample t-test and ANCOVA test were used with SPSS 23.

RESULTS

62 children with an average age of 9.32 ± 2.02 were studied. Fifty-four and eight% of the children were girls and the rest were boys. The analysis of the variance test showed a significant difference (F = 144.72, P ≤ 0.01) between the average score of the sleep habits of the control group (62.45 ± 5.12) and the experimental group (47.06 ± 4.39).

CONCLUSION

Sleep habits in the experimental group improved after 8 weeks of exercise training using educational videos. Exercise as a non-pharmacological treatment is an effective way to manage diabetes and improve sleep quality in diabetic children.

Neighborhood predictors of short sleep duration and bedtime irregularity among children in the United States: results from the 2019-2020 National Survey of Children's Health

BACKGROUND

Environmental factors may contribute to short sleep duration and irregular bedtime in children. Neighborhood factors and children's sleep duration and bedtime regularity remain a less investigated area. The aim of this study was to investigate the national and state-level proportions of children with short sleep duration and irregular bedtime and their neighborhood predictors.

METHODS

A total of 67,598 children whose parents completed the National Survey of Children's Health in 2019-2020 were included in the analysis. Survey-weighted Poisson regression was used to explore the neighborhood predictors of children's short sleep duration and irregular bedtime.

RESULTS

The prevalence of short sleep duration and irregular bedtime among children in the United States (US) was 34.6% [95% confidence interval (CI) = 33.8%-35.4%] and 16.4% (95% CI = 15.6%-17.2%) in 2019-2020, respectively. Safe neighborhoods, supportive neighborhoods, and neighborhoods with amenities were found to be protective factors against children's short sleep duration, with risk ratios ranging between 0.92 and 0.94, P < 0.05. Neighborhoods with detracting elements were associated with an increased risk of short sleep duration [risk ratio (RR) = 1.06, 95% CI = 1.00-1.12] and irregular bedtime (RR = 1.15, 95% CI = 1.03-1.28). Child race/ethnicity moderated the relationship between neighborhood with amenities and short sleep duration.

CONCLUSIONS

Insufficient sleep duration and irregular bedtime were highly prevalent among US children. A favorable neighborhood environment can decrease children's risk of short sleep duration and irregular bedtime. Improving the neighborhood environment has implications for children's sleep health, especially for children from minority racial/ethnic groups.

Sleep and Its Disturbance in Parents of Children and Adolescents with Epilepsy: A Systematic Review and Meta-Analysis

Sleep disturbances are commonly reported by parents of children and adolescents with epilepsy. However, evidence synthesis including quality and quantity of sleep in parents of children and adolescents with epilepsy is lacking. This systematic review and meta-analysis was conducted to quantify pooled mean estimates of parental sleep variables and to determine the prevalence of sleep disturbances in parents of children and adolescents with epilepsy. Five electronic databases, PubMed, Medline, Embase, PsychINFO, and CINAHL, were systematically searched from inception to September 2021. Eleven observational studies examining parents of pediatric patients aged <18 years with epilepsy using a quantitative measure of sleep duration, sleep quality, or sleep disturbance were reviewed. Our results showed that the pooled nocturnal sleep duration was 5.93 hours (95% CI: 4.64 to 7.21 hours). Overall sleep quality as estimated by the bias-adjusted pooled Pittsburgh Sleep Quality Index total score was 6.65 (95% CI: 5.98 to 7.33). Parents of children with epilepsy had significantly higher Pittsburgh Sleep Quality Index total scores compared to parents of healthy children (differences in means 1.84, 95% CI: 1.29 to 2.39). The pooled estimated prevalence of parental sleep disturbances was 58.1% (95% CI: 45.7% to 69.6%). Our findings demonstrate a high prevalence of sleep disturbances with poor sleep quality and substantial reductions in sleep time in parents of children and adolescents with epilepsy. Healthcare professionals in pediatric neurology clinics should proactively initiate screening for sleep disturbances in parents of children and adolescents with epilepsy and refer parents to a sleep specialist when necessary.

Abnormal alterations of regional spontaneous neuronal activity and functional connectivity in insomnia patients with difficulty falling asleep: a resting-state fMRI study

BACKGROUND

Insomnia disorder (ID) seriously affects people's daily life. Difficulty falling asleep is the most commonly reported complaint in patients with ID. However, the mechanism of prolonged sleep latency (SL) is still obscure. The aim of our present study was to investigate the relationship between prolonged SL and alterations in spontaneous neural activity and brain functional connectivity (FC) in ID patients using functional magnetic resonance imaging (fMRI).

METHODS

A total of 52 insomniacs with difficulty falling asleep and 30 matched healthy controls (HCs) underwent resting-state fMRI. The amplitude of low-frequency fluctuation (ALFF) was measured and group differences were compared. The peak areas with significantly different ALFF values were identified as the seed regions to calculate FC to the whole brain. SL was assessed by a wrist actigraphy device in ID patients. The Pittsburgh Sleep Quality Index (PSQI), Hamilton Anxiety Rating Scale (HAMA), and Hyperarousal Scale (HAS) were evaluated in both ID patients and HCs. Finally, correlation analyses were performed between the clinical features and FC/ALFF values.

RESULTS

ID patients showed higher PSQI, HAMA, HAS scores than HCs. The functional MRI results indicated increased ALFF value in the left insula and right amygdala and decreased ALFF value in the right superior parietal lobe (SPL) in ID patients. The seed-based FC analysis demonstrated increased FC between the left insula and the bilateral precentral gyrus and FC between the right amygdala and the left posterior cingulate cortex (PCC) in patients with ID. Correlation analysis indicated that the increased FC value of the right amygdala-left PCC was positively correlated with SL measured by actigraphy.

CONCLUSION

This study revealed abnormal regional spontaneous fluctuations in the right amygdala, left insula, and right SPL, as well as increased FC in the left insula-precentral and right amygdala-left PCC. Moreover, the prolonged SL was positively correlated with the abnormal FC in the right amygdala-left PCC in ID patients. The current study showed the correlation between prolonged SL and the abnormal function of emotion-related brain regions in ID patients, which may contribute to a better understanding of the neural mechanisms underlying difficulty falling asleep in patients with ID.

