Predictors of shorter sleep in early childhood

ObjectiveThe aim of this study was to identify socio-demographic and home environmental predictors of shorter sleep in early childhood, and to examine whether effects were mediated by the timing of bedtime or wake time.MethodsParticipants were from Gemini, a British birth cohort of twins, and included 1702 children; one randomly selected from each twin pair. Parents reported night-time sleep duration at an average age of 15.8 months (range 14–27 months) using a modified version of the Brief Infant Sleep Questionnaire. Multiple logistic regression models were used to identify predictors of shorter sleep for this study.ResultsUsing a cut-off of <11 h a night, shorter sleep was reported in 14.1% of children. Lower maternal education, non-white ethnic background, being male, low birth weight, living in a home with >1 older child and watching >1 h of TV in the evening were independently associated with shorter sleep. Mediation analyses showed that associations between education, ethnicity, evening TV viewing and sleep were driven predominantly by later bedtimes, while sex differences were driven predominantly by earlier wake times in boys.ConclusionIn this sample, multiple environmental factors were associated with shorter sleep in young children, with several operating predominantly through later bedtime. An emphasis on the importance of an early and consistent bedtime could help promote healthy sleep and reduce inequalities in child health.     

Sleep patterns and their age-related changes in elementary-school children

ObjectivesThis study aimed to evaluate children’s bedtime, wake-up time, total sleep duration (TSD), sleep latency, and daytime napping by age and gender. Its secondary aim was to compare sleep duration among demographic and lifestyle factors.MethodsWe performed a cross-sectional study of 3639 children in Daegu, Korea, comparing bedtimes, wake-up times, TSDs, daytime naps, and sleep latency according to age and gender, as well as comparing sleep duration according to the children’s demographic and lifestyle factors.ResultsBedtime and TSD varied significantly by age. But wake-up time differences were not as large, as the differences in bedtimes and TSDs. There were no gender differences in any sleep parameters. The percentage of the children who took naps decreased until age 9 and began increasing again at age 10. Children who lived in apartments got less sleep than did those living in other types of housing. Extracurricular academic activities, duration and timing of television-watching, and computer playing were also related to the children’s sleep duration.ConclusionsOlder children sleep less than younger children; the main reason is late bedtimes. Late bedtimes may be due to socio-cultural factors, high levels of nighttime and recreational activities, and/or excessive academic activities.     

Sleep-related movement disorders and growing pains: differences in daytime and bedtime behavior in 2–6 year old children with cleft palate

BackgroundBehavioural difficulties are common in children with sleep disorders. However, up to now no study has investigated the association between sleep-related movement disorders (SRMD) and behavior in children with craniofacial cleft. The aim of this study was to assess the frequency and impact of SRMD and growing pains in daytime/bedtime behavior in young children with cleft palate.MethodsCross-sectional survey study of sleep and behavior in 2.0–6.9 year old children with cleft palate. Parents completed the Pediatric Sleep Questionnaire, which queries reports of periodic limb movements (PLMS), restless leg syndrome (RLS), growing pains, daytime sleepiness, sleep latency/duration, and the Conners' Early Childhood Questionnaire which asks about behavioral difficulties.ResultsAmong 71 children with cleft palate (52.1% boys) 14.1 % screened positive for PLMS, 8.5% reported RLS and 9.9% growing pains. Children who screened positive for PLMS and RLS were more likely to report sleepiness (PLMS 40% vs. 4.9%, p = 0.001; RLS 33.3% vs. 7.7%, p = 0.04) and long sleep latency (PLMS 80% vs. 32.8%, p = 0.005; RLS 100% vs. 33.8%, p = 0.002) compared to those who did not endorse the respective sleep problems. Children who reported PLMS had a higher T-score for emotional (58.2 ± 7.6 vs. 50.7 ± 8.4, p = 0.01) and somatic symptoms (66.2 ± 15.2 vs. 49.9 ± 9.5, p = 0.0001). Sleepiness was associated to an increased frequency of externalizing, psychiatric and somatic problems. While children with long sleep latency reported more emotional and somatic symptoms, and those with reduced sleep duration more internalizing difficulties.ConclusionsParents of young children with cleft palate reported frequently PLMS, RLS and growing pains. Daytime/bedtime behavior varies depending on the presence of SRMD. Sleepiness and sleep variables might play a role on behavioural problems in children with cleft and SRMD symptoms.     