CLINICAL TRIAL REGISTRATION

http://www.chictr.org.cn ., ChiCTR1800015282. Registered on 20th March 2018.

Effects of a time-use intervention in isolated patients with coronavirus disease 2019: A randomized controlled study

OBJECTIVE

Patients with coronavirus disease experience deterioration in occupational balance and mental health. The primary objective of this study was to determine the effectiveness of a time-use intervention on the occupational balance of isolated patients with coronavirus disease. Its impact on secondary outcomes including mental health and quality of life was also assessed.

METHODS

This randomized controlled clinical trial was conducted in a single community-based hospital. Forty-one patients (19 in the experimental group and 22 in the control group) with coronavirus disease were recruited between February 1, 2021, and March 19, 2021. Participants were randomly assigned to receive a time-use intervention or education on self-activity. The time-use intervention is to plan a daily routine to engage in meaningful occupations. It consisted of 4 steps: time-use analysis, occupation selection, arrangement of activities and practice, and occupational therapist intervention. The control group was educated on self-activity and spent time autonomously.

OUTCOMES AND MEASURES

The primary outcome was occupational balance, evaluated using the Korean version of the Life Balance Inventory. Secondary outcomes were mental health and quality of life assessed using the Korean version of the Patient Health Questionnaire-9, Korean Form of Zung's Self-Rating Anxiety Scale, Korean version of the Insomnia Severity Index, Multidimensional State Boredom Scale-8, Fear of Coronavirus Disease: Korean version of the Fear of Coronavirus Disease Scale, and World Health Organization Quality of Life Assessment Instrument-BRIEF. Outcome measures were evaluated at admission and discharge.

RESULTS

The time-use intervention significantly improved occupational balance (F = 14.12, p < .001) and all other measures of depression, anxiety, boredom, fear, and quality of life. Conversely, the control group showed a worsening pattern for all measures.

CONCLUSION

The time-use intervention is effective for improving occupational balance, mental health, and quality of life in patients with coronavirus disease.

Psychological rehabilitation for isolated patients with COVID-19 infection: A randomized controlled study

OBJECTIVE

To improve the mental health of isolated patients with COVID-19 by face-to-face psychological rehabilitation program.

DESIGN

Randomized controlled study.

SETTING

Single community-based hospital.

PARTICIPANTS

109 patients (52 in experimental group, 57 in control group) with COVID-19 were recruited from May 27 to September 17, 2021.

INTERVENTIONS

A psychological rehabilitation program that consists of education, craft, and physical activity. The activity program was provided by a multidisciplinary rehabilitation team of doctors, nurses, occupational therapists, and physical therapists. The purpose of the education was to provide accurate information about COVID-19, and craft and physical activity were for improving physical health, occupational balance, participation in activities, and reducing boredom.

MAIN OUTCOME MEASURES

The primary outcome was degree of anxiety assessed using the Zung Self-Rating Anxiety Scale (SAS). Secondary outcomes were severity of depression, and quality of sleep assessed using the Zung Self-Rating Depression Scale (SDS), Patient Health Questionnaire-9 (PHQ-9), Visual Analysis Scale (VAS), and the Korean version of the Insomnia Severity Index (ISI-K).

RESULTS

Isolated patients complained of anxiety, depression, and insomnia the most in the early stages of hospitalization and isolation. In addition, the psychological rehabilitation program significantly improved mental health scale, including scores of SAS (F = 12.46, p = .001), SDS (F = 6.76, p = .01), and ISI-K (F = 4.41, p = .04).

CONCLUSIONS

The psychological rehabilitation program is effective for improving anxiety, depression, and quality of sleep for isolated patients with COVID-19.

Movement behaviors during COVID-19 among Latin American/Latino toddlers and pre-schoolers in Chile, Mexico and the US

Movement behaviors (physical activity, sedentary behavior, and sleep) have been impacted by the COVID-19 pandemic. We report changes in and factors that influenced movement behaviors during COVID-19 among Latin American/Latino children aged 1 to 5 years in Chile, Mexico, and the USA. We conducted a cross-sectional study between April and August 2020. Caregivers of 4,136 children (mean age [SD], 3.1 [1.4] years; 51% boys) reported family and household characteristics and changes in their child's movement behaviors. The proportion of children who met the WHO Guidelines decreased significantly in all countries, with the largest declines in meeting the physical activity and screen time guidelines. Factors associated with negative changes in movement behaviors were being an older child, unable to attend an early childhood education and care service, higher parental education levels, not having the opportunity to play with someone, and not having access to spaces to play. The findings highlight the need to minimize disparities faced by families by providing access to early childhood education and care and safe places for children to play.

Subcortical and Cerebellar Neural Correlates of Prodromal Alzheimer’s Disease with Prolonged Sleep Latency

Background: Despite the important associations among sleep, Alzheimer’s disease (AD), subcortical structures, and the cerebellum, structural and functional magnetic resonance imaging (MRI) with regard to these regions and sleep on patients in AD trajectory are scarce. Objective: This study aimed to evaluate the influence of prolonged sleep latency on the structural and functional alterations in the subcortical and cerebellar neural correlates in amyloid-β positive amnestic mild cognitive impairment patients (Aβ+aMCI). Methods: A total of 60 patients with aMCI who were identified as amyloid positive ([18F] flutemetamol+) were recruited in the study, 24 patients with normal sleep latency (aMCI-n) and 36 patients prolonged sleep latency (aMCI-p). Cortical thickness and volumes between the two groups were compared. Volumetric analyses were implemented on the brainstem, thalamus, and hippocampus. Subcortical and cerebellar resting state functional connectivity (FC) differences were measured between the both groups through seed-to-voxel analysis. Additionally, group x Aβ interactive effects on FC values were tested with a general linear model. Result: There was a significantly decreased brainstem volume in aMCI-p subjects. We observed a significant reduction of the locus coeruleus (LC) FC with frontal, temporal, insular cortices, hippocampus, and left thalamic FC with occipital cortex. Moreover, the LC FC with occipital cortex and left hippocampal FC with frontal cortex were increased in aMCI-p subjects. In addition, there was a statistically significant group by regional standardized uptake value ratio interactions discovered in cerebro-cerebellar networks. Conclusion: The aforementioned findings suggest that prolonged sleep latency may be a detrimental factor in compromising structural and functional correlates of subcortical structures and the cerebellum, which may accelerate AD pathophysiology.

Physical Activity and Executive Function in Children With ADHD: The Mediating Role of Sleep

This study examined the mediating role of sleep in the relationship between physical activity and executive function in children with attention deficit hyperactivity disorder (ADHD). Fifty-six children with ADHD were recruited from Shenzhen Children's Hospital. Participants wore an accelerometer for seven consecutive days to measure physical activity and sleep quality. Activity counts were analyzed to measure moderate-to-vigorous physical activity (MVPA). Four sleep parameters, including sleep latency (SL), sleep efficiency, total sleep time, and wake after sleep onset were recorded from the actigraph. Three core executive functions, inhibitory control; working memory (WM); and cognitive flexibility (CF), were assessed from computer-based tasks: the flanker task, and the Tower of London and Trail Making Tests, respectively. The regression results showed that MVPA was negatively associated with SL (-0.169; 95%CI [-0.244, -0.112]). WM (total scores) was positively related to MVPA (0.028, 95%CI [0.008, 0.048]), but negatively related to SL (-0.105, 95%CI [-0.167, -0.030]). CF (part B errors) was negatively associated with MVPA (-0.031, 95%CI [-0.055, -0.005]) and positively correlated with SL (0.184, 95%CI [0.092, -0.260]). The indirect effect of SL was found for MVPA and WM (0.018, 95%CI [0.015, 0.034]), supporting the indirect partial mediation. Similarly, the indirect effect of SL was found between MVPA and CF (-0.031, 95%CI [-0.060, -0.012]), supporting the indirect partial mediation. The mediating role of SL in children with ADHD suggests that the intensity of physical activity plays a key role in linking sleep quality and executive function in this group.

The impact of social networks on sleep among a cohort of college students

Background

Sleep duration and quality are associated with physical and mental wellbeing. This paper examines social network effects on individual level change in the sleep quantity and quality from late adolescence to emerging adulthood and its associated factors, including the influence of peers on sleep behavior and the impact of changes in network size.

Methods

We use sleep data from 619 undergraduates at the University of Notre Dame obtained via Fitbit devices as part of the NetHealth project. The data were collected between August 16, 2015 and May 13, 2017. We model trends in sleep behaviors using latent growth-curve models.

Results

Controlling for the many factors known to impact sleep quantity and quality, we find two social network effects: increasing network size is associated with less sleep and a student's sleep levels are influenced by his or her peers. While we do not find any consistent decline in sleep quantity over the 637 days, daily fluctuations in sleep quantity are associated with changes in network size and the composition of a student's network. As a student's network gets bigger, s/he sleeps less, and when a student's contacts sleep more (or less) than s/he does, the student becomes more like his or her contacts and sleeps more (or less).

Conclusions

Social networks can and do impact sleep, especially sleep quantity. In contexts where students want to have larger networks, the difficulties of increasing network size and maintaining larger networks negatively impact sleep. Because of peer influence, the effectiveness of interventions designed to improve sleep practices could be increased by leveraging student social networks to help diffuse better sleep habits.

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The sleep habits of 619 undergraduates were traced with Fitbit devices for 637 days.

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Their sleep quantity measures were relatively stable but affect by peers.

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Their sleep quality was slightly getting worse but not affected by peers.

Opportunities to improve sleep of children exposed to interpersonal violence: A social-ecological perspective

Over 25% of U.S. children are witness to traumatic intrafamilial or community violence each year, and sleep medicine and developmental research jointly suggest that trauma-exposed youth experience more sleep disturbance than their non-exposed counterparts. Sleep medicine literature emphasizes physical and social environmental factors affecting sleep, and trauma literature underscores children's seeking out physically and emotionally safe and predictable environments during trauma recovery. This study employed a hermeneutic phenomenological framing to explore the lived experiences of 65 violence-exposed children and families, and to examine how youths' social and physical sleep environments facilitated or impeded sleep in the aftermath of trauma. Children's sleep experiences following violence exposure shared two primary essences of experience: a) navigating external threats that agitated sleep after trauma; and b) exercising agency over sleep and related environments to restabilize emotional security. Clinicians and social services coordinators working with children and families are uniquely positioned to indicate sleep assessments as part of treatment following trauma, and to also facilitate identification of tangible, sleep-supportive and changeable factors in sleep environments.

Sleep and the General Behavior of Infants and Parents during the Closure of Schools as a Result of the COVID-19 Pandemic: Comparison with 2019 Data

This study compared cross-sectional data from online surveys describing the sleep behavior of infants and caregivers in March 2020 (the school closure period during the early stages of the COVID-19 pandemic; n = 295, 23.8 ± 3.8 months old) and March 2019 (before the pandemic; n = 2017, 24.2 ± 3.8 months old). In comparing those two points in time, no significant differences were found in wake-up times (2019: 7:19 ± 0:46 am vs. 2020: 7:18 ± 0:47 am, p = 0.289), bedtimes (21:01 ± 0:48 pm vs. 21:04 ± 0:53 pm, p = 0.144), or nocturnal sleep times (593.7 ± 43.9 min vs. 588.1 ± 50.3 min, p = 0.613). Regarding the caregivers, in 2020, wake-up times (2019: 6:46 ± 0:50 am vs. 2020: 6:39 ± 0:50 am, p = 0.017) and bedtimes (22:53 ± 1:17 pm vs. 22:42 ± 1:04 pm, p = 0.016) became significantly earlier compared to 2019. Among infants staying at home, total sleep time and percentage of outdoor play decreased significantly, and media use increased significantly in 2020. Lower levels of exercise and more frequent media viewing may have caused prolonged sleep latency in these children. The percentage of caregivers responding with "negative childcare feelings" was significantly higher in the group with less than three nursery school attendance days. Caregivers and infants staying at home are a high-risk group during the pandemic.

Developmental Profile of Sleep and Its Potential Impact on Daytime Functioning from Childhood to Adulthood in Sickle Cell Anaemia

Young individuals with sickle cell anaemia (SCA) experience sleep disturbances and often experience daytime tiredness, which in turn may impact on their daytime functioning and academic attainment, but there are few longitudinal data.

METHODS

Data on sleep habits and behaviour were taken on the same day as an in-hospital polysomnography. This study assesses the developmental sleep profiles of children and young adults aged 4-23 years old with SCA. We examined retrospective polysomnography (PSG) and questionnaire data.