Effects of sleep duration and weekend catch-up sleep on falling injury in adolescents: a population-based study

ObjectiveThis population-based study aimed to determine the effects of sleep deprivation and compensatory weekend catch-up sleep on the risk of falls in adolescents.MethodsData from the 2013 Korean Youth Risk Behavior Web-based Survey on 57,225 adolescents were investigated. Demographic, socioeconomic, sleep-related, health-related behavioral, and psychological variables were compared between fallers (n = 7346) and non-fallers (n = 49,879). Multivariate logistic regression analysis using a hierarchical model was carried out to identify sleep-related factors (eg, sleep duration, longer weekend catch-up sleep) independently contributing to the risk of falls.ResultsCompared to non-fallers, fallers were associated with a shorter sleep duration (p = 0.001) and later bedtimes on weekdays and weekends (p < 0.001). An average sleep duration of ≤ 5 h (odds ratio [OR] 1.23, 95% confidence interval [CI] 1.12–1.34) and of 6 h (OR 1.12, CI 1.03–1.21) were associated with an increased risk of falls. By contrast, an average sleep duration of ≥ 9 h (OR 0.90, CI: 0.82–0.99) and longer weekend catch-up sleep (OR 0.94, CI: 0.89–0.99) were associated with a decreased risk of falls.ConclusionOur results corroborate previous suggestions that short sleep duration is a major risk factor for falls among adolescents. Moreover, our study provided a novel finding that longer sleep duration and longer weekend catch-up sleep may have a protective effect against falls. Our findings have important public health implications that modifying school schedules to increase sleep duration could reduce unintentional falls and injuries in school-aged adolescents.     

Later bedtime is associated with angina pectoris in middle-aged and older adults: results from the Sleep Heart Health Study

ObjectivesSleep timing is related to several risk factors for angina pectoris (AP), such as obesity and diabetes. This study was designed to evaluate the relationship between sleep timing and AP, specifically whether later bedtime was associated with AP in middle-aged and older adults.MethodsThis community-based study was based on the Sleep Heart Health Study cohort and included 4710 participants (45.9% men, aged 63.3 ± 11.0 years). Lifestyle and epidemiological information were obtained from baseline records. Self-reported sleep measures provided information on bedtime and wake-up time of weekdays and weekends. Individuals were divided into three categories according to bedtime (≤22:00, 22:01–23:00, and >23:00). Odds ratios (OR) and 95% confidence intervals (CIs) of AP for bedtimes were estimated with multivariate logistic regression analysis.ResultsThe prevalence of AP was 44.2% and the distribution of weekday bedtimes ≤22:00, 22:01–23:00_, and >23:00 were 36.6%, 47.5% and 46.0%, respectively. After adjusting for potential confounders, weekday bedtimes >23:00 (OR 1.34; 95% CI 1.13–1.60; P = 0.001) and 22:01–23:00 (OR 1.54; 95% CI 1.29–1.82; P < 0.001) were significantly associated with an increased risk of AP compared with the reference group (≤22:00). In addition, weekend bedtimes >23:00 (OR 1.44; 95% CI 1.20–1.73; P < 0.001) and 22:01–23:00 (OR 1.70; 95% CI 1.40–2.05; P < 0.001) increased the risk of AP.ConclusionsLater bedtimes on both weekdays and weekends were significantly associated with an increased prevalence of AP. Early bedtimes may help people decrease the risk of AP.     

Sleep duration and timing are nonlinearly associated with depressive symptoms among older adults

BackgroundGeriatric depression is a common but preventable psychiatric disorder; however, its association with specific sleep patterns remains unclear. Therefore, we examined the association of self-reported sleep duration and sleep timing with depressive symptoms in the older population.MethodsA total of 1068 older Taiwanese adults (52.7% women; 72.2 ± 5.7 y) responded to a telephone survey during 2019–2020. Self-reported data on sociodemographic characteristics, sleep duration, bedtime, wake-up time (adapted items from Pittsburgh Sleep Quality Index), and depressive symptoms (five-item Center for Epidemiological Studies–Depression scale) were included. Generalized additive models were used to examine the nonlinear associations of sleep duration and midpoint sleep time (ie, the midpoint of bedtime and wake-up time) with depressive symptoms.ResultsThe means of sleep duration and midpoint sleep time in the participants were 6 h per night and 02:13 h, respectively. The results showed marked nonlinear associations of sleep patterns with depressive symptoms. Sleep duration shorter than 4 h per night was associated with a relatively higher level of depressive symptoms, with the highest risk (coefficient = 3.41; 95% confidence interval [CI] = 2.12, 4.70) while sleeping 2.06 h per night. The midpoint sleep time was positively associated with depressive symptom scores after 01:00 h.ConclusionsThe results showed that sleep duration and fitting sleep timing were nonlinearly associated with the risks of depressive symptoms in the general older adult population. These findings have implications for targeting nonpharmacological approaches by tackling modifiable behaviors, such as adequate sleep duration and timing, with decreased risks of depressive symptoms in the older adult population.     