RESULTS

A total of 256 children with a median age of 10.67 years (130 male) were recruited and 179 returned for PSG 1.80-6.72 years later. Later bedtimes and a decrease in total sleep time (TST) were observed. Sleep disturbances, e.g., parasomnias and night waking, were highest in preschool children and young adults at their first visit. Participants with lower sleep quality, more movement during the night and increased night waking experienced daytime sleepiness, potentially an indicator of lower daytime functioning. Factors influencing sleep quantity included age, hydroxyurea prescription, mean overnight oxygen saturation, sleep onset latency, periodic limb movement, socioeconomic status and night waking.

CONCLUSION

Sleep serves an important role for daytime functioning in SCA; hence, quantitative (i.e., PSG for clinical symptoms, e.g., sleep-disordered breathing, nocturnal limb movement) and qualitative (i.e., questionnaires for habitual sleep behaviour) assessments of sleep should be mutually considered to guide interventions.

Association between objectively assessed physical activity and sleep quality in adolescence. Results from the GINIplus and LISA studies

STUDY OBJECTIVES

Population-based studies on the association of objectively assessed physical activity (PA) with sleep among adolescents are rare. We examined this association by applying accelerometry and accounting for the day-by-day variability.

METHODS

Accelerometers (Actigraph GT3X) were worn for one week by 1223 participants during the 15-year follow-up of the German birth cohorts (German infant study on the Influence of Nutrition Intervention plus air pollution and genetics on allergy development, GINIplus) and (Influence of Lifestyle factors on the development of the Immune System and Allergies in East and West Germany, LISA) to measure PA and sleep. PA was categorised into sedentary, lifestyle and moderate-to-vigorous physical activity (MVPA) referring to Sasaki and Romanzini. Sleep was analysed according to the algorithm developed by Sadeh. Sleep quality was represented by sleep efficiency (SE), sleep onset latency (SOL) and time awake per hour after sleep onset (TAPH). Sleep and activity were additionally reported by diaries. Linear and generalized mixed-effects-models with logit-link with subject specific random intercepts were used stratified by sex and adjusted for confounding variables.

RESULTS

Physical activity appears to be associated only with sleep quality the following night. Among female participants, SE improved (β = 0.12 [95% CI = (0.05; 0.18)]) per 10 minutes increase of MVPA. SOL decreased (OR = 0.83 [95% CI = (0.69; 0.99)]) among male participants with at least 60 min of MVPA per day. Engaging in leisure sport MVPA was associated with higher SE among female (β = 0.70 [95% CI = (0.22; 1.17)]) and male participants (β = 0.76 [95% CI = (0.18; 1.34)]). Also, TAPH among female (β = -0.37 [95% CI = (-0.65; -0.09)]) and SOL among male subjects (OR = 0.70 [95% CI = (0.57; 0.85)]) decreased. Increasing lifestyle activity was related to longer SOL among female (OR = 1.36 [95% CI = (1.15; 1.62)]) and male subjects (OR = 1.32 [95% CI = (1.10; 1.58)]).

CONCLUSIONS

In this large population-based sample of German adolescents MVPA and leisure sport improved short term sleep quality, supporting regular PA in adolescents for their health benefit.

Associations between objective measures of physical activity, sleep and stress levels among preschool children

Background

Cortisol is often used as a biological marker for stress. When measured in urine or serum, representing a short-term measurement of the hormone, it has been associated with unfavorable sleep characteristics and both low and high physical activity levels. However, cortisol in hair represents a long-term stress measure and has been suggested as a promising new marker for chronic stress. Therefore, we aimed to examine the association between objectively measured sleep, physical activity and hair cortisol levels in preschool children.

Methods

In order to obtain objective measures of physical activity and sleep habits, 54 children aged 2–6 years wore an ActiGraph for 5 consecutive days and nights. For chronic stress measurements of each child, hair was cut from the back of the head close to the scalp for analysis of cortisol levels. Associations between measured sleep quality and quantity and level of physical activity and hair cortisol levels were estimated using linear regression analysis, presented as β. Results were adjusted for sex, age and BMI z-score.

Results

We found no significant association between log-transformed cortisol (pg/mg) and sleep duration (hours) (β = − 0.0016, p = 0.99), sleep efficiency (β = − 3.1, p = 0.18), sleep latency (β = 0.015, p = 0.16) or physical activity level (100 counts per min) (β = 0.014, p = 0.22). However, sleep latency (min) was directly associated with physical activity (counts per min) levels (β = 35.2, p = 0.02), while sleep duration (hours) (β = − 142.1, p = 0.55) and sleep efficiency (%) (β = − 4087, p = 0.26) showed no significant associations.

Conclusions

In our study, a high physical activity level was associated with poorer sleep habits. Neither sleep quality nor physical activity were related to long term cortisol exposure. These results are among the first to study associations between objectively measured sleep, physical activity and chronic cortisol levels among preschool children. More and larger studies are therefore needed.

Association of Sunlight Exposure with Sleep Hours in Iranian Children and Adolescents: The CASPIAN-V Study

We aimed to assess the association of sunlight exposure with sleep duration and sleep onset time in children. Data were obtained from the fifth survey of a national school-based surveillance program in Iran. Sunlight exposure time, sleep duration, sleep onset time, physical activity time, mental health status and frequency of consuming coffee and tea were recorded. Overall, 14 274 students aged 7-18 years were recruited. Sleep duration was associated positively with sex, age, body mass index and physical activity, as well as with sunlight exposure and negatively with the consumption of coffee and tea. Higher physical activity, exposure to sunlight and mental status score in children exposed to sunlight via their face, hands, arms and feet, reduced the likelihood of sleep onset time after midnight (odds ratio (OR) = 0.909, 0.741 and 0.554 respectively). Daily exposure to sunlight may increase sleep duration and advance the sleep onset time in children and adolescents.

Bidirectional Associations between Objective Physical Activity and Sleep Patterns in Spanish School Children

Physical activity (PA) and sleep contribute to better children’s health. Nonetheless, the bidirectional relationship between both of these health-related factors is unclear when using objective measures. The aims of this study were (1) to describe the PA (light PA and moderate-to-vigorous PA (MVPA) and sleep (duration, latency, and efficiency) patterns of children and compare them with recommendations, and (2) to analyze the bidirectional association between PA levels and sleep patterns in 470 Spanish children according to sex (average age of 8.4 (0.4) years, 51.9% boys). A tri-axial accelerometer and sleep logs were used to measure PA (light PA and MVPA) and sleep patterns (duration, latency, and efficiency) in the children for seven consecutive days. Linear mixed models were conducted to analyze the bidirectional association (PA → sleep and sleep → PA) adjusted for the child, the sex, the school, and the day of observation. The results showed that, overall, the children did not meet the sleep duration recommendations per day. Regarding the bidirectional association, increased light PA and MVPA during the day was related to decreased sleep duration but an improvement in sleep efficiency that night. However, sleep duration and sleep efficiency were only related negatively and positively to light PA the following day, respectively. Regarding sex, light PA was associated with decreased sleep duration in both sexes, although the average value was lower in boys. In addition, light PA was also related only to an improvement in sleep efficiency the same night in both sexes, with girls generally having more efficient sleep. More studies in a representative sample of children that use objective measures to corroborate these results are needed.

The effect of mild sleep deprivation on diet and eating behaviour in children: protocol for the Daily Rest, Eating, and Activity Monitoring (DREAM) randomized cross-over trial

BACKGROUND

Although insufficient sleep has emerged as a strong, independent risk factor for obesity in children, the mechanisms by which insufficient sleep leads to weight gain are uncertain. Observational research suggests that being tired influences what children eat more than how active they are, but only experimental research can determine causality. Few experimental studies have been undertaken to determine how reductions in sleep duration might affect indices of energy balance in children including food choice, appetite regulation, and sedentary time. The primary aim of this study is to objectively determine whether mild sleep deprivation increases energy intake in the absence of hunger.

METHODS

The Daily, Rest, Eating, and Activity Monitoring (DREAM) study is a randomized controlled trial investigating how mild sleep deprivation influences eating behaviour and activity patterns in children using a counterbalanced, cross-over design. One hundred and ten children aged 8-12 years, with normal reported sleep duration of 8-11 h per night will undergo 2 weeks of sleep manipulation; seven nights of sleep restriction by going to bed 1 hr later than usual, and seven nights of sleep extension going to bed 1 hr earlier than usual, separated by a washout week. During each experimental week, 24-h movement behaviours (sleep, physical activity, sedentary behaviour) will be measured via actigraphy; dietary intake and context of eating by multiple 24-h recalls and wearable camera images; and eating behaviours via objective and subjective methods. At the end of each experimental week a feeding experiment will determine energy intake from eating in the absence of hunger. Differences between sleep conditions will be determined to estimate the effects of reducing sleep duration by 1-2 h per night.

DISCUSSION

Determining how insufficient sleep predisposes children to weight gain should provide much-needed information for improving interventions for the effective prevention of obesity, thereby decreasing long-term morbidity and healthcare burden.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12618001671257 . Registered 10 October 2018.

Physical activity and objectively assessed sleep in 6-month-old infants in Taiwan

Adequate physical activity is associated with improved sleep in adults. Such associations, however, vary greatly across studies in pediatric populations, with no studies involving infants found in the literature. This prospective observational study was designed, therefore, to examine the association between physical activity and sleep patterns in infants. A total of 183 healthy infants aged 6 months wore an actigraph for 7 days to measure physical activity and sleep. Parents and caregivers completed a sleep-activity diary over the same period documenting the different types of infant activities. Daily mean time spent in screen-time-or-limited physical activity, including screen-based (e.g., watching television or other electronic devices) and non-screen based activity (e.g., quiet play or restricted infant movement when carried by caregivers or seated in high chairs, swings, or bouncer seats), was 6.68 hr (SD = 1.99), which represented 47.50% of daytime waking hours (SD = 13.73). We found that 65 (35.5%) infants engaged in some screen time during the study, with 10 (5.5%) infants having an average daily screen time >30 min. In our multivariate linear regression model, more hours of screen-time-or-limited physical activity per day were significantly associated with a decrease in total daily 24 hr sleep duration (p < 0.01). Findings from our study suggest that reducing screen-time-or-limited physical activity might be an approach for promoting adequate sleep and lengthening infant daily sleep duration.

Temporal and bi-directional associations between sleep duration and physical activity/sedentary time in children: An international comparison

The purpose of this multinational and cross-sectional study was to investigate whether nighttime sleep duration was associated with physical activity (PA) and sedentary time (SED) the following day, whether daytime PA/SED were associated with sleep duration the subsequent night, and whether the associations were modified by sex and study sites. Data from 5779 children aged 9-11years were analyzed. A waist-worn Actigraph GT3X+ accelerometer was used to assess children's 24-h movement behaviours for 7days, i.e. sleep duration, total SED, light-intensity physical activity (LPA), and moderate- to vigorous-intensity physical activity (MVPA). Multilevel linear regression models were used to account for the repeated measures nested within participants (there were up to 7 sleep→PA/SED and PA/SED→sleep pairings per participant) and schools, and adjusted for covariates. To facilitate interpretation, all sleep and PA/SED variables were standardized. Results showed that the relationship between sleep and PA/SED is bi-directional in this international sample of children. Specifically, for each one standard deviation (SD) unit increase in sleep duration, SED the following day decreased by 0.04 SD units, while LPA and MVPA increased by 0.04 and 0.02 SD units, respectively. Sleep duration decreased by 0.02 SD units and increased by 0.04 SD units for each one SD unit increase in SED and MVPA, respectively. Sleep duration was not affected by changes in LPA. These associations differed across sex and study sites in both directions. However, since the observed effect sizes are subtle, public health initiatives should consider the clinical and practical relevance of these findings.

Bi-directional association between sleep and outdoor active play among 10-13 year olds

BACKGROUND

The purpose of this study was to investigate whether there is a bi-directional relationship between sleep characteristics (time in bed, sleep duration, sleep chronology, and sleep efficiency) and time spent participating in outdoor active play among children.