Decreases in self-reported sleep duration among U.S. adolescents 2009–2015 and association with new media screen time

Study objectivesInsufficient sleep among adolescents carries significant health risks, making it important to determine social factors that change sleep duration. We sought to determine whether the self-reported sleep duration of U.S. adolescents changed between 2009 and 2015 and examine whether new media screen time (relative to other factors) might be responsible for changes in sleep.MethodsWe drew from yearly, nationally representative surveys of sleep duration and time use among adolescents conducted since 1991 (Monitoring the Future) and 2007 (Youth Risk Behavior Surveillance System of the Centers for Disease Control; total N = 369,595).ResultsCompared to 2009, adolescents in 2015 were 16%–17% more likely to report sleeping less than 7 h a night on most nights, with an increase in short sleep duration after 2011–2013. New media screen time (electronic device use, social media, and reading news online) increased over this time period and was associated with increased odds of short sleep duration, with a clear exposure–response relationship for electronic devices after 2 or more hours of use per day. Other activities associated with short sleep duration, such as homework time, working for pay, and TV watching, were relatively stable or reduced over this time period, making it unlikely that these activities caused the sudden increase in short sleep duration.ConclusionsIncreased new media screen time may be involved in the recent increases (from 35% to 41% and from 37% to 43%) in short sleep among adolescents. Public health interventions should consider electronic device use as a target of intervention to improve adolescent health.     

Gender,socioeconomic, and ethnic differences in sleep patterns in school-aged children

ObjectivesAge-related changes in sleep behavior are well described in children, yet the effect of gender, socioeconomic status (SES), and ethnicity is less clear. These factors are important when developing culturally and socially appropriate guidelines for healthy sleep. The objective of our study was to examine the effects of age, gender, SES, and ethnicity on sleep patterns in school-aged children.MethodsA cross-sectional survey was conducted through primary schools in Adelaide, South Australia. Parents reported demographic information and sleep patterns for school and non-school days for 1845 children aged 5 to 10 years.Results48% of the cohort were boys (mean age, 7.7 ± 1.7 y), 85% were Caucasian, and there was an equal distribution across defined SES bands. Sleep duration reduced with age and was shorter on non-school than school nights as a result of later bedtimes. Boys, children from low SES areas, and non-Caucasian children reported shorter sleep times than girls, children from high SES areas, and Caucasian children, respectively. Non-Caucasian children from low SES areas reported the shortest sleep opportunity.ConclusionsThe results from our study suggest that in addition to biological mechanisms, sleep behaviors are culturally and socially driven and should be considered when developing recommendations for healthy sleep in children.     

Non-REM sleep instability in children with restless sleep disorder

Study objectivesRestless sleep disorder (RSD) is a newly recognized condition characterized by motor movements involving large muscle groups with frequent repositioning or bed sheets disruption. We analyzed cyclic alternating pattern (CAP) in these children, a marker of sleep instability that might be associated with the motor episodes of RSD and may play a role in their daytime symptoms.MethodsPolysomnographic recordings from thirty-eight children who fulfilled RSD diagnostic criteria (23 boys and 15 girls), 23 children with restless legs syndrome (RLS, 18 boys and 5 girls) and 19 controls (10 boys and 9 girls) were included. For CAP analysis, a previously developed, highly precise automated system, based on a deep learning recurrent neural network, was used.ResultsAge and gender were not statistically different between groups. RSD patients showed a lower percentage of A3 CAP subtypes than controls (median 9.8 vs. 18.2, p = 0.0089), accompanied by shorter duration of the B phase of the CAP cycle (median 28.2 vs. 29.8 in controls, 30.2 in RLS, p = 0.005) and shorter CAP cycle duration than both controls and RLS subjects (median 33.8 vs. 35.0 in controls, 35.8 in RLS, p = 0.002). Finally, RSD children also showed a longer duration of CAP cycle sequences, when compared to controls (median 172.7 vs. 141.9, p = 0.0063).ConclusionsIn conclusion, our study indicates that NREM sleep EEG shows an increased instability in RSD; these findings add to the current knowledge on the mechanisms of this newly recognized sleep disorder and suggest that sleep instability might be a favoring mechanism for the emergence of the motor episodes characterizing RSD.     