METHODS

Participants consisted of 433 children aged 10-13 years from Kingston, ON, Canada. Time in bed, sleep duration, sleep chronology, and sleep efficiency were measured for 8 consecutive nights using data from a sleep log and Actical accelerometer. Outdoor active play was measured for the 7 days that fell in between these 8 nights using a combination of data from accelerometers, global positioning system loggers, and geographic information systems. Generalized estimating equation models were used to assess the relationships between sleep characteristics and outdoor active play. These models accounted for the repeated measures nested within participants and adjusted for several confounders (e.g., age, sex, family income, neighborhood traffic and green space).

RESULTS

Time in bed, sleep duration, sleep chronology, and sleep efficiency were not significantly associated with the following day's outdoor active play. There was a significant (p = 0.017) association between outdoor active play and the following night's time in bed, which suggested that each hour increase in outdoor active play was associated with a 4.0 min increase in time in bed. Outdoor active play was not significantly associated with sleep duration, sleep chronology, or sleep efficiency.

CONCLUSIONS

None of the sleep characteristics predicted the following day's outdoor active play. Increase time spent in outdoor active play predicted a longer time in bed, but not sleep duration, sleep chronology, or sleep efficiency.

Relationship between parent knowledge of child sleep, and child sleep practices and problems: A pilot study in a children's hospital cohort

AIM

To describe parent reports of sleep practices, and examine associations with parent knowledge of child sleep, and whether children's sleep practices differ between parents who underestimated, overestimated or accurately estimated children's sleep needs.

METHODS

Parents of children aged 2-12 years (n = 115) attending hospital inpatient or day wards were approached and asked to report child sleep routines, sleep problems, parent education, household income and parent knowledge of child sleep via questionnaire.

RESULTS

Younger age was associated with earlier bedtimes and wake times, shorter sleep latencies, longer sleep durations and greater sleep problems (P < 0.05). Parents from higher income homes reported earlier bedtimes and wake times, shorter sleep latencies and fewer sleep problems (P < 0.05). Parents with higher education reported shorter sleep latencies (P < 0.05). Parents with greater knowledge about child sleep reported earlier weekday and weekend bedtimes (r _s  ≥ 0.26) and wake times (r _s  ≥ 0.21) and greater consistency between their child's weekend and weekday sleep routines (P < 0.05). In comparison with parents who correctly estimated their child's sleep needs: parents who underestimated reported later weekday bedtimes (on average, 46 min), and longer sleep latencies (17 min); parents who overestimated reported longer sleep latencies (22 min). These findings remained significant when controlling for child age (P < 0.05).

CONCLUSION

Parents with increased sleep knowledge, higher incomes and higher levels of education were more likely to report earlier bedtimes, wake times and more consistent sleep routines for their children.

Sleep differences in one-year-old children were related to obesity risks based on their parents' weight according to baseline longitudinal study data

AIM

Parental obesity is the predominant risk factor for child obesity. We compared sleep in one-year-old children with different obesity risks, based on parental weight, and explored associations with weight, parental sleep and family factors.

METHODS

Baseline data from 167 families participating in a longitudinal obesity prevention programme was used. Sleep patterns were compared between groups with high and low obesity risks, based on parental weight, and associations between child sleep and weight status, family obesity risk and parental sleep were explored. Sleep was assessed using child sleep diaries and standard parental questionnaires.

RESULTS

Later bedtime, longer sleep onset latency and lower sleep efficiency were observed among children in the high-risk group. Child sleep onset latency was associated with the family obesity risk (β = 0.25, p = 0.001), child bedtime with both maternal (β = 0.33, p < 0.01) and paternal bedtime (β = 0.22, p < 0.05) and child sleep efficiency with maternal sleep quality (β = 0.20, p < 0.01). The child's bedtime was weakly associated with their body mass index (β = 0.17, p < 0.05).

CONCLUSION

Sleep differed between one-year-old children with high or low obesity risks, based on their parents' body mass index, and was associated with the family obesity risk and parental sleep. The child's bedtime was weakly associated with their weight status.

Genetic variants in RBFOX3 are associated with sleep latency

Time to fall asleep (sleep latency) is a major determinant of sleep quality. Chronic, long sleep latency is a major characteristic of sleep-onset insomnia and/or delayed sleep phase syndrome. In this study we aimed to discover common polymorphisms that contribute to the genetics of sleep latency. We performed a meta-analysis of genome-wide association studies (GWAS) including 2 572 737 single nucleotide polymorphisms (SNPs) established in seven European cohorts including 4242 individuals. We found a cluster of three highly correlated variants (rs9900428, rs9907432 and rs7211029) in the RNA-binding protein fox-1 homolog 3 gene (RBFOX3) associated with sleep latency (P-values=5.77 × 10(-08), 6.59 × 10(-)(08) and 9.17 × 10(-)(08)). These SNPs were replicated in up to 12 independent populations including 30 377 individuals (P-values=1.5 × 10(-)(02), 7.0 × 10(-)(03) and 2.5 × 10(-)(03); combined meta-analysis P-values=5.5 × 10(-07), 5.4 × 10(-07) and 1.0 × 10(-07)). A functional prediction of RBFOX3 based on co-expression with other genes shows that this gene is predominantly expressed in brain (P-value=1.4 × 10(-316)) and the central nervous system (P-value=7.5 × 10(-)(321)). The predicted function of RBFOX3 based on co-expression analysis with other genes shows that this gene is significantly involved in the release cycle of neurotransmitters including gamma-aminobutyric acid and various monoamines (P-values<2.9 × 10(-11)) that are crucial in triggering the onset of sleep. To conclude, in this first large-scale GWAS of sleep latency we report a novel association of variants in RBFOX3 gene. Further, a functional prediction of RBFOX3 supports the involvement of RBFOX3 with sleep latency.

Racial/Ethnic and Socio-Contextual Correlates of Chronic Sleep Curtailment in Childhood

STUDY OBJECTIVES

To examine the association between race/ethnicity and sleep curtailment from infancy to mid-childhood, and to determine the extent to which socioeconomic and contextual factors both explain racial/ethnic differences and are independently associated with sleep curtailment.

METHODS

We studied 1,288 children longitudinally in Project Viva, a pre-birth cohort study, from 6 months to 7 years of age. The main exposure was the child's race/ethnicity. The main outcome was a sleep curtailment score from 6 months to 7 years. The score ranged from 0-13, where 0 indicated maximal sleep curtailment and 13 indicated never having curtailed sleep.