Cross-cultural differences in infant and toddler sleep

BackgroundTo characterize cross-cultural sleep patterns and sleep problems in a large sample of children ages birth to 36 months in multiple predominantly-Asian (P-A) and predominantly-Caucasian (P-C) countries.MethodsParents of 29,287 infants and toddlers (predominantly-Asian countries/regions: China, Hong Kong, India, Indonesia, Korea, Japan, Malaysia, Philippines, Singapore, Taiwan, Thailand, Vietnam; predominantly-Caucasian countries: Australia, Canada, New Zealand, United Kingdom, United States) completed an internet-based expanded version of the Brief Infant Sleep Questionnaire.ResultsOverall, children from P-A countries had significantly later bedtimes, shorter total sleep times, increased parental perception of sleep problems, and were more likely to both bed-share and room-share than children from P-C countries, p < .001. Bedtimes ranged from 19:27 (New Zealand) to 22:17 (Hong Kong) and total sleep time from 11.6 (Japan) to 13.3 (New Zealand) hours, p < .0001. There were limited differences in daytime sleep. Bed-sharing with parents ranged from 5.8% in New Zealand to 83.2% in Vietnam. There was also a wide range in the percentage of parents who perceived that their child had a sleep problem (11% in Thailand to 76% in China).ConclusionsOverall, children from predominantly-Asian countries had significantly later bedtimes, shorter total sleep times, increased parental perception of sleep problems, and were more likely to room-share than children from predominantly-Caucasian countries/regions. These results indicate substantial differences in sleep patterns in young children across culturally diverse countries/regions. Further studies are needed to understand the basis for and impact of these interesting differences.     

Cross-cultural differences in the sleep of preschool children

BackgroundThe aim of our study was to characterize cross-cultural sleep patterns and sleep problems in a large sample of preschool children ages 3–6 years in multiple predominantly Asian (P-A) and predominantly Caucasian (P-C) countries/regions.MethodsParents of 2590 preschool-aged children (P-A countries/regions: China, Hong Kong, India, Japan, Korea, Malaysia, Philippines, Singapore, Thailand; P-C countries: Australia-New Zealand, Canada, United Kingdom, United States) completed an Internet-based expanded version of the Brief Child Sleep Questionnaire (BCSQ).ResultsOverall, children from P-A countries had significantly later bedtimes, shorter nighttime sleep, and increased parental perception of sleep problems compared with those from P-C countries. Bedtimes varied from as early as 7:43 pm in Australia and New Zealand to as late as 10:26 pm in India, a span of almost 3 h. There also were significant differences in daytime sleep with the majority of children in P-A countries continuing to nap, resulting in no differences in 24-h total sleep times (TST) across culture and minimal differences across specific countries. Bed sharing and room sharing are common in P-A countries, with no change across the preschool years. There also were a significant percentage of parents who perceived that their child had a sleep problem (15% in Korea to 44% in China).ConclusionsOverall, our results indicate significant cross-cultural differences in sleep patterns, sleeping arrangements, and parent-reported sleep problems in preschool-aged children. Further studies are needed to understand the underlying bases for these differences and especially for contributors to parents’ perceptions of sleep problems.     

Childhood sleep and adolescent chronic fatigue syndrome (CFS/ME): evidence of associations in a UK birth cohort

Objective/BackgroundSleep abnormalities are characteristic of chronic fatigue syndrome (CFS, also known as ‘ME’), however it is unknown whether sleep might be a causal risk factor for CFS/ME.Patients/MethodsWe analysed data from the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort. We describe sleep patterns of children aged 6 months to 11 years, who were subsequently classified as having (or not having) ‘chronic disabling fatigue’ (CDF, a proxy for CFS/ME) between the ages 13 and 18 years, and we investigated the associations of sleep duration at age nine years with CDF at age 13 years, as well as sleep duration at age 11 years with CDF at age 16 years.ResultsChildren who had CDF during adolescence had shorter night-time sleep duration from 6 months to 11 years of age, and there was strong evidence that difficulties in going to sleep were more common in children who subsequently developed CDF. The odds of CDF at age 13 years were 39% lower (odds ratio (OR) = 0.61, 95% CI = 0.43, 0.88) for each additional hour of night-time sleep at age nine years, and the odds of CDF at age 16 years were 51% lower (OR = 0.49, 95% CI = 0.34, 0.70) for each additional hour of night-time sleep at age 11 years. Mean night-time sleep duration at age nine years was 13.9 (95% CI = 3.75, 24.0) minutes shorter among children who developed CDF at age 13 years, and sleep duration at age 11 years was 18.7 (95% CI = 9.08, 28.4) minutes shorter among children who developed CDF at age 16 (compared with children who did not develop CDF at 13 and 16 years, respectively).ConclusionsChildren who develop chronic disabling fatigue in adolescence have shorter night-time sleep duration throughout early childhood, suggesting that sleep abnormalities may have a causal role in CFS/ME or that sleep abnormalities and CFS/ME are associated with a common pathophysiological cause.     

Sleep positions in children with Down syndrome and obstructive sleep apnea

ObjectivesTo assess sleep positions in children with both Down syndrome (DS) and obstructive sleep apnea (OSA) and determine if there is a preferred sleep position by severity of apnea.MethodsA single-center retrospective review of patients with both DS and OSA was performed. Caregivers reported sleep position utilized greater than 50% of observed sleep time. Accuracy of this report was confirmed through review of hypnograms from polysomnography studies.ResultsEighty-two patients met inclusion criteria. Median body mass index (BMI) was 26.6 and 56% of patients had a prior tonsillectomy and/or adenoidectomy. The mean obstructive AHI (OAHI) was 25.33 with 90.4% having severe OSA, 9.6% having moderate OSA, and no patients having mild OSA. Reported sleep positions were skewed towards lateral/decubitus (82.9%) compared to prone (11.0%) and supine (6.1%). This was consistent with hypnogram data where 71% of total sleep time in lateral/decubitus positions compared to prone (13%) and supine (6%). The median changes in sleep position per patient was 5 (IQR: 3–6). Lower BMI (p < 0.001, 95% CI: 0.32–1.13) and tonsillectomy (p < 0.001, 95% CI: 7.7–18.19) were associated with lower OAHI. Sleep position was not associated with age (p = 0.19), sex (p = 0.66), race (p = 0.10), ethnicity (p = 0.68) nor history of tonsillectomy (p = 0.34). Preferred sleep position was not correlated with OAHI (p = 0.78, r = 0.03) or OSA severity (p = 0.72, r = 0.03).ConclusionsThis study highlights the possibility that children with DS may have preferential sleep positions that cater to optimized airflow in the context of OSA although further prospective study is needed.     

Longitudinal correlates of sleep duration in young children

ObjectiveThe primary aim of this study was to longitudinally examine potential demographic and screen time correlates of nap duration, nighttime sleep duration, and total sleep duration in young children over two time points.MethodsData from the supporting Healthy physical AcTive Childcare setting (HATCH) study were analyzed. Participants were 206 toddlers (19–35 months) and preschoolers (36–60 months) in Alberta and Ontario, Canada. Child age, screen time (television, video games), and sleep duration (nap, nighttime) were measured at baseline and six-month follow-up, while other demographic variables were assessed at baseline only using the HATCH parental questionnaire. Mixed models were performed to examine the associations between potential correlates and sleep duration over time.ResultsIn the multiple regression models, significant correlates of total sleep duration (min/d) were child age (months; B = −3.03; 95%CI:-3.88,-2.19) and parental education (bachelor's degree vs. below bachelor level; B = 29.74, 95%CI:7.43,52.06). Significant correlates of nighttime sleep duration (min/d) included child age (B = −0.81; 95CI%:-1.53,-0.10), child race/ethnicity (Caucasian vs. non-Caucasian; B = 15.31; 95%CI:0.38,30.25), household income (>$150,000 vs. <$50,000; B = 32.93, 95%CI:9.80,56.06), television time (B = −0.19, 95%CI:-0.32,-0.05), video games time (B = −0.19, 95%CI: −0.38, −0.01) and total screen time (B = −0.19; 95%CI:-0.29,-0.08). Significant correlates of nap duration (min/d) were child age (B = −2.10; 95%CI:-2.68,-1.51) and race/ethnicity (Caucasian vs. non-Caucasian; B = −13.73; 95%CI:-25.78,-1.68).ConclusionYoung children who were non-Caucasian, from lower income families, who had less-educated parents, or who had more screen time tended to have shorter sleep duration. Targeting these demographic groups and screen time appears important for promoting adequate sleep duration in early childhood.     