RESULTS

The mean (standard deviation) sleep curtailment score was 10.2 (2.7) points. In adjusted models (β [95% CI]), black (-1.92, [-2.39, -1.45] points), Hispanic (-1.58, [-2.43, -0.72] points), and Asian (-1.71, [-2.55, -0.86] points) children had lower sleep scores than white children. Adjustment for sociodemographic covariates attenuated racial/ethnic differences in sleep scores for black (by 24%) and Hispanic children (by 32%) but strengthened the differences for Asian children by 14%. Further adjustment for environmental and behavioral variables did not substantially change these differences. Independently, low maternal education, living in households with incomes < $70,000, viewing more TV, and having a TV in the child's bedroom were associated with lower sleep scores.

CONCLUSIONS

Chronic sleep curtailment from infancy to mid-childhood was more prevalent among black, Hispanic, and Asian children. These differences were partially but not entirely explained by socio-contextual variables. Independently, children from lower socioeconomic status and those with greater exposures to TV also had greater sleep curtailment.

Associations of outdoor play and screen time with nocturnal sleep duration and pattern among young children

AIM

Sleep duration and pattern have important implications for children's health. This study aims to investigate nocturnal sleep duration, sleep pattern and their relationships with outdoor play and screen time among children aged 2 to five years.

METHODS

The study used data from the Healthy Beginnings Trial undertaken in Sydney, Australia. Data on children's sleep, outdoor playtime and screen time were reported by mothers via face-to-face interviews when children were 2, 3.5 and five years old. Both cross-sectional and longitudinal analyses were conducted.

RESULTS

At age 2, 3.5 and five years, 497, 415 and 369 mother-child dyads participated. Significantly, there was an overall increase in children's nocturnal sleep duration, sleep latency and an earlier bedtime, and there was a decrease in the proportion of children who woke at night over time. Each additional hour of screen time was associated with three-minute (95% CI 0.6-5) shorter sleep, 1.6-minute (95% CI 0.59-2.63) longer sleep latency, four-minute (95% CI 1.8-6.0) later bedtime and less likely sleeping ≥10 hours per night with adjusted odds ratio 0.88 (95% CI 0.77-1.00), after controlling for mothers' demographics.

CONCLUSION

Among young children, screen time and outdoor playtime were associated with sleep duration and pattern. Reducing screen time and increasing outdoor playtime might help improving children's sleep.

Daytime physical activity and sleep in pre-schoolers with developmental disorders

AIM

This study aims to investigate the association between daytime physical activity (PA) and sleep in pre-schoolers with or without autism spectrum disorders (ASDs).

METHOD

Thirty-one pre-school children with ASD and 16 age-matched controls were recruited. Sleep and PA patterns were measured with an Actiwatch for 7 days. After average PA values were calculated for three periods (morning, afternoon and evening) of each day for each child, the days with maximum (active) and minimum (inactive) PA values for these three periods were determined. The Wilcoxon signed-rank test was used to compare sleep following active mornings, afternoons and evenings with that following inactive time periods.

RESULTS

In control children, sleep onset time following active mornings/afternoons did not differ from that following inactive mornings/afternoons. In contrast, sleep onset following the most inactive morning (median sleep onset time: 9:57 pm) and the most inactive afternoon (median sleep onset time: 10:24 pm) began significantly later than that following the most active mornings (median sleep onset time: 9:21 pm) and the most active afternoons (median sleep onset time: 9:39 pm) in children with ASD. The percentage of sleep for control children following active mornings was significantly higher (median: 93.2%) than that following inactive ones (median: 91.7%). Significant associations were not found between evening PA and sleep in either ASD or control children.

CONCLUSIONS

A high level of morning and afternoon PA can advance the sleep phase in children with ASD.

Sleep, physical activity and BMI in six to ten-year-old children measured by accelerometry: a cross-sectional study

Background

The aim of this study is to describe the relationship between objective measures of sleep, physical activity and BMI in Swedish pre-adolescents. The day-to-day association between physical activity and sleep quality as well as week-day and weekend pattern of sleep is also described.

Method

We conducted a cross sectional study consisted of a cohort of 1.231 children aged six to ten years within the Stockholm county area. Sleep and physical activity were measured by accelerometry during seven consecutive days. Outcome measures are total sleep time, sleep efficiency, sleep start and sleep end; physical activity intensity divided into: sedentary (<1.5 METS), light (1.5 to 3 METS) and moderate-to-vigorous (> 3 METS); and Body Mass Index standard deviations score, BMIsds.

Results

Total sleep time decreased with increasing age, and was shorter in boys than girls on both weekdays and weekends. Late bedtime but consistent wake-up time during weekends made total sleep time shorter on weekends than on weekdays. Day-to-day within-subject analysis revealed that moderate-to-vigorous intense physical activity promoted an increased sleep efficiency the following night (CI < 0.001 to 0.047), while total sleep time was not affected (CI -0.003 to 0.043). Neither sleep duration (CI -0.024 to 0.022) nor sleep efficiency (CI -0.019 to 0.028) affected mean physical activity level the subsequent day. The between-subject analysis indicates that the sleep of children characterized by high moderate-to-vigorous physical activity during the day was frequently interrupted (SE = -.23, P < .01). A negative association between BMIsds and sleep duration was found (-.10, p < .01).

Conclusions

Short sleep duration was associated with high BMI in six to ten year old children. This study underscores the importance of consistent bedtimes throughout the week for promoting sleep duration in preadolescents. Furthermore, this study suggests that a large proportion of intensive physical activity during the day might promote good sleep quality.

Relationships of objectively measured physical activity and sleep with BMI and academic outcomes in 8-year-old children

Current guidelines in place for sleep and physical activity in childhood are the result of data collected in the form of self-reports. Exact measurement of activity dimensions and sleep characteristics are essential. The purpose of clearly established parameters is for the intent of verifying health outcomes and evaluating interventions. The purpose of this research was to determine the relationships between the objective dimensions of physical activity, sleep, weight status, academic achievement, and academic behavior. This cross-sectional correlational descriptive design examined the activity and sleep patterns continuously for 24 hours/7 days with triaxial accelerometers in a low income African American sample of 8-year-olds. A qualitative component gathered additional identifiers. This sample was overweight/obese, inactive, and sleep-deprived. Moderate-vigorous activity was correlated with reading scores. Confirmed in this research was the association between sleep duration, physical activity intensities, and academics. Positive health outcomes in children are endorsed by an energy balance.

Maintaining recommended sleep throughout the week is associated with increased physical activity in children

OBJECTIVE

Given evidence of weekday-weekend variability in children's sleep and associations with obesity there is rationale for exploring sleep in relation to weekday and weekend physical activity (PA) and examining whether weekday-weekend variations in sleep impact physical activity.

METHODS

Children's (n=856) physical activity was measured using accelerometry (Toronto; 2010-2011). Sleep was assessed via parental report and collapsed into three categories (<9h; 9-10h; ≥ 10 h) and differences in anthropometric and physical activity characteristics were assessed. Data were compared to determine whether sleep increased, decreased or was maintained across the week and relationships with activity and overweight/obesity were explored (cross-sectional analysis) after controlling for confounders.

RESULTS

On weekdays, children who slept the least (<9h) were less active in terms of overall intensity than those attaining ≥ 10 h, and more were overweight/obese (p<0.05). On weekends, differences in light physical activity occurred at lower sleep levels. Weekday-weekend sleep regularity mattered; overall intensity was higher among those maintaining recommended sleep (>9h) compared to those engaging in weekend-catch-up-sleep.

CONCLUSION

While sleep is associated with obesity and activity in children, relationships vary by day. Recommended weekday-weekend sleep (regularity) supports healthy activity and should be an important health-promoting strategy. Future studies using longitudinal designs (to establish causality) are recommended.

The Healthy Start project: a randomized, controlled intervention to prevent overweight among normal weight, preschool children at high risk of future overweight

BACKGROUND

Research shows that obesity prevention has to start early. Targeting interventions towards subgroups of individuals who are predisposed, but yet normal weight, may prove more effective in preventing overweight than interventions towards unselected normal weight subsets. Finally, interventions focused on other factors than diet and activity are lacking. The objectives were to perform a randomized, controlled intervention aiming at preventing overweight in children aged 2-6 years, who are yet normal weight, but have high predisposition for future overweight, and to intervene not only by improving diet and physical activity, but also reduce stress and improve sleep quality and quantity.

METHODS/DESIGN

Based on information from the Danish National Birth Registry and administrative birth forms, children were selected based on having either a high birth weight, a mother who was overweight prior to pregnancy, or a familial low socioeconomic status. Selected children (n = 5,902) were randomized into three groups; an intervention group, a shadow control group followed in registers exclusively, and a control group examined at the beginning and at the end of the intervention. Approximately 21% agreed to participate. Children who presented as overweight prior to the intervention were excluded from this study (n = 92). In the intervention group, 271 children were included, and in the control group 272 were included. Information obtained from the shadow control group is on-going, but it is estimated that 394 children will be included. The intervention took place over on average 1½ year between 2009 and 2011, and consisted of optional individual guidance in optimizing diet and physical activity habits, reducing chronic stress and stressful events and improving sleep quality and quantity. The intervention also included participation in cooking classes and play arrangements. Information on dietary intake, meal habits, physical activity, sleep habits, and overall stress level was obtained by 4-7 day questionnaire diaries and objective measurements.

DISCUSSION

If the Healthy Start project is effective in preventing excessive weight gain, it will provide valuable information on new determinants of obesity which should be considered in future interventions, and on new strategies to prevent development of overweight and obesity at an early age.

Increased sleep latency and reduced sleep duration in children with asthma

STUDY OBJECTIVE

Sleep disturbance is reported to be more prevalent in children and adolescents with asthma than those without. However, this has not been described adequately using objective measures. The aim of this study was to objectively characterise sleep disturbance in asthmatic and non-asthmatic children and adolescents.

METHODS

A retrospective analysis of polysomnography recordings from children aged 5-17 years old, with (n = 113) and without asthma (n = 104), referred for a sleep study over the period 2005-2010 at the Paediatric Sleep Unit, John Hunter Children's Hospital in Newcastle, NSW Australia, was carried out.

RESULTS

Polysomnographic recordings were analysed to compare sleep quality and quantity between asthmatic and non-asthmatic children. Sleep latency was significantly longer in asthmatic children compared to controls. However, this result was significant for females only (46.2 (5.6) vs 33.2 (2.7) min, p < 0.05). Male asthmatics had significantly shorter sleep duration (425.9 (5.4) vs 441.8 (5.4) min, p < 0.05) than male controls.

CONCLUSIONS

Sleep disturbance exists in children with asthma and manifests differently in males and females. Further investigation into the clinical implication of increased sleep latency and reduced sleep duration upon daytime functioning and lifestyle behaviours in children and adolescents with asthma is warranted.

Sleep characteristics of young children in Japan: internet study and comparison with other Asian countries

BACKGROUND

A recent international Internet-based study of young children (birth to 36 months) found that total sleep duration in Japan was the shortest among 17 countries/regions. The present study compared features of children's sleep in Japan relative to those in other Asian countries/regions.

METHODS

Parents of 872 infants and toddlers in Japan (48.6% boys), and parents of 20 455 infants and toddlers in 11 other Asian countries/regions (48.1% boys; China, Hong Kong, India, Indonesia, Korea, Malaysia, Philippines, Singapore, Taiwan, Thailand, and Vietnam) completed an Internet-based expanded version of the Brief Infant Sleep Questionnaire.

RESULTS

Young children in Japan exhibited significantly fewer nocturnal wakings and shorter daytime sleep in comparison with other Asian countries/regions. Although the former finding was apparent in all age groups, the reduced duration of daytime sleep in Japan was not present until after 3 months of age. Interestingly, sleep problems were reported by significantly fewer parents in Japan compared with those in other Asian countries/regions, although parents in Japan reported significantly more difficulty at bedtime.

CONCLUSIONS

The short sleep duration of young children in Japan is largely due to a relatively short duration of daytime sleep. Significant differences in sleep characteristics in Japan relative to other Asian regions were found primarily after 3 months of age. Future studies should further explore the underlying causes and the potential impacts of these sleep differences.

Temporal associations between daytime physical activity and sleep in children

OBJECTIVES

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

STUDY DESIGN

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

RESULTS

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

CONCLUSIONS

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