Sleep duration and daytime sleepiness in a large sample of Brazilian high school adolescents

ObjectiveTo investigate the prevalence and main factors associated with short and long sleep duration and excessive daytime sleepiness in Brazilian adolescents.MethodsThis was a cross-sectional study of 11.525 students of both genders, aged 14–17 years, from the public high-school system. Sleep duration was assessed by self-report and <8 h of sleep per day was considered short sleep and >10 h, long sleep. Socio-demographic and behavioral factors were investigated through a purpose-built questionnaire and daytime somnolence was assessed by the Epworth sleepiness scale (ESS).ResultsThe overall prevalence of short and long sleep was 54.7% and 3.3%, respectively. Frequency of short sleep was lowest in the afternoon shift (38.2%) and highest in the morning shift (62.9%) and full-day students (70.0%). Insufficient sleep was more frequent in working (63.0%) than non-working adolescents (53.1%; p = 0.001) and among those who used their cell phone before bedtime (56.3%) compared to non-users (49.7%, p = 0.001). On average, ESS score was higher in subjects with short and long sleep (respectively, 9.7 ± 4.4 and 10.0 ± 4.5) compared to those with normal sleep duration (8.9 ± 4.2; p = 0.001).ConclusionInsufficient sleep and excessive daytime sleepiness are very common among urban high-school Brazilian adolescents. Full day and morning school shifts are associated with short sleep and daytime somnolence, suggesting later start times may have a role in reducing sleep loss in these subjects. Older age, work activity, and cell phone use before bedtime, are also risk factors for of short sleep in adolescents. Although less common, long sleep can also be associated with excessive daytime sleepiness.     

Association between change in sleep duration and posttraumatic stress symptoms in natural disaster victims: the mediating role of resilience

ObjectiveThis study investigated the association between changes in sleep duration after disaster and post-traumatic stress disorder (PTSD) symptoms and the mediating role of resilience on the association.MethodsData were collected from 2951 Korean adults who were victims of a natural disaster and did not have any mental or medical illnesses before the event. They completed a long-term survey on changes in life for disaster victims using computer-aided personal interviews. Changes in sleep duration before and one month after experiencing a disaster were assessed using a self-reported questionnaire. Resilience levels and PTSD symptoms were measured using the Brief Resilience Scale and the Impact of Event Scale – Revised, respectively, and more than 33 of the IES-R score items were defined as significant PTSD symptoms. Multivariate logistic regression was used to examine the associations between changes in sleep duration and PTSD symptoms. Additionally, mediating studies were conducted to identify the role of resilience on the association.ResultsCompared with participants without significant PTSD symptoms, those with PTSD symptoms were more likely to be older and female (group without significant PTSD symptom: mean age = 56.12 ± 18.70 years, female sex = 49.24%; group with significant PTSD symptoms: mean age = 60.88 ± 15.66 years, female sex = 59.52%). Compared with disaster victims without changes in sleep duration, those who had shorter sleep duration after disaster had a higher risk of significant PTSD symptoms (OR = 2.89, 95% Cl = 2.31–3.62, p < 0.001). In the mediating study, resilience level significantly mediated the relationship between reduced sleep duration and PTSD symptoms (direct effect: β = 0.208, 95% Cl = 0.166–0.250, p < 0.001; indirect effect: β = 0.007, 95% Cl = 0.002–0.011, p < 0.001; total effect: β = 0.215, 95% Cl = 0.173–0.257, p < 0.001).ConclusionThis study revealed that individuals with reduced sleep duration after disaster had a higher risk of PTSD symptoms, while those with increased sleep duration did not. In addition, mediating effects of resilience level on the relationship between reduced sleep duration and significant PTSD symptoms were observed.     

The short and long of adolescent sleep: the unique impact of day length

Study objectivesVariation in day length is proposed to impact sleep, yet it is unknown whether this is above the influence of behavioural factors. Day length, sleep hygiene, and parent-set bedtime were simultaneously explored, to investigate the relative importance of each on adolescents’ sleep.MethodsAn online survey was distributed in four countries at varying latitudes/longitudes (Australia, The Netherlands, Canada, Norway).ResultsOverall, 711 (242 male; age M = 15.7 ± 1.6, range = 12–19 yrs) adolescents contributed data. Hierarchical regression analyses showed good sleep hygiene was associated with earlier bedtime, shorter sleep latency, and longer sleep (β = −0.34; −0.30; 0.32, p < 0.05, respectively). Shorter day length predicted later bedtime (β = 0.11, p = 0.009), decreased sleep latency (β = −0.21, p < 0.001), and total sleep (β = −0.14, p = 0.001). Longer day length predicted earlier bedtimes (β = −0.11, p = 0.004), and longer sleep (β = 0.10, p = 0.011).ConclusionsSleep hygiene had the most clinical relevance for improving sleep, thus should be considered when implementing adolescent sleep interventions, particularly as small negative effects of shorter day length may be minimised through sleep hygiene techniques.     

Sleep quality and cognitive performance in 8-year-old children

ObjectiveThe present study examined how sleep duration and sleep quality are associated with cognitive performance in 8-year-old children using standardized neurocognitive tests.MethodsTwo hundred ninety children aged 7.4–8.8 years participated in the study. Sleep duration and quality were measured using actigraphs and the Sleep Disturbance Scale for Parents. Cognitive performance was measured using four subtests of the Wechsler Intelligence Scale for Children III, the Beery Developmental Test of Visual-Motor Integration (VMI), and the Narrative memory subtest of the Developmental Neuropsychological Assessment for Children.ResultsWhen adjusting for age, sex, and maternal education, shorter sleep duration, but not sleep quality, was associated with lower visuospatial abilities (p-values ?0.043). Sleep duration and quality were not associated with verbal abilities (p-values ?0.18). With regard to the individual test results, shorter sleep duration was associated with worse performance in Visual-Motor Integration (p = 0.028), and when excluding children with high depression scores the same was also true with Block Design (p-values ?0.047). Moreover, poor sleep efficiency was associated with worse performance in Similarities (p = 0.004).ConclusionsIn a community sample of 8-year-old children, those who slept less or had poorer sleep quality had lower test scores in cognitive tasks, particularly those pertaining to visuospatial performance, although the association was not very strong.     

Association of sleep habits with behavior problems and resilience of 6- to 7-year-old children: results from the A-CHILD study

BackgroundChildhood sleep habits are associated with mental health development; however, little is known about the impact of irregular bedtimes on the mental health of early school-aged children. The aims of this study were to examine the effect of weekday sleep habits (varying bedtimes depending on the night of the week and later than 22:00 h bedtime) on behavior problems, prosocial behavior, and resilience of children aged 6–7 years.MethodsData were taken from the Adachi Child Health Impact of Living Difficulty (A-CHILD) study, which involved the participation of 4291 caregivers of first-grade children (6–7 years old) living in Adachi City, Tokyo. Resilience (using the Children's Resilient Coping Scale), behavior problems (using the Strength and Difficulties Questionnaire), both modified to range 0–100, and sleep habits were measured via a questionnaire filled out by caregivers. Propensity-score matching was used to determine the associations between irregular and late bedtime, behavior problems, prosocial behavior, and resilience.ResultsA total of 320 (7.5%) children showed irregular bedtime on school nights and 540 (13.6%) children went to bed later than 22:00 h. Children with irregular bedtimes on weekdays showed lower resilience (β = −3.50, 95% confidence interval (CI) = −5.90 to −1.10) and higher levels of behavior problems (β = 3.29, 95% CI = 1.13–5.46), especially hyperactivity/inattention (β = 5.76, 95% CI = 2.03 to 9.49) and peer relationship problems (β = 3.79, 95% CI = 1.02–6.55). On the other hand, no association between bedtime after 22:00 h and resilience or behavior problems was found.ConclusionAmong early school-aged children, irregular bedtime on weekdays may be a risk factor for lower resilience and behavior problems